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[PATCH v5 00/18] slab accounting for memcg [message #48518] Fri, 19 October 2012 14:20 Go to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
Note: This is basically the same as v4. During this week, I made some changes
to this series in advance based on the feedback I had in the kmemcg-stack
last submission. Although the last series was not yet extensively reviewed,
I opted for sending this out so you guys have the most up2date code to review.
So please review this one instead.

This is a followup to the previous kmem series. I divided them logically
so it gets easier for reviewers. But I believe they are ready to be merged
together (although we can do a two-pass merge if people would prefer)

Throwaway git tree found at:

git://git.kernel.org/pub/scm/linux/kernel/git/glommer/memcg. git kmemcg-slab

v5:
* code reorganization, name changes, etc.
v4:
* no more messing with the cache name after destruction: aggregated figures
are shown in /proc/slabinfo.
* memory.kmem.slabinfo file with memcg-specific cache information during its
lifespan.
* full slub attribute propagation.
* reusing the standard workqueue mechanism.
* cache-side indexing, instead of memcg-side indexing. The memcg css_id serves
as an index, and we don't need extra indexes for that.
* struct memcg_cache_params no longer bundled in struct kmem_cache: We now will
have only a pointer in the struct, allowing memory consumption when disable to
fall down ever further.

Patches need to be adjusted to cope with those changes, but other than that,
look the same - just a lot simpler.

I also put quite some effort to overcome my writing disability and get some
decent changelogs in place.

For a detailed explanation about this whole effort, please refer to my previous
post (https://lkml.org/lkml/2012/10/8/119)

Glauber Costa (18):
move slabinfo processing to slab_common.c
move print_slabinfo_header to slab_common.c
sl[au]b: process slabinfo_show in common code
slab: don't preemptively remove element from list in cache destroy
slab/slub: struct memcg_params
consider a memcg parameter in kmem_create_cache
Allocate memory for memcg caches whenever a new memcg appears
memcg: infrastructure to match an allocation to the right cache
memcg: skip memcg kmem allocations in specified code regions
sl[au]b: always get the cache from its page in kfree
sl[au]b: Allocate objects from memcg cache
memcg: destroy memcg caches
memcg/sl[au]b Track all the memcg children of a kmem_cache.
memcg/sl[au]b: shrink dead caches
Aggregate memcg cache values in slabinfo
slab: propagate tunables values
slub: slub-specific propagation changes.
Add slab-specific documentation about the kmem controller

Documentation/cgroups/memory.txt | 7 +
include/linux/memcontrol.h | 86 ++++++
include/linux/sched.h | 1 +
include/linux/slab.h | 46 +++
include/linux/slab_def.h | 3 +
include/linux/slub_def.h | 19 +-
init/Kconfig | 2 +-
mm/memcontrol.c | 613 +++++++++++++++++++++++++++++++++++++--
mm/slab.c | 188 ++++++------
mm/slab.h | 132 ++++++++-
mm/slab_common.c | 217 +++++++++++++-
mm/slub.c | 195 ++++++++-----
12 files changed, 1294 insertions(+), 215 deletions(-)

--
1.7.11.7
[PATCH v5 10/18] sl[au]b: always get the cache from its page in kfree [message #48519 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
struct page already have this information. If we start chaining
caches, this information will always be more trustworthy than
whatever is passed into the function

A parent pointer is added to the slub structure, so we can make sure
the freeing comes from either the right slab, or from its rightful
parent.

[ v3: added parent testing with VM_BUG_ON ]
[ v4: make it faster when kmemcg not in use ]

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 4 ++++
mm/slab.c | 17 ++++++++++++++++-
mm/slab.h | 13 +++++++++++++
mm/slub.c | 14 ++++++++++++--
4 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 92fc47a..f1ecb4f 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -534,6 +534,10 @@ static inline void sock_release_memcg(struct sock *sk)
{
}

+static inline bool memcg_kmem_enabled(void)
+{
+ return false;
+}
static inline bool
memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg, int order)
{
diff --git a/mm/slab.c b/mm/slab.c
index 98b3460..6f22067 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3911,9 +3911,24 @@ EXPORT_SYMBOL(__kmalloc);
* Free an object which was previously allocated from this
* cache.
*/
-void kmem_cache_free(struct kmem_cache *cachep, void *objp)
+void kmem_cache_free(struct kmem_cache *s, void *objp)
{
unsigned long flags;
+ struct kmem_cache *cachep;
+
+ /*
+ * When kmemcg is not being used, both assignments should return the
+ * same value. but we don't want to pay the assignment price in that
+ * case. If it is not compiled in, the compiler should be smart enough
+ * to not do even the assignment. In that case, slab_equal_or_root
+ * will also be a constant.
+ */
+ if (memcg_kmem_enabled()) {
+ cachep = virt_to_cache(objp);
+ VM_BUG_ON(!slab_equal_or_root(cachep, s));
+ } else
+ cachep = s;
+

local_irq_save(flags);
debug_check_no_locks_freed(objp, cachep->object_size);
diff --git a/mm/slab.h b/mm/slab.h
index c35ecce..b9b5f1f 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -108,6 +108,13 @@ static inline bool cache_match_memcg(struct kmem_cache *cachep,
return (is_root_cache(cachep) && !memcg) ||
(cachep->memcg_params->memcg == memcg);
}
+
+static inline bool slab_equal_or_root(struct kmem_cache *s,
+ struct kmem_cache *p)
+{
+ return (p == s) ||
+ (s->memcg_params && (p == s->memcg_params->root_cache));
+}
#else
static inline bool is_root_cache(struct kmem_cache *s)
{
@@ -119,5 +126,11 @@ static inline bool cache_match_memcg(struct kmem_cache *cachep,
{
return true;
}
+
+static inline bool slab_equal_or_root(struct kmem_cache *s,
+ struct kmem_cache *p)
+{
+ return true;
+}
#endif
#endif
diff --git a/mm/slub.c b/mm/slub.c
index 05aefe2..6e1a90f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2609,9 +2609,19 @@ redo:

void kmem_cache_free(struct kmem_cache *s, void *x)
{
- struct page *page;
+ struct page *page = virt_to_head_page(x);

- page = virt_to_head_page(x);
+ /*
+ * When kmemcg is not being used, both assignments should return the
+ * same value. but we don't want to pay the assignment price in that
+ * case. If it is not compiled in, the compiler should be smart enough
+ * to not do even the assignment. In that case, slab_equal_or_root
+ * will also be a constant.
+ */
+ if (memcg_kmem_enabled()) {
+ VM_BUG_ON(!slab_equal_or_root(page->slab, s));
+ s = page->slab;
+ }

if (kmem_cache_debug(s) && page->slab != s) {
pr_err("kmem_cache_free: Wrong slab cache. %s but object"
--
1.7.11.7
[PATCH v5 04/18] slab: don't preemptively remove element from list in cache destroy [message #48520 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
After the slab/slub/slob merge, we are deleting the element from the
slab_cache lists, and then if the destruction fail, we add it back
again. This behavior was present in some caches, but not in others, if
my memory doesn't fail me.

I, however, see no reason why we need to do so, since we are now locked
during the whole deletion (which wasn't necessarily true before). I
propose a simplification in which we delete it only when there is no
more going back, so we don't need to add it again.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
mm/slab_common.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 1ee1d6f..bf4b4f1 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -174,16 +174,15 @@ void kmem_cache_destroy(struct kmem_cache *s)
mutex_lock(&slab_mutex);
s->refcount--;
if (!s->refcount) {
- list_del(&s->list);
-
if (!__kmem_cache_shutdown(s)) {
if (s->flags & SLAB_DESTROY_BY_RCU)
rcu_barrier();

+ list_del(&s->list);
+
kfree(s->name);
kmem_cache_free(kmem_cache, s);
} else {
- list_add(&s->list, &slab_caches);
printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
s->name);
dump_stack();
--
1.7.11.7
[PATCH v5 09/18] memcg: skip memcg kmem allocations in specified code regions [message #48521 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
This patch creates a mechanism that skip memcg allocations during
certain pieces of our core code. It basically works in the same way
as preempt_disable()/preempt_enable(): By marking a region under
which all allocations will be accounted to the root memcg.

We need this to prevent races in early cache creation, when we
allocate data using caches that are not necessarily created already.

[ v2: wrap the whole enqueue process, INIT_WORK can alloc memory ]

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/sched.h | 1 +
mm/memcontrol.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0d907e1..9fad6c1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1581,6 +1581,7 @@ struct task_struct {
unsigned long nr_pages; /* uncharged usage */
unsigned long memsw_nr_pages; /* uncharged mem+swap usage */
} memcg_batch;
+ unsigned int memcg_kmem_skip_account;
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
atomic_t ptrace_bp_refcnt;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ac2e621..3f46daa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2950,6 +2950,41 @@ out:
kfree(s->memcg_params);
}

+/*
+ * During the creation a new cache, we need to disable our accounting mechanism
+ * altogether. This is true even if we are not creating, but rather just
+ * enqueing new caches to be created.
+ *
+ * This is because that process will trigger allocations; some visible, like
+ * explicit kmallocs to auxiliary data structures, name strings and internal
+ * cache structures; some well concealed, like INIT_WORK() that can allocate
+ * objects during debug.
+ *
+ * If any allocation happens during memcg_kmem_get_cache, we will recurse back
+ * to it. This may not be a bounded recursion: since the first cache creation
+ * failed to complete (waiting on the allocation), we'll just try to create the
+ * cache again, failing at the same point.
+ *
+ * memcg_kmem_get_cache is prepared to abort after seeing a positive count of
+ * memcg_kmem_skip_account. So we enclose anything that might allocate memory
+ * inside the following two functions.
+ */
+static void memcg_stop_kmem_account(void)
+{
+ if (!current->mm)
+ return;
+
+ current->memcg_kmem_skip_account++;
+}
+
+static void memcg_resume_kmem_account(void)
+{
+ if (!current->mm)
+ return;
+
+ current->memcg_kmem_skip_account--;
+}
+
static char *memcg_cache_name(struct mem_cgroup *memcg, struct kmem_cache *cachep)
{
char *name;
@@ -3009,7 +3044,10 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
if (new_cachep)
goto out;

+ /* Don't block progress to enqueue caches for internal infrastructure */
+ memcg_stop_kmem_account();
new_cachep = kmem_cache_dup(memcg, cachep);
+ memcg_resume_kmem_account();

if (new_cachep == NULL) {
new_cachep = cachep;
@@ -3047,8 +3085,8 @@ static void memcg_create_cache_work_func(struct work_struct *w)
* Enqueue the creation of a per-memcg kmem_cache.
* Called with rcu_read_lock.
*/
-static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
- struct kmem_cache *cachep)
+static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
+ struct kmem_cache *cachep)
{
struct create_work *cw;

@@ -3067,6 +3105,24 @@ static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
schedule_work(&cw->work);
}

+static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
+ struct kmem_cache *cachep)
+{
+ /*
+ * We need to stop accounting when we kmalloc, because if the
+ * corresponding kmalloc cache is not yet created, the first allocation
+ * in __memcg_create_cache_enqueue will recurse.
+ *
+ * However, it is better to enclose the whole function. Depending on
+ * the debugging options enabled, INIT_WORK(), for instance, can
+ * trigger an allocation. This too, will make us recurse. Because at
+ * this point we can't allow ourselves back into memcg_kmem_get_cache,
+ * the safest choice is to do it like this, wrapping the whole function.
+ */
+ memcg_stop_kmem_account();
+ __memcg_create_cache_enqueue(memcg, cachep);
+ memcg_resume_kmem_account();
+}
/*
* Return the kmem_cache we're supposed to use for a slab allocation.
* We try to use the current memcg's version of the cache.
@@ -3086,6 +3142,9 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
struct mem_cgroup *memcg;
int idx;

+ if (!current->mm || current->memcg_kmem_skip_account)
+ return cachep;
+
if (cachep->memcg_params && cachep->memcg_params->memcg)
return cachep;

--
1.7.11.7
[PATCH v5 02/18] move print_slabinfo_header to slab_common.c [message #48522 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
The header format is highly similar between slab and slub. The main
difference lays in the fact that slab may optionally have statistics
added here in case of CONFIG_SLAB_DEBUG, while the slub will stick them
somewhere else.

By making sure that information conditionally lives inside a
globally-visible CONFIG_DEBUG_SLAB switch, we can move the header
printing to a common location.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: David Rientjes <rientjes@google.com>
---
mm/slab.c | 24 ------------------------
mm/slab.h | 2 --
mm/slab_common.c | 23 +++++++++++++++++++++++
mm/slub.c | 10 ----------
4 files changed, 23 insertions(+), 36 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index e35970a..864a9e9 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4262,30 +4262,6 @@ out:
}

#ifdef CONFIG_SLABINFO
-
-void print_slabinfo_header(struct seq_file *m)
-{
- /*
- * Output format version, so at least we can change it
- * without _too_ many complaints.
- */
-#if STATS
- seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
-#else
- seq_puts(m, "slabinfo - version: 2.1\n");
-#endif
- seq_puts(m, "# name <active_objs> <num_objs> <objsize> "
- "<objperslab> <pagesperslab>");
- seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
- seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
-#if STATS
- seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
- "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
- seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
-#endif
- seq_putc(m, '\n');
-}
-
int slabinfo_show(struct seq_file *m, void *p)
{
struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
diff --git a/mm/slab.h b/mm/slab.h
index 4156d21..e9ba23f 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -74,8 +74,6 @@ int __kmem_cache_shutdown(struct kmem_cache *);

struct seq_file;
struct file;
-void print_slabinfo_header(struct seq_file *m);
-
int slabinfo_show(struct seq_file *m, void *p);

ssize_t slabinfo_write(struct file *file, const char __user *buffer,
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 11ecab4..bb4d751 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -200,6 +200,29 @@ int slab_is_available(void)
}

#ifdef CONFIG_SLABINFO
+static void print_slabinfo_header(struct seq_file *m)
+{
+ /*
+ * Output format version, so at least we can change it
+ * without _too_ many complaints.
+ */
+#ifdef CONFIG_DEBUG_SLAB
+ seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
+#else
+ seq_puts(m, "slabinfo - version: 2.1\n");
+#endif
+ seq_puts(m, "# name <active_objs> <num_objs> <objsize> "
+ "<objperslab> <pagesperslab>");
+ seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
+ seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
+#ifdef CONFIG_DEBUG_SLAB
+ seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
+ "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
+ seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
+#endif
+ seq_putc(m, '\n');
+}
+
static void *s_start(struct seq_file *m, loff_t *pos)
{
loff_t n = *pos;
diff --git a/mm/slub.c b/mm/slub.c
index 55304ed..91e1f3b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5394,16 +5394,6 @@ __initcall(slab_sysfs_init);
* The /proc/slabinfo ABI
*/
#ifdef CONFIG_SLABINFO
-void print_slabinfo_header(struct seq_file *m)
-{
- seq_puts(m, "slabinfo - version: 2.1\n");
- seq_puts(m, "# name <active_objs> <num_objs> <object_size> "
- "<objperslab> <pagesperslab>");
- seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
- seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
- seq_putc(m, '\n');
-}
-
int slabinfo_show(struct seq_file *m, void *p)
{
unsigned long nr_partials = 0;
--
1.7.11.7
[PATCH v5 11/18] sl[au]b: Allocate objects from memcg cache [message #48523 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
We are able to match a cache allocation to a particular memcg. If the
task doesn't change groups during the allocation itself - a rare event,
this will give us a good picture about who is the first group to touch a
cache page.

This patch uses the now available infrastructure by calling
memcg_kmem_get_cache() before all the cache allocations.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/slub_def.h | 15 ++++++++++-----
mm/memcontrol.c | 3 +++
mm/slab.c | 6 +++++-
mm/slub.c | 5 +++--
4 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 961e72e..ed330df 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -13,6 +13,8 @@
#include <linux/kobject.h>

#include <linux/kmemleak.h>
+#include <linux/memcontrol.h>
+#include <linux/mm.h>

enum stat_item {
ALLOC_FASTPATH, /* Allocation from cpu slab */
@@ -209,14 +211,14 @@ static __always_inline int kmalloc_index(size_t size)
* This ought to end up with a global pointer to the right cache
* in kmalloc_caches.
*/
-static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
+static __always_inline struct kmem_cache *kmalloc_slab(gfp_t flags, size_t size)
{
int index = kmalloc_index(size);

if (index == 0)
return NULL;

- return kmalloc_caches[index];
+ return memcg_kmem_get_cache(kmalloc_caches[index], flags);
}

void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
@@ -225,7 +227,10 @@ void *__kmalloc(size_t size, gfp_t flags);
static __always_inline void *
kmalloc_order(size_t size, gfp_t flags, unsigned int order)
{
- void *ret = (void *) __get_free_pages(flags | __GFP_COMP, order);
+ void *ret;
+
+ flags |= (__GFP_COMP | __GFP_KMEMCG);
+ ret = (void *) __get_free_pages(flags, order);
kmemleak_alloc(ret, size, 1, flags);
return ret;
}
@@ -274,7 +279,7 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags)
return kmalloc_large(size, flags);

if (!(flags & SLUB_DMA)) {
- struct kmem_cache *s = kmalloc_slab(size);
+ struct kmem_cache *s = kmalloc_slab(flags, size);

if (!s)
return ZERO_SIZE_PTR;
@@ -307,7 +312,7 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
if (__builtin_constant_p(size) &&
size <= SLUB_MAX_SIZE && !(flags & SLUB_DMA)) {
- struct kmem_cache *s = kmalloc_slab(size);
+ struct kmem_cache *s = kmalloc_slab(flags, size);

if (!s)
return ZERO_SIZE_PTR;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3f46daa..354cdf0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3015,6 +3015,9 @@ static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
new = kmem_cache_create_memcg(memcg, name, s->object_size, s->align,
(s->flags & ~SLAB_PANIC), s->ctor);

+ if (new)
+ new->allocflags |= __GFP_KMEMCG;
+
kfree(name);
return new;
}
diff --git a/mm/slab.c b/mm/slab.c
index 6f22067..c6cdcc0 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1949,7 +1949,7 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr)
}
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += nr_freed;
- free_pages((unsigned long)addr, cachep->gfporder);
+ free_memcg_kmem_pages((unsigned long)addr, cachep->gfporder);
}

static void kmem_rcu_free(struct rcu_head *head)
@@ -3514,6 +3514,8 @@ __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
if (slab_should_failslab(cachep, flags))
return NULL;

+ cachep = memcg_kmem_get_cache(cachep, flags);
+
cache_alloc_debugcheck_before(cachep, flags);
local_irq_save(save_flags);

@@ -3599,6 +3601,8 @@ __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller)
if (slab_should_failslab(cachep, flags))
return NULL;

+ cachep = memcg_kmem_get_cache(cachep, flags);
+
cache_alloc_debugcheck_before(cachep, flags);
local_irq_save(save_flags);
objp = __do_cache_alloc(cachep, flags);
diff --git a/mm/slub.c b/mm/slub.c
index 6e1a90f..48b7574 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1405,7 +1405,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
reset_page_mapcount(page);
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += pages;
- __free_pages(page, order);
+ __free_memcg_kmem_pages(page, order);
}

#define need_reserve_slab_rcu \
@@ -2321,6 +2321,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
if (slab_pre_alloc_hook(s, gfpflags))
return NULL;

+ s = memcg_kmem_get_cache(s, gfpflags);
redo:

/*
@@ -3478,7 +3479,7 @@ void kfree(const void *x)
if (unlikely(!PageSlab(page))) {
BUG_ON(!PageCompound(page));
kmemleak_free(x);
- __free_pages(page, compound_order(page));
+ __free_memcg_kmem_pages(page, compound_order(page));
return;
}
slab_free(page->slab, page, object, _RET_IP_);
--
1.7.11.7
[PATCH v5 17/18] slub: slub-specific propagation changes. [message #48524 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve
any tunables the parent cache already had.

This can be done by tapping into the store attribute function provided
by the allocator. We of course don't need to mess with read-only
fields. Since the attributes can have multiple types and are stored
internally by sysfs, the best strategy is to issue a ->show() in the
root cache, and then ->store() in the memcg cache.

The drawback of that, is that sysfs can allocate up to a page in
buffering for show(), that we are likely not to need, but also can't
guarantee. To avoid always allocating a page for that, we can update the
caches at store time with the maximum attribute size ever stored to the
root cache. We will then get a buffer big enough to hold it. The
corolary to this, is that if no stores happened, nothing will be
propagated.

It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/slub_def.h | 1 +
mm/slub.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index ed330df..f41acb9 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -105,6 +105,7 @@ struct kmem_cache {
#endif
#ifdef CONFIG_MEMCG_KMEM
struct memcg_cache_params *memcg_params;
+ int max_attr_size; /* for propagation, maximum size of a stored attr */
#endif

#ifdef CONFIG_NUMA
diff --git a/mm/slub.c b/mm/slub.c
index b5b970b..41c3caf 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -203,13 +203,14 @@ enum track_item { TRACK_ALLOC, TRACK_FREE };
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
static void sysfs_slab_remove(struct kmem_cache *);
-
+static void memcg_propagate_slab_attrs(struct kmem_cache *s);
#else
static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
{ return 0; }
static inline void sysfs_slab_remove(struct kmem_cache *s) { }

+static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { }
#endif

static inline void stat(const struct kmem_cache *s, enum stat_item si)
@@ -3973,6 +3974,7 @@ int __kmem_cache_create(struct kmem_cache *s, unsigned long flags)
if (err)
return err;

+ memcg_propagate_slab_attrs(s);
mutex_unlock(&slab_mutex);
err = sysfs_slab_add(s);
mutex_lock(&slab_mutex);
@@ -5198,6 +5200,7 @@ static ssize_t slab_attr_store(struct kobject *kobj,
struct slab_attribute *attribute;
struct kmem_cache *s;
int err;
+ int i __maybe_unused;

attribute = to_slab_attr(attr);
s = to_slab(kobj);
@@ -5206,10 +5209,81 @@ static ssize_t slab_attr_store(struct kobject *kobj,
return -EIO;

err = attribute->store(s, buf, len);
+#ifdef CONFIG_MEMCG_KMEM
+ if (slab_state < FULL)
+ return err;

+ if ((err < 0) || !is_root_cache(s))
+ return err;
+
+ mutex_lock(&slab_mutex);
+ if (s->max_attr_size < len)
+ s->max_attr_size = len;
+
+ for_each_memcg_cache_index(i) {
+ struct kmem_cache *c = cache_from_memcg(s, i);
+ if (c)
+ /* return value determined by the parent cache only */
+ attribute->store(c, buf, len);
+ }
+ mutex_unlock(&slab_mutex);
+#endif
return err;
}

+#ifdef CONFIG_MEMCG_KMEM
+static void memcg_propagate_slab_attrs(struct kmem_cache *s)
+{
+ int i;
+ char *buffer = NULL;
+
+ if (!is_root_cache(s))
+ return;
+
+ /*
+ * This mean this cache had no attribute written. Therefore, no point
+ * in copying default values around
+ */
+ if (!s->max_attr_size)
+ return;
+
+ for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) {
+ char mbuf[64];
+ char *buf;
+ struct slab_attribute *attr = to_slab_attr(slab_attrs[i]);
+
+ if (!attr || !attr->store || !attr->show)
+ continue;
+
+ /*
+ * It is really bad that we have to allocate here, so we will
+ * do it only as a fallback. If we actually allocate, though,
+ * we can just use the allocated buffer until the end.
+ *
+ * Most of the slub attributes will tend to be very small in
+ * size, but sysfs allows buffers up to a page, so they can
+ * theoretically happen.
+ */
+ if (buffer)
+ buf = buffer;
+ else if (s->max_attr_size < ARRAY_SIZE(mbuf))
+ buf = mbuf;
+ else {
+ buffer = (char *) get_zeroed_page(GFP_KERNEL);
+ if (WARN_ON(!buffer))
+ continue;
+ buf = buffer;
+ }
+
+ attr->show(s->memcg_params->root_cache, buf);
+ attr->store(s, buf, strlen(buf));
+ }
+
+ if (buffer)
+ free_page((unsigned long)buffer);
+}
+#endif
+
static const struct sysfs_ops slab_sysfs_ops = {
.show = slab_attr_show,
.store = slab_attr_store,
--
1.7.11.7
[PATCH v5 06/18] consider a memcg parameter in kmem_create_cache [message #48525 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
Allow a memcg parameter to be passed during cache creation. When the slub
allocator is being used, it will only merge caches that belong to the same
memcg.

Default function is created as a wrapper, passing NULL to the memcg version. We
only merge caches that belong to the same memcg.

A helper is provided, memcg_css_id: because slub needs a unique cache name for
sysfs. Since this is visible, but not the canonical location for slab data, the
cache name is not used, the css_id should suffice.

[ v2: moved to idr/ida instead of redoing the indexes ]
[ v3: moved call to ida_init away from cgroup creation to fix a bug ]
[ v4: no longer using the index mechanism ]

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 22 +++++++++++++++++++++
include/linux/slab.h | 12 +++++++++++-
mm/memcontrol.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++
mm/slab.h | 23 ++++++++++++++++++----
mm/slab_common.c | 40 +++++++++++++++++++++++++++----------
mm/slub.c | 16 +++++++++++----
6 files changed, 143 insertions(+), 19 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index fd4ff56..4f89a45 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -28,6 +28,7 @@ struct mem_cgroup;
struct page_cgroup;
struct page;
struct mm_struct;
+struct kmem_cache;

/* Stats that can be updated by kernel. */
enum mem_cgroup_page_stat_item {
@@ -414,6 +415,11 @@ void __memcg_kmem_commit_charge(struct page *page,
struct mem_cgroup *memcg, int order);
void __memcg_kmem_uncharge_pages(struct page *page, int order);

+int memcg_css_id(struct mem_cgroup *memcg);
+int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s);
+void memcg_release_cache(struct kmem_cache *cachep);
+void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep);
+
/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
* @gfp: the gfp allocation flags.
@@ -505,6 +511,22 @@ static inline void
memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, int order)
{
}
+
+static inline int memcg_register_cache(struct mem_cgroup *memcg,
+ struct kmem_cache *s)
+{
+ return 0;
+}
+
+static inline void memcg_release_cache(struct kmem_cache *cachep)
+{
+}
+
+static inline void memcg_cache_list_add(struct mem_cgroup *memcg,
+ struct kmem_cache *s)
+{
+ BUG();
+}
#endif /* CONFIG_MEMCG_KMEM */
#endif /* _LINUX_MEMCONTROL_H */

diff --git a/include/linux/slab.h b/include/linux/slab.h
index e4ea48a..b22a158 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -116,6 +116,7 @@ struct kmem_cache {
};
#endif

+struct mem_cgroup;
/*
* struct kmem_cache related prototypes
*/
@@ -125,6 +126,9 @@ int slab_is_available(void);
struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
unsigned long,
void (*)(void *));
+struct kmem_cache *
+kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
+ unsigned long, void (*)(void *));
void kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
@@ -193,15 +197,21 @@ unsigned int kmem_cache_size(struct kmem_cache *);
* Child caches will hold extra metadata needed for its operation. Fields are:
*
* @memcg: pointer to the memcg this cache belongs to
+ * @root_cache: pointer to the global, root cache, this cache was derived from
*/
struct memcg_cache_params {
bool is_root_cache;
union {
struct kmem_cache *memcg_caches[0];
- struct mem_cgroup *memcg;
+ struct {
+ struct mem_cgroup *memcg;
+ struct kmem_cache *root_cache;
+ };
};
};

+int memcg_update_all_caches(int num_memcgs);
+
/*
* Common kmalloc functions provided by all allocators
*/
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6a1e096..59f6d54 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -339,6 +339,12 @@ struct mem_cgroup {
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
struct tcp_memcontrol tcp_mem;
#endif
+#if defined(CONFIG_MEMCG_KMEM)
+ /* analogous to slab_common's slab_caches list. per-memcg */
+ struct list_head memcg_slab_caches;
+ /* Not a spinlock, we can take a lot of time walking the list */
+ struct mutex slab_caches_mutex;
+#endif
};

/* internal only representation about the status of kmem accounting. */
@@ -2755,6 +2761,49 @@ static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
mem_cgroup_put(memcg);
}

+void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep)
+{
+ mutex_lock(&memcg->slab_caches_mutex);
+ list_add(&cachep->list, &memcg->memcg_slab_caches);
+ mutex_unlock(&memcg->slab_caches_mutex);
+}
+
+/*
+ * helper for acessing a memcg's index. It will be used as an index in the
+ * child cache array in kmem_cache, and also to derive its name.
+ *
+ * According to kernel/cgroup.c, needs to be rcu protected.
+ */
+int memcg_css_id(struct mem_cgroup *memcg)
+{
+ int id;
+ rcu_read_lock();
+ id = css_id(&memcg->css);
+ rcu_read_unlock();
+ return id;
+}
+
+int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
+{
+ size_t size = sizeof(struct memcg_cache_params);
+
+ if (!memcg_kmem_enabled())
+ return 0;
+
+ s->memcg_params = kzalloc(size, GFP_KERNEL);
+ if (!s->memcg_params)
+ return -ENOMEM;
+
+ if (memcg)
+ s->memcg_params->memcg = memcg;
+ return 0;
+}
+
+void memcg_release_cache(struct kmem_cache *s)
+{
+ kfree(s->memcg_params);
+}
+
/*
* We need to verify if the allocation against current->mm->owner's memcg is
* possible for the given order. But the page is not allocated yet, so we'll
diff --git a/mm/slab.h b/mm/slab.h
index 5ee1851..c35ecce 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -35,12 +35,15 @@ extern struct kmem_cache *kmem_cache;
/* Functions provided by the slab allocators */
extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);

+struct mem_cgroup;
#ifdef CONFIG_SLUB
-struct kmem_cache *__kmem_cache_alias(const char *name, size_t size,
- size_t align, unsigned long flags, void (*ctor)(void *));
+struct kmem_cache *
+__kmem_cache_alias(struct mem_cgroup *memcg, const char *name, size_t size,
+ size_t align, unsigned long flags, void (*ctor)(void *));
#else
-static inline struct kmem_cache *__kmem_cache_alias(const char *name, size_t size,
- size_t align, unsigned long flags, void (*ctor)(void *))
+static inline struct kmem_cache *
+__kmem_cache_alias(struct mem_cgroup *memcg, const char *name, size_t size,
+ size_t align, unsigned long flags, void (*ctor)(void *))
{ return NULL; }
#endif

@@ -98,11 +101,23 @@ static inline bool is_root_cache(struct kmem_cache *s)
{
return !s->memcg_params || s->memcg_params->is_root_cache;
}
+
+static inline bool cache_match_memcg(struct kmem_cache *cachep,
+ struct mem_cgroup *memcg)
+{
+ return (is_root_cache(cachep) && !memcg) ||
+ (cachep->memcg_params->memcg == memcg);
+}
#else
static inline bool is_root_cache(struct kmem_cache *s)
{
return true;
}

+static inline bool cache_match_memcg(struct kmem_cache *cachep,
+ struct mem_cgroup *memcg)
+{
+ return true;
+}
#endif
#endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index bf4b4f1..f97f7b8 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -18,6 +18,7 @@
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
+#include <linux/memcontrol.h>

#include "slab.h"

@@ -27,7 +28,8 @@ DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;

#ifdef CONFIG_DEBUG_VM
-static int kmem_cache_sanity_check(const char *name, size_t size)
+static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
+ size_t size)
{
struct kmem_cache *s = NULL;

@@ -53,7 +55,7 @@ static int kmem_cache_sanity_check(const char *name, size_t size)
continue;
}

- if (!strcmp(s->name, name)) {
+ if (cache_match_memcg(s, memcg) && !strcmp(s->name, name)) {
pr_err("%s (%s): Cache name already exists.\n",
__func__, name);
dump_stack();
@@ -66,7 +68,8 @@ static int kmem_cache_sanity_check(const char *name, size_t size)
return 0;
}
#else
-static inline int kmem_cache_sanity_check(const char *name, size_t size)
+static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg,
+ const char *name, size_t size)
{
return 0;
}
@@ -97,8 +100,9 @@ static inline int kmem_cache_sanity_check(const char *name, size_t size)
* as davem.
*/

-struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
- unsigned long flags, void (*ctor)(void *))
+struct kmem_cache *
+kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
+ size_t align, unsigned long flags, void (*ctor)(void *))
{
struct kmem_cache *s = NULL;
int err = 0;
@@ -106,7 +110,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
get_online_cpus();
mutex_lock(&slab_mutex);

- if (!kmem_cache_sanity_check(name, size) == 0)
+ if (!kmem_cache_sanity_check(memcg, name, size) == 0)
goto out_locked;

/*
@@ -117,7 +121,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
*/
flags &= CACHE_CREATE_MASK;

- s = __kmem_cache_alias(name, size, align, flags, ctor);
+ s = __kmem_cache_alias(memcg, name, size, align, flags, ctor);
if (s)
...

[PATCH v5 05/18] slab/slub: struct memcg_params [message #48526 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
For the kmem slab controller, we need to record some extra
information in the kmem_cache structure.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Suleiman Souhlal <suleiman@google.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/slab.h | 25 +++++++++++++++++++++++++
include/linux/slab_def.h | 3 +++
include/linux/slub_def.h | 3 +++
mm/slab.h | 13 +++++++++++++
4 files changed, 44 insertions(+)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 0dd2dfa..e4ea48a 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -177,6 +177,31 @@ unsigned int kmem_cache_size(struct kmem_cache *);
#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
#endif

+#include <linux/workqueue.h>
+/*
+ * This is the main placeholder for memcg-related information in kmem caches.
+ * struct kmem_cache will hold a pointer to it, so the memory cost while
+ * disabled is 1 pointer. The runtime cost while enabled, gets bigger than it
+ * would otherwise be if that would be bundled in kmem_cache: we'll need an
+ * extra pointer chase. But the trade off clearly lays in favor of not
+ * penalizing non-users.
+ *
+ * Both the root cache and the child caches will have it. For the root cache,
+ * this will hold a dynamically allocated array large enough to hold
+ * information about the currently limited memcgs in the system.
+ *
+ * Child caches will hold extra metadata needed for its operation. Fields are:
+ *
+ * @memcg: pointer to the memcg this cache belongs to
+ */
+struct memcg_cache_params {
+ bool is_root_cache;
+ union {
+ struct kmem_cache *memcg_caches[0];
+ struct mem_cgroup *memcg;
+ };
+};
+
/*
* Common kmalloc functions provided by all allocators
*/
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index 36d7031..665afa4 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -81,6 +81,9 @@ struct kmem_cache {
*/
int obj_offset;
#endif /* CONFIG_DEBUG_SLAB */
+#ifdef CONFIG_MEMCG_KMEM
+ struct memcg_cache_params *memcg_params;
+#endif

/* 6) per-cpu/per-node data, touched during every alloc/free */
/*
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index df448ad..961e72e 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -101,6 +101,9 @@ struct kmem_cache {
#ifdef CONFIG_SYSFS
struct kobject kobj; /* For sysfs */
#endif
+#ifdef CONFIG_MEMCG_KMEM
+ struct memcg_cache_params *memcg_params;
+#endif

#ifdef CONFIG_NUMA
/*
diff --git a/mm/slab.h b/mm/slab.h
index 66a62d3..5ee1851 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -92,4 +92,17 @@ void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
ssize_t slabinfo_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos);
+
+#ifdef CONFIG_MEMCG_KMEM
+static inline bool is_root_cache(struct kmem_cache *s)
+{
+ return !s->memcg_params || s->memcg_params->is_root_cache;
+}
+#else
+static inline bool is_root_cache(struct kmem_cache *s)
+{
+ return true;
+}
+
+#endif
#endif
--
1.7.11.7
[PATCH v5 18/18] Add slab-specific documentation about the kmem controller [message #48527 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
Documentation/cgroups/memory.txt | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 206853b..9d9938d 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -301,6 +301,13 @@ to trigger slab reclaim when those limits are reached.
kernel memory, we prevent new processes from being created when the kernel
memory usage is too high.

+* slab pages: pages allocated by the SLAB or SLUB allocator are tracked. A copy
+of each kmem_cache is created everytime the cache is touched by the first time
+from inside the memcg. The creation is done lazily, so some objects can still be
+skipped while the cache is being created. All objects in a slab page should
+belong to the same memcg. This only fails to hold when a task is migrated to a
+different memcg during the page allocation by the cache.
+
* sockets memory pressure: some sockets protocols have memory pressure
thresholds. The Memory Controller allows them to be controlled individually
per cgroup, instead of globally.
--
1.7.11.7
[PATCH v5 13/18] memcg/sl[au]b Track all the memcg children of a kmem_cache. [message #48528 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
This enables us to remove all the children of a kmem_cache being
destroyed, if for example the kernel module it's being used in
gets unloaded. Otherwise, the children will still point to the
destroyed parent.

Signed-off-by: Suleiman Souhlal <suleiman@google.com>
Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 5 +++++
mm/memcontrol.c | 32 ++++++++++++++++++++++++++++++--
mm/slab_common.c | 3 +++
3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 9152d49..5c1d234 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -427,6 +427,7 @@ struct kmem_cache *
__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);

void mem_cgroup_destroy_cache(struct kmem_cache *cachep);
+void kmem_cache_destroy_memcg_children(struct kmem_cache *s);

/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
@@ -576,6 +577,10 @@ memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
{
return cachep;
}
+
+static inline void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
+{
+}
#endif /* CONFIG_MEMCG_KMEM */
#endif /* _LINUX_MEMCONTROL_H */

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0359b3a..f5089b3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2715,6 +2715,8 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
memcg_check_events(memcg, page);
}

+static DEFINE_MUTEX(set_limit_mutex);
+
#ifdef CONFIG_MEMCG_KMEM
static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
{
@@ -3095,6 +3097,34 @@ out:
return new_cachep;
}

+void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
+{
+ struct kmem_cache *c;
+ int i;
+
+ if (!s->memcg_params)
+ return;
+ if (!s->memcg_params->is_root_cache)
+ return;
+
+ /*
+ * If the cache is being destroyed, we trust that there is no one else
+ * requesting objects from it. Even if there are, the sanity checks in
+ * kmem_cache_destroy should caught this ill-case.
+ *
+ * Still, we don't want anyone else freeing memcg_caches under our
+ * noses, which can happen if a new memcg comes to life. As usual,
+ * we'll take the set_limit_mutex to protect ourselves against this.
+ */
+ mutex_lock(&set_limit_mutex);
+ for (i = 0; i < memcg_limited_groups_array_size; i++) {
+ c = s->memcg_params->memcg_caches[i];
+ if (c)
+ kmem_cache_destroy(c);
+ }
+ mutex_unlock(&set_limit_mutex);
+}
+
struct create_work {
struct mem_cgroup *memcg;
struct kmem_cache *cachep;
@@ -4192,8 +4222,6 @@ void mem_cgroup_print_bad_page(struct page *page)
}
#endif

-static DEFINE_MUTEX(set_limit_mutex);
-
static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
unsigned long long val)
{
diff --git a/mm/slab_common.c b/mm/slab_common.c
index fcf59d7..c02faf5 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -214,6 +214,9 @@ EXPORT_SYMBOL(kmem_cache_create);

void kmem_cache_destroy(struct kmem_cache *s)
{
+ /* Destroy all the children caches if we aren't a memcg cache */
+ kmem_cache_destroy_memcg_children(s);
+
get_online_cpus();
mutex_lock(&slab_mutex);
s->refcount--;
--
1.7.11.7
[PATCH v5 14/18] memcg/sl[au]b: shrink dead caches [message #48529 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
In the slub allocator, when the last object of a page goes away, we
don't necessarily free it - there is not necessarily a test for empty
page in any slab_free path.

This means that when we destroy a memcg cache that happened to be empty,
those caches may take a lot of time to go away: removing the memcg
reference won't destroy them - because there are pending references, and
the empty pages will stay there, until a shrinker is called upon for any
reason.

This patch marks all memcg caches as dead. kmem_cache_shrink is called
for the ones who are not yet dead - this will force internal cache
reorganization, and then all references to empty pages will be removed.

An unlikely branch is used to make sure this case does not affect
performance in the usual slab_free path.

The slab allocator has a time based reaper that would eventually get rid
of the objects, but we can also call it explicitly, since dead caches
are not a likely event.

[ v2: also call verify_dead for the slab ]
[ v3: use delayed_work to avoid calling verify_dead at every free]

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/slab.h | 2 +-
mm/memcontrol.c | 47 +++++++++++++++++++++++++++++++++++++++++------
2 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index bb698dc..4a3a749 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -212,7 +212,7 @@ struct memcg_cache_params {
struct kmem_cache *root_cache;
bool dead;
atomic_t nr_pages;
- struct work_struct destroy;
+ struct delayed_work destroy;
};
};
};
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f5089b3..c7732fa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2956,14 +2956,37 @@ static void kmem_cache_destroy_work_func(struct work_struct *w)
{
struct kmem_cache *cachep;
struct memcg_cache_params *p;
+ struct delayed_work *dw = to_delayed_work(w);

- p = container_of(w, struct memcg_cache_params, destroy);
+ p = container_of(dw, struct memcg_cache_params, destroy);

VM_BUG_ON(p->is_root_cache);
cachep = p->root_cache;
cachep = cachep->memcg_params->memcg_caches[memcg_css_id(p->memcg)];

- if (!atomic_read(&cachep->memcg_params->nr_pages))
+ /*
+ * If we get down to 0 after shrink, we could delete right away.
+ * However, memcg_release_pages() already puts us back in the workqueue
+ * in that case. If we proceed deleting, we'll get a dangling
+ * reference, and removing the object from the workqueue in that case
+ * is unnecessary complication. We are not a fast path.
+ *
+ * Note that this case is fundamentally different from racing with
+ * shrink_slab(): if memcg_cgroup_destroy_cache() is called in
+ * kmem_cache_shrink, not only we would be reinserting a dead cache
+ * into the queue, but doing so from inside the worker racing to
+ * destroy it.
+ *
+ * So if we aren't down to zero, we'll just schedule a worker and try
+ * again
+ */
+ if (atomic_read(&cachep->memcg_params->nr_pages) != 0) {
+ kmem_cache_shrink(cachep);
+ if (atomic_read(&cachep->memcg_params->nr_pages) == 0)
+ return;
+ /* Once per minute should be good enough. */
+ schedule_delayed_work(&cachep->memcg_params->destroy, 60 * HZ);
+ } else
kmem_cache_destroy(cachep);
}

@@ -2973,10 +2996,22 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
return;

/*
+ * We can get to a memory-pressure situation while the delayed work is
+ * still pending to run. The vmscan shrinkers can then release all
+ * cache memory and get us to destruction. If this is the case, we'll
+ * be executed twice, which is a bug (the second time will execute over
+ * bogus data).
+ *
+ * Since we can't possibly know who got us here, just refrain from
+ * running if there is already work pending
+ */
+ if (delayed_work_pending(&cachep->memcg_params->destroy))
+ return;
+ /*
* We have to defer the actual destroying to a workqueue, because
* we might currently be in a context that cannot sleep.
*/
- schedule_work(&cachep->memcg_params->destroy);
+ schedule_delayed_work(&cachep->memcg_params->destroy, 0);
}

/*
@@ -3142,9 +3177,9 @@ static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
list_for_each_entry(cachep, &memcg->memcg_slab_caches, list) {

cachep->memcg_params->dead = true;
- INIT_WORK(&cachep->memcg_params->destroy,
- kmem_cache_destroy_work_func);
- schedule_work(&cachep->memcg_params->destroy);
+ INIT_DELAYED_WORK(&cachep->memcg_params->destroy,
+ kmem_cache_destroy_work_func);
+ schedule_delayed_work(&cachep->memcg_params->destroy, 0);
}
mutex_unlock(&memcg->slab_caches_mutex);
}
--
1.7.11.7
[PATCH v5 03/18] sl[au]b: process slabinfo_show in common code [message #48530 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
With all the infrastructure in place, we can now have slabinfo_show
done from slab_common.c. A cache-specific function is called to grab
information about the cache itself, since that is still heavily
dependent on the implementation. But with the values produced by it, all
the printing and handling is done from common code.

[ v2: moved objects_per_slab and cache_order to slabinfo ]

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: David Rientjes <rientjes@google.com>
---
mm/slab.c | 26 +++++++++++++++-----------
mm/slab.h | 16 +++++++++++++++-
mm/slab_common.c | 18 +++++++++++++++++-
mm/slub.c | 24 ++++++++++--------------
4 files changed, 57 insertions(+), 27 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 864a9e9..98b3460 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4262,9 +4262,8 @@ out:
}

#ifdef CONFIG_SLABINFO
-int slabinfo_show(struct seq_file *m, void *p)
+void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)
{
- struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
struct slab *slabp;
unsigned long active_objs;
unsigned long num_objs;
@@ -4319,13 +4318,20 @@ int slabinfo_show(struct seq_file *m, void *p)
if (error)
printk(KERN_ERR "slab: cache %s error: %s\n", name, error);

- seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
- name, active_objs, num_objs, cachep->size,
- cachep->num, (1 << cachep->gfporder));
- seq_printf(m, " : tunables %4u %4u %4u",
- cachep->limit, cachep->batchcount, cachep->shared);
- seq_printf(m, " : slabdata %6lu %6lu %6lu",
- active_slabs, num_slabs, shared_avail);
+ sinfo->active_objs = active_objs;
+ sinfo->num_objs = num_objs;
+ sinfo->active_slabs = active_slabs;
+ sinfo->num_slabs = num_slabs;
+ sinfo->shared_avail = shared_avail;
+ sinfo->limit = cachep->limit;
+ sinfo->batchcount = cachep->batchcount;
+ sinfo->shared = cachep->shared;
+ sinfo->objects_per_slab = cachep->num;
+ sinfo->cache_order = cachep->gfporder;
+}
+
+void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *cachep)
+{
#if STATS
{ /* list3 stats */
unsigned long high = cachep->high_mark;
@@ -4355,8 +4361,6 @@ int slabinfo_show(struct seq_file *m, void *p)
allochit, allocmiss, freehit, freemiss);
}
#endif
- seq_putc(m, '\n');
- return 0;
}

#define MAX_SLABINFO_WRITE 128
diff --git a/mm/slab.h b/mm/slab.h
index e9ba23f..66a62d3 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -74,8 +74,22 @@ int __kmem_cache_shutdown(struct kmem_cache *);

struct seq_file;
struct file;
-int slabinfo_show(struct seq_file *m, void *p);

+struct slabinfo {
+ unsigned long active_objs;
+ unsigned long num_objs;
+ unsigned long active_slabs;
+ unsigned long num_slabs;
+ unsigned long shared_avail;
+ unsigned int limit;
+ unsigned int batchcount;
+ unsigned int shared;
+ unsigned int objects_per_slab;
+ unsigned int cache_order;
+};
+
+void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
+void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
ssize_t slabinfo_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos);
#endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index bb4d751..1ee1d6f 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -246,7 +246,23 @@ static void s_stop(struct seq_file *m, void *p)

static int s_show(struct seq_file *m, void *p)
{
- return slabinfo_show(m, p);
+ struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
+ struct slabinfo sinfo;
+
+ memset(&sinfo, 0, sizeof(sinfo));
+ get_slabinfo(s, &sinfo);
+
+ seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
+ s->name, sinfo.active_objs, sinfo.num_objs, s->size,
+ sinfo.objects_per_slab, (1 << sinfo.cache_order));
+
+ seq_printf(m, " : tunables %4u %4u %4u",
+ sinfo.limit, sinfo.batchcount, sinfo.shared);
+ seq_printf(m, " : slabdata %6lu %6lu %6lu",
+ sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
+ slabinfo_show_stats(m, s);
+ seq_putc(m, '\n');
+ return 0;
}

/*
diff --git a/mm/slub.c b/mm/slub.c
index 91e1f3b..a34548e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5394,18 +5394,14 @@ __initcall(slab_sysfs_init);
* The /proc/slabinfo ABI
*/
#ifdef CONFIG_SLABINFO
-int slabinfo_show(struct seq_file *m, void *p)
+void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo)
{
unsigned long nr_partials = 0;
unsigned long nr_slabs = 0;
- unsigned long nr_inuse = 0;
unsigned long nr_objs = 0;
unsigned long nr_free = 0;
- struct kmem_cache *s;
int node;

- s = list_entry(p, struct kmem_cache, list);
-
for_each_online_node(node) {
struct kmem_cache_node *n = get_node(s, node);

@@ -5418,16 +5414,16 @@ int slabinfo_show(struct seq_file *m, void *p)
nr_free += count_partial(n, count_free);
}

- nr_inuse = nr_objs - nr_free;
+ sinfo->active_objs = nr_objs - nr_free;
+ sinfo->num_objs = nr_objs;
+ sinfo->active_slabs = nr_slabs;
+ sinfo->num_slabs = nr_slabs;
+ sinfo->objects_per_slab = oo_objects(s->oo);
+ sinfo->cache_order = oo_order(s->oo);
+}

- seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", s->name, nr_inuse,
- nr_objs, s->size, oo_objects(s->oo),
- (1 << oo_order(s->oo)));
- seq_printf(m, " : tunables %4u %4u %4u", 0, 0, 0);
- seq_printf(m, " : slabdata %6lu %6lu %6lu", nr_slabs, nr_slabs,
- 0UL);
- seq_putc(m, '\n');
- return 0;
+void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s)
+{
}

ssize_t slabinfo_write(struct file *file, const char __user *buffer,
--
1.7.11.7
[PATCH v5 01/18] move slabinfo processing to slab_common.c [message #48531 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
This patch moves all the common machinery to slabinfo processing
to slab_common.c. We can do better by noticing that the output is
heavily common, and having the allocators to just provide finished
information about this. But after this first step, this can be done
easier.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: David Rientjes <rientjes@google.com>
---
mm/slab.c | 72 ++++++++++----------------------------------------------
mm/slab.h | 8 +++++++
mm/slab_common.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
mm/slub.c | 51 ++++-----------------------------------
4 files changed, 96 insertions(+), 105 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index eafef58..e35970a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4263,7 +4263,7 @@ out:

#ifdef CONFIG_SLABINFO

-static void print_slabinfo_header(struct seq_file *m)
+void print_slabinfo_header(struct seq_file *m)
{
/*
* Output format version, so at least we can change it
@@ -4286,28 +4286,7 @@ static void print_slabinfo_header(struct seq_file *m)
seq_putc(m, '\n');
}

-static void *s_start(struct seq_file *m, loff_t *pos)
-{
- loff_t n = *pos;
-
- mutex_lock(&slab_mutex);
- if (!n)
- print_slabinfo_header(m);
-
- return seq_list_start(&slab_caches, *pos);
-}
-
-static void *s_next(struct seq_file *m, void *p, loff_t *pos)
-{
- return seq_list_next(p, &slab_caches, pos);
-}
-
-static void s_stop(struct seq_file *m, void *p)
-{
- mutex_unlock(&slab_mutex);
-}
-
-static int s_show(struct seq_file *m, void *p)
+int slabinfo_show(struct seq_file *m, void *p)
{
struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
struct slab *slabp;
@@ -4404,27 +4383,6 @@ static int s_show(struct seq_file *m, void *p)
return 0;
}

-/*
- * slabinfo_op - iterator that generates /proc/slabinfo
- *
- * Output layout:
- * cache-name
- * num-active-objs
- * total-objs
- * object size
- * num-active-slabs
- * total-slabs
- * num-pages-per-slab
- * + further values on SMP and with statistics enabled
- */
-
-static const struct seq_operations slabinfo_op = {
- .start = s_start,
- .next = s_next,
- .stop = s_stop,
- .show = s_show,
-};
-
#define MAX_SLABINFO_WRITE 128
/**
* slabinfo_write - Tuning for the slab allocator
@@ -4433,7 +4391,7 @@ static const struct seq_operations slabinfo_op = {
* @count: data length
* @ppos: unused
*/
-static ssize_t slabinfo_write(struct file *file, const char __user *buffer,
+ssize_t slabinfo_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
char kbuf[MAX_SLABINFO_WRITE + 1], *tmp;
@@ -4476,19 +4434,6 @@ static ssize_t slabinfo_write(struct file *file, const char __user *buffer,
return res;
}

-static int slabinfo_open(struct inode *inode, struct file *file)
-{
- return seq_open(file, &slabinfo_op);
-}
-
-static const struct file_operations proc_slabinfo_operations = {
- .open = slabinfo_open,
- .read = seq_read,
- .write = slabinfo_write,
- .llseek = seq_lseek,
- .release = seq_release,
-};
-
#ifdef CONFIG_DEBUG_SLAB_LEAK

static void *leaks_start(struct seq_file *m, loff_t *pos)
@@ -4617,6 +4562,16 @@ static int leaks_show(struct seq_file *m, void *p)
return 0;
}

+static void *s_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ return seq_list_next(p, &slab_caches, pos);
+}
+
+static void s_stop(struct seq_file *m, void *p)
+{
+ mutex_unlock(&slab_mutex);
+}
+
static const struct seq_operations slabstats_op = {
.start = leaks_start,
.next = s_next,
@@ -4651,7 +4606,6 @@ static const struct file_operations proc_slabstats_operations = {

static int __init slab_proc_init(void)
{
- proc_create("slabinfo",S_IWUSR|S_IRUSR,NULL,&proc_slabinfo_operations);
#ifdef CONFIG_DEBUG_SLAB_LEAK
proc_create("slab_allocators", 0, NULL, &proc_slabstats_operations);
#endif
diff --git a/mm/slab.h b/mm/slab.h
index 35b60b7..4156d21 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -72,4 +72,12 @@ static inline struct kmem_cache *__kmem_cache_alias(const char *name, size_t siz

int __kmem_cache_shutdown(struct kmem_cache *);

+struct seq_file;
+struct file;
+void print_slabinfo_header(struct seq_file *m);
+
+int slabinfo_show(struct seq_file *m, void *p);
+
+ssize_t slabinfo_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos);
#endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 0e2b8e3..11ecab4 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -13,6 +13,8 @@
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
@@ -196,3 +198,71 @@ int slab_is_available(void)
{
return slab_state >= UP;
}
+
+#ifdef CONFIG_SLABINFO
+static void *s_start(struct seq_file *m, loff_t *pos)
+{
+ loff_t n = *pos;
+
+ mutex_lock(&slab_mutex);
+ if (!n)
+ print_slabinfo_header(m);
+
+ return seq_list_start(&slab_caches, *pos);
+}
+
+static void *s_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ return seq_list_next(p, &slab_caches, pos);
+}
+
+static void s_stop(struct seq_file *m, void *p)
+{
+ mutex_unlock(&slab_mutex);
+}
+
+static int s_show(struct seq_file *m, void *p)
+{
+ return slabinfo_show(m, p);
+}
+
+/*
+ * slabinfo_op - iterator that generates /proc/slabinfo
+ *
+ * Output layout:
+ * cache-name
+ * num-active-objs
+ * total-objs
+ * object size
+ * num-active-slabs
+ * total-slabs
+ * num-pages-per-slab
+ * + further values on SMP and with statistics enabled
+ */
+static const struct seq_operations slabinfo_op = {
+ .start = s_start,
+ .next = s_next,
+ .stop = s_stop,
+ .show = s_show,
+};
+
+static int slabinfo_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &slabinfo_op);
+}
+
+static const struct file_operations proc_slabinfo_operations = {
+ .open = slabinfo_open,
+ .read = seq_read,
+ .write = slabinfo_write,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+static int __init slab_proc_init(void)
+{
+ proc_create("slabinfo", S_IRUSR, NULL, &proc_slabinfo_operations);
+ return 0;
+}
+module_init(slab_proc_init);
+#endif /* CONFIG_SLABINFO */
diff --git a/mm/slub.c b/mm/slub.c
index f50c5b2..55304ed 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5394,7 +5394,7 @@ __initcall(slab_sysfs_init);
* The /proc/slabinfo ABI
*/
#ifdef CONFIG_SLABINFO
-static void print_slabinfo_header(struct seq_file *m)
+void print_slabinfo_header(struct seq_file *m)
{
seq_puts(m, "slabinfo - version: 2.1\n");
seq_puts(m, "# name <active_objs> <num_objs> <object_size> "
@@ -5404,28 +5404,7 @@ static void print_slabinfo_header(struct seq_file *m)
seq_putc(m, '\n');
}

-static void *s_start(struct seq_file *m, loff_t *pos)
-{
- loff_t n = *pos;
-
- mutex_lock(&slab_mutex);
- if (!n)
- print_slabinfo_header(m);
-
- return seq_list_start(&slab_caches, *pos);
-}
-
-static void *s_next(struct seq_file *m, void *p, loff_t *pos)
-{
- return seq_list_next(p, &slab_caches, pos);
-}
-
-static void s_stop(struct seq_file *m, void *p)
-{
- mutex_unlock(&slab_mutex);
-}
-
-static int s_show(struct seq_file *m, void *p)
+int slabinfo_show(struct seq_file *m, void *p)
{
unsigned long nr_partials = 0;
unsigned long nr_slabs = 0;
@@ -5461,29 +5440,9 @@ static int s_show(struct seq_file *m, void *p)
return 0;
}

-static const struct seq_operations slabinfo_op = {
- .start = s_start,
- .next = s_next,
- .stop = s_stop,
- .show = s_show,
-};
-
-static int slabinfo_open(struct inode *inode, struct file *file)
-{
- return seq_open(file, &slabinfo_op);
-}
-
-static const struct file_operations proc_slabinfo_operations = {
- .open = slabinfo_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = seq_release,
-};
-
-static int __init slab_proc_init(void)
+ssize_t slabinfo_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
{
- proc_create("slabinfo", S_IRUSR, NULL, &proc_slabinfo_operations);
- return 0;
+ return -EIO;
}
-module_init(slab_proc_init);
#endif /* CONFIG_SLABINFO */
--
1.7.11.7
...

[PATCH v5 15/18] Aggregate memcg cache values in slabinfo [message #48532 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
When we create caches in memcgs, we need to display their usage
information somewhere. We'll adopt a scheme similar to /proc/meminfo,
with aggregate totals shown in the global file, and per-group
information stored in the group itself.

For the time being, only reads are allowed in the per-group cache.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 8 ++++++++
include/linux/slab.h | 4 ++++
mm/memcontrol.c | 27 ++++++++++++++++++++++++++-
mm/slab.h | 27 +++++++++++++++++++++++++++
mm/slab_common.c | 42 ++++++++++++++++++++++++++++++++++++++----
5 files changed, 103 insertions(+), 5 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 5c1d234..14def0b 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -404,6 +404,11 @@ void sock_update_memcg(struct sock *sk);
void sock_release_memcg(struct sock *sk);

extern struct static_key memcg_kmem_enabled_key;
+
+extern int memcg_limited_groups_array_size;
+#define for_each_memcg_cache_index(_idx) \
+ for ((_idx) = 0; i < memcg_limited_groups_array_size; (_idx)++)
+
static inline bool memcg_kmem_enabled(void)
{
return static_key_false(&memcg_kmem_enabled_key);
@@ -537,6 +542,9 @@ static inline void sock_release_memcg(struct sock *sk)
{
}

+#define for_each_memcg_cache_index(_idx) \
+ for (; NULL; )
+
static inline bool memcg_kmem_enabled(void)
{
return false;
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 4a3a749..b521426 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -219,6 +219,10 @@ struct memcg_cache_params {

int memcg_update_all_caches(int num_memcgs);

+struct seq_file;
+int cache_show(struct kmem_cache *s, struct seq_file *m);
+void print_slabinfo_header(struct seq_file *m);
+
/*
* Common kmalloc functions provided by all allocators
*/
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c7732fa..e7f3458 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -551,7 +551,7 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
#endif

#ifdef CONFIG_MEMCG_KMEM
-static int memcg_limited_groups_array_size;
+int memcg_limited_groups_array_size;
#define MEMCG_CACHES_MIN_SIZE 64
/*
* MAX_SIZE should be as large as the number of css_ids. Ideally, we could get
@@ -2724,6 +2724,27 @@ static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
(memcg->kmem_account_flags & KMEM_ACCOUNTED_MASK);
}

+
+static int mem_cgroup_slabinfo_read(struct cgroup *cont, struct cftype *cft,
+ struct seq_file *m)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+ struct kmem_cache *s;
+
+ if (!memcg_can_account_kmem(memcg))
+ return -EIO;
+
+ print_slabinfo_header(m);
+
+ mutex_lock(&memcg->slab_caches_mutex);
+ list_for_each_entry(s, &memcg->memcg_slab_caches, list)
+ cache_show(s, m);
+
+ mutex_unlock(&memcg->slab_caches_mutex);
+
+ return 0;
+}
+
static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
{
struct res_counter *fail_res;
@@ -5687,6 +5708,10 @@ static struct cftype mem_cgroup_files[] = {
.trigger = mem_cgroup_reset,
.read = mem_cgroup_read,
},
+ {
+ .name = "kmem.slabinfo",
+ .read_seq_string = mem_cgroup_slabinfo_read,
+ },
#endif
{ }, /* terminate */
};
diff --git a/mm/slab.h b/mm/slab.h
index ab57462..c60f649 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -131,6 +131,23 @@ static inline bool slab_equal_or_root(struct kmem_cache *s,
return (p == s) ||
(s->memcg_params && (p == s->memcg_params->root_cache));
}
+
+/*
+ * We use suffixes to the name in memcg because we can't have caches
+ * created in the system with the same name. But when we print them
+ * locally, better refer to them with the base name
+ */
+static inline const char *cache_name(struct kmem_cache *s)
+{
+ if (!is_root_cache(s))
+ return s->memcg_params->root_cache->name;
+ return s->name;
+}
+
+static inline struct kmem_cache *cache_from_memcg(struct kmem_cache *s, int idx)
+{
+ return s->memcg_params->memcg_caches[idx];
+}
#else
static inline bool is_root_cache(struct kmem_cache *s)
{
@@ -156,5 +173,15 @@ static inline bool slab_equal_or_root(struct kmem_cache *s,
{
return true;
}
+
+static inline const char *cache_name(struct kmem_cache *s)
+{
+ return s->name;
+}
+
+static inline struct kmem_cache *cache_from_memcg(struct kmem_cache *s, int idx)
+{
+ return NULL;
+}
#endif
#endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index c02faf5..7e6d503 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -247,7 +247,7 @@ int slab_is_available(void)
}

#ifdef CONFIG_SLABINFO
-static void print_slabinfo_header(struct seq_file *m)
+void print_slabinfo_header(struct seq_file *m)
{
/*
* Output format version, so at least we can change it
@@ -291,16 +291,43 @@ static void s_stop(struct seq_file *m, void *p)
mutex_unlock(&slab_mutex);
}

-static int s_show(struct seq_file *m, void *p)
+static void
+memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
+{
+ struct kmem_cache *c;
+ struct slabinfo sinfo;
+ int i;
+
+ if (!is_root_cache(s))
+ return;
+
+ for_each_memcg_cache_index(i) {
+ c = cache_from_memcg(s, i);
+ if (!c)
+ continue;
+
+ memset(&sinfo, 0, sizeof(sinfo));
+ get_slabinfo(c, &sinfo);
+
+ info->active_slabs += sinfo.active_slabs;
+ info->num_slabs += sinfo.num_slabs;
+ info->shared_avail += sinfo.shared_avail;
+ info->active_objs += sinfo.active_objs;
+ info->num_objs += sinfo.num_objs;
+ }
+}
+
+int cache_show(struct kmem_cache *s, struct seq_file *m)
{
- struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
struct slabinfo sinfo;

memset(&sinfo, 0, sizeof(sinfo));
get_slabinfo(s, &sinfo);

+ memcg_accumulate_slabinfo(s, &sinfo);
+
seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
- s->name, sinfo.active_objs, sinfo.num_objs, s->size,
+ cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
sinfo.objects_per_slab, (1 << sinfo.cache_order));

seq_printf(m, " : tunables %4u %4u %4u",
@@ -312,6 +339,13 @@ static int s_show(struct seq_file *m, void *p)
return 0;
}

+static int s_show(struct seq_file *m, void *p)
+{
+ struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
+
+ return cache_show(s, m);
+}
+
/*
* slabinfo_op - iterator that generates /proc/slabinfo
*
--
1.7.11.7
[PATCH v5 08/18] memcg: infrastructure to match an allocation to the right cache [message #48533 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
The page allocator is able to bind a page to a memcg when it is
allocated. But for the caches, we'd like to have as many objects as
possible in a page belonging to the same cache.

This is done in this patch by calling memcg_kmem_get_cache in the
beginning of every allocation function. This routing is patched out by
static branches when kernel memory controller is not being used.

It assumes that the task allocating, which determines the memcg in the
page allocator, belongs to the same cgroup throughout the whole process.
Misacounting can happen if the task calls memcg_kmem_get_cache() while
belonging to a cgroup, and later on changes. This is considered
acceptable, and should only happen upon task migration.

Before the cache is created by the memcg core, there is also a possible
imbalance: the task belongs to a memcg, but the cache being allocated
from is the global cache, since the child cache is not yet guaranteed to
be ready. This case is also fine, since in this case the GFP_KMEMCG will
not be passed and the page allocator will not attempt any cgroup
accounting.

[ v4: use a standard workqueue mechanism, create right away if
possible, index from cache side ]

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 41 ++++++++++
init/Kconfig | 2 +-
mm/memcontrol.c | 186 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 228 insertions(+), 1 deletion(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 491d96c..92fc47a 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -422,6 +422,10 @@ void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep);

int memcg_update_cache_size(struct kmem_cache *s, int num_groups);
void memcg_update_array_size(int num_groups);
+
+struct kmem_cache *
+__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
+
/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
* @gfp: the gfp allocation flags.
@@ -491,6 +495,37 @@ memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, int order)
__memcg_kmem_commit_charge(page, memcg, order);
}

+/**
+ * memcg_kmem_get_cache: selects the correct per-memcg cache for allocation
+ * @cachep: the original global kmem cache
+ * @gfp: allocation flags.
+ *
+ * This function assumes that the task allocating, which determines the memcg
+ * in the page allocator, belongs to the same cgroup throughout the whole
+ * process. Misacounting can happen if the task calls memcg_kmem_get_cache()
+ * while belonging to a cgroup, and later on changes. This is considered
+ * acceptable, and should only happen upon task migration.
+ *
+ * Before the cache is created by the memcg core, there is also a possible
+ * imbalance: the task belongs to a memcg, but the cache being allocated from
+ * is the global cache, since the child cache is not yet guaranteed to be
+ * ready. This case is also fine, since in this case the GFP_KMEMCG will not be
+ * passed and the page allocator will not attempt any cgroup accounting.
+ */
+static __always_inline struct kmem_cache *
+memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
+{
+ if (!memcg_kmem_enabled())
+ return cachep;
+ if (gfp & __GFP_NOFAIL)
+ return cachep;
+ if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
+ return cachep;
+ if (unlikely(fatal_signal_pending(current)))
+ return cachep;
+
+ return __memcg_kmem_get_cache(cachep, gfp);
+}
#else
static inline void sock_update_memcg(struct sock *sk)
{
@@ -529,6 +564,12 @@ static inline void memcg_cache_list_add(struct mem_cgroup *memcg,
{
BUG();
}
+
+static inline struct kmem_cache *
+memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
+{
+ return cachep;
+}
#endif /* CONFIG_MEMCG_KMEM */
#endif /* _LINUX_MEMCONTROL_H */

diff --git a/init/Kconfig b/init/Kconfig
index af6c7f8..62b1f28 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -741,7 +741,7 @@ config MEMCG_SWAP_ENABLED
then swapaccount=0 does the trick).
config MEMCG_KMEM
bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
- depends on MEMCG && EXPERIMENTAL
+ depends on MEMCG && EXPERIMENTAL && !SLOB
default n
help
The Kernel Memory extension for Memory Resource Controller can limit
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index dd6ac6a..ac2e621 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -562,7 +562,14 @@ static int memcg_limited_groups_array_size;
*/
#define MEMCG_CACHES_MAX_SIZE 65535

+/*
+ * A lot of the calls to the cache allocation functions are expected to be
+ * inlined by the compiler. Since the calls to memcg_kmem_get_cache are
+ * conditional to this static branch, we'll have to allow modules that does
+ * kmem_cache_alloc and the such to see this symbol as well
+ */
struct static_key memcg_kmem_enabled_key;
+EXPORT_SYMBOL(memcg_kmem_enabled_key);

static void disarm_kmem_keys(struct mem_cgroup *memcg)
{
@@ -2930,9 +2937,188 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)

void memcg_release_cache(struct kmem_cache *s)
{
+ struct kmem_cache *root;
+ int id = memcg_css_id(s->memcg_params->memcg);
+
+ if (s->memcg_params->is_root_cache)
+ goto out;
+
+ root = s->memcg_params->root_cache;
+ root->memcg_params->memcg_caches[id] = NULL;
+ mem_cgroup_put(s->memcg_params->memcg);
+out:
kfree(s->memcg_params);
}

+static char *memcg_cache_name(struct mem_cgroup *memcg, struct kmem_cache *cachep)
+{
+ char *name;
+ struct dentry *dentry;
+
+ rcu_read_lock();
+ dentry = rcu_dereference(memcg->css.cgroup->dentry);
+ rcu_read_unlock();
+
+ BUG_ON(dentry == NULL);
+
+ name = kasprintf(GFP_KERNEL, "%s(%d:%s)",
+ cachep->name, css_id(&memcg->css), dentry->d_name.name);
+
+ return name;
+}
+
+static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
+ struct kmem_cache *s)
+{
+ char *name;
+ struct kmem_cache *new;
+
+ name = memcg_cache_name(memcg, s);
+ if (!name)
+ return NULL;
+
+ new = kmem_cache_create_memcg(memcg, name, s->object_size, s->align,
+ (s->flags & ~SLAB_PANIC), s->ctor);
+
+ kfree(name);
+ return new;
+}
+
+/*
+ * This lock protects updaters, not readers. We want readers to be as fast as
+ * they can, and they will either see NULL or a valid cache value. Our model
+ * allow them to see NULL, in which case the root memcg will be selected.
+ *
+ * We need this lock because multiple allocations to the same cache from a non
+ * GFP_WAIT area will span more than one worker. Only one of them can create
+ * the cache.
+ */
+static DEFINE_MUTEX(memcg_cache_mutex);
+static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
+ struct kmem_cache *cachep)
+{
+ struct kmem_cache *new_cachep;
+ int idx;
+
+ BUG_ON(!memcg_can_account_kmem(memcg));
+
+ idx = memcg_css_id(memcg);
+
+ mutex_lock(&memcg_cache_mutex);
+ new_cachep = cachep->memcg_params->memcg_caches[idx];
+ if (new_cachep)
+ goto out;
+
+ new_cachep = kmem_cache_dup(memcg, cachep);
+
+ if (new_cachep == NULL) {
+ new_cachep = cachep;
+ goto out;
+ }
+
+ mem_cgroup_get(memcg);
+ cachep->memcg_params->memcg_caches[idx] = new_cachep;
+ wmb(); /* the readers won't lock, make sure everybody sees it */
+ new_cachep->memcg_params->memcg = memcg;
+ new_cachep->memcg_params->root_cache = cachep;
+out:
+ mutex_unlock(&memcg_cache_mutex);
+ return new_cachep;
+}
+
+struct create_work {
+ struct mem_cgroup *memcg;
+ struct kmem_cache *cachep;
+ struct work_struct work;
+};
+
+static void memcg_create_cache_work_func(struct work_struct *w)
+{
+ struct create_work *cw;
+
+ cw = container_of(w, struct create_work, work);
+ memcg_create_kmem_cache(cw->memcg, cw->cachep);
+ /* Drop the reference gotten when we enqueued. */
+ css_put(&cw->memcg->css);
+ kfree(cw);
+}
+
+/*
+ * Enqueue the creation of a per-memcg kmem_cache.
+ * Called with rcu_read_lock.
+ */
+static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
+ struct kmem_cache *cachep)
+{
+ struct create_work *cw;
+
+ cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT);
+ if (cw == NULL)
+ return;
+
+ /* The corresponding put will be done in the workqueue. */
+ if (!css_tryget(&memcg->css))
+ return;
+
+ cw->memcg = memcg;
+ cw->cachep = cachep;
+
+ INIT_WORK(&cw->work, memcg_create_cache_work_func);
+ schedule_work(&cw->work);
+}
+
+/*
+ * Return the kmem_cache we're supposed to use for a slab allocation.
+ * We try to use the current memcg's version of the cache.
+ *
+ * If the cache does not exist yet, if we are the first user of it,
+ * we either create it immediately, if possible, or create it asynchronously
+ * in a workqueue.
+ * In the latter case, we will let the current allocation go through with
+ * the original cache.
+ *
+ * Can't be called in interrupt context or from kernel threads.
+ * This function needs to be called with rcu_read_lock() held.
+ */
+struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
+ gfp_t gfp)
+{
+ struct mem_cgroup *memcg;
+ int idx;
+
+ if (cachep->memcg_params && cachep->memcg_params->memcg)
+ return cachep;
+
+ rcu_read_lock();
+ memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));
+ rcu_read_unlock();
+
+ if (!memcg_can_account_kmem(memcg))
+ return cachep;
+
+ idx = memcg_css_id(memcg);
+ VM_BUG_ON(idx == -1);
+
+ if (cachep->memcg_par
...

[PATCH v5 07/18] Allocate memory for memcg caches whenever a new memcg appears [message #48534 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
Every cache that is considered a root cache (basically the "original" caches,
tied to the root memcg/no-memcg) will have an array that should be large enough
to store a cache pointer per each memcg in the system.

Theoreticaly, this is as high as 1 << sizeof(css_id), which is currently in the
64k pointers range. Most of the time, we won't be using that much.

What goes in this patch, is a simple scheme to dynamically allocate such an
array, in order to minimize memory usage for memcg caches. Because we would
also like to avoid allocations all the time, at least for now, the array will
only grow. It will tend to be big enough to hold the maximum number of
kmem-limited memcgs ever achieved.

We'll allocate it to be a minimum of 64 kmem-limited memcgs. When we have more
than that, we'll start doubling the size of this array every time the limit is
reached.

Because we are only considering kmem limited memcgs, a natural point for this
to happen is when we write to the limit. At that point, we already have
set_limit_mutex held, so that will become our natural synchronization
mechanism.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 2 +
mm/memcontrol.c | 171 ++++++++++++++++++++++++++++++++++++++++-----
mm/slab_common.c | 25 +++++++
3 files changed, 181 insertions(+), 17 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 4f89a45..491d96c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -420,6 +420,8 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s);
void memcg_release_cache(struct kmem_cache *cachep);
void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep);

+int memcg_update_cache_size(struct kmem_cache *s, int num_groups);
+void memcg_update_array_size(int num_groups);
/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
* @gfp: the gfp allocation flags.
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 59f6d54..dd6ac6a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -369,9 +369,15 @@ static bool memcg_kmem_is_active(struct mem_cgroup *memcg)
return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
}

-static void memcg_kmem_set_activated(struct mem_cgroup *memcg)
+static bool memcg_kmem_set_activated(struct mem_cgroup *memcg)
{
- set_bit(KMEM_ACCOUNTED_ACTIVATED, &memcg->kmem_account_flags);
+ return !test_and_set_bit(KMEM_ACCOUNTED_ACTIVATED,
+ &memcg->kmem_account_flags);
+}
+
+static void memcg_kmem_clear_activated(struct mem_cgroup *memcg)
+{
+ clear_bit(KMEM_ACCOUNTED_ACTIVATED, &memcg->kmem_account_flags);
}

static void memcg_kmem_mark_dead(struct mem_cgroup *memcg)
@@ -545,6 +551,17 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
#endif

#ifdef CONFIG_MEMCG_KMEM
+static int memcg_limited_groups_array_size;
+#define MEMCG_CACHES_MIN_SIZE 64
+/*
+ * MAX_SIZE should be as large as the number of css_ids. Ideally, we could get
+ * this constant directly from cgroup, but it is understandable that this is
+ * better kept as an internal representation in cgroup.c
+ *
+ * As of right now, this should be enough.
+ */
+#define MEMCG_CACHES_MAX_SIZE 65535
+
struct static_key memcg_kmem_enabled_key;

static void disarm_kmem_keys(struct mem_cgroup *memcg)
@@ -2783,6 +2800,115 @@ int memcg_css_id(struct mem_cgroup *memcg)
return id;
}

+/*
+ * This ends up being protected by the set_limit mutex, during normal
+ * operation, because that is its main call site.
+ *
+ * But when we create a new cache, we can call this as well if its parent
+ * is kmem-limited. That will have to hold set_limit_mutex as well.
+ */
+int memcg_update_cache_sizes(struct mem_cgroup *memcg)
+{
+ int num, ret;
+ /*
+ * After this point, kmem_accounted (that we test atomically in
+ * the beginning of this conditional), is no longer 0. This
+ * guarantees only one process will set the following boolean
+ * to true. We don't need test_and_set because we're protected
+ * by the set_limit_mutex anyway.
+ */
+ if (!memcg_kmem_set_activated(memcg))
+ return 0;
+
+ num = memcg_css_id(memcg);
+ ret = memcg_update_all_caches(num);
+ if (ret) {
+ memcg_kmem_clear_activated(memcg);
+ return ret;
+ }
+
+ INIT_LIST_HEAD(&memcg->memcg_slab_caches);
+ mutex_init(&memcg->slab_caches_mutex);
+ return 0;
+}
+
+static size_t memcg_caches_array_size(int num_groups)
+{
+ ssize_t size;
+ if (num_groups <= 0)
+ return 0;
+
+ size = 2 * num_groups;
+ if (size < MEMCG_CACHES_MIN_SIZE)
+ size = MEMCG_CACHES_MIN_SIZE;
+ else if (size > MEMCG_CACHES_MAX_SIZE)
+ size = MEMCG_CACHES_MAX_SIZE;
+
+ return size;
+}
+
+/*
+ * We should update the current array size iff all caches updates succeed. This
+ * can only be done from the slab side. The slab mutex needs to be held when
+ * calling this.
+ */
+void memcg_update_array_size(int num)
+{
+ if (num > memcg_limited_groups_array_size)
+ memcg_limited_groups_array_size = memcg_caches_array_size(num);
+}
+
+int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
+{
+ struct memcg_cache_params *cur_params = s->memcg_params;
+
+ VM_BUG_ON(s->memcg_params && !s->memcg_params->is_root_cache);
+
+ if (num_groups > memcg_limited_groups_array_size) {
+ int i;
+ ssize_t size = memcg_caches_array_size(num_groups);
+
+ size *= sizeof(void *);
+ size += sizeof(struct memcg_cache_params);
+
+ s->memcg_params = kzalloc(size ,GFP_KERNEL);
+ if (!s->memcg_params) {
+ s->memcg_params = cur_params;
+ return -ENOMEM;
+ }
+
+ s->memcg_params->is_root_cache = true;
+
+ /*
+ * There is the chance it will be bigger than
+ * memcg_limited_groups_array_size, if we failed an allocation
+ * in a cache, in which case all caches updated before it, will
+ * have a bigger array.
+ *
+ * But if that is the case, the data after
+ * memcg_limited_groups_array_size is certainly unused
+ */
+ for (i = 0; memcg_limited_groups_array_size; i++) {
+ if (!cur_params->memcg_caches[i])
+ continue;
+ s->memcg_params->memcg_caches[i] =
+ cur_params->memcg_caches[i];
+ }
+
+ /*
+ * Ideally, we would wait until all caches succeed, and only
+ * then free the old one. But this is not worth the extra
+ * pointer per-cache we'd have to have for this.
+ *
+ * It is not a big deal if some caches are left with a size
+ * bigger than the others. And all updates will reset this
+ * anyway.
+ */
+ kfree(cur_params);
+ }
+ return 0;
+}
+
int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
{
size_t size = sizeof(struct memcg_cache_params);
@@ -2790,6 +2916,9 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
if (!memcg_kmem_enabled())
return 0;

+ if (!memcg)
+ size =+ memcg_limited_groups_array_size * sizeof(void *);
+
s->memcg_params = kzalloc(size, GFP_KERNEL);
if (!s->memcg_params)
return -ENOMEM;
@@ -4292,14 +4421,11 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val)
ret = res_counter_set_limit(&memcg->kmem, val);
VM_BUG_ON(ret);

- /*
- * After this point, kmem_accounted (that we test atomically in
- * the beginning of this conditional), is no longer 0. This
- * guarantees only one process will set the following boolean
- * to true. We don't need test_and_set because we're protected
- * by the set_limit_mutex anyway.
- */
- memcg_kmem_set_activated(memcg);
+ ret = memcg_update_cache_sizes(memcg);
+ if (ret) {
+ res_counter_set_limit(&memcg->kmem, RESOURCE_MAX);
+ goto out;
+ }
must_inc_static_branch = true;
/*
* kmem charges can outlive the cgroup. In the case of slab
@@ -4338,9 +4464,10 @@ out:
return ret;
}

-static void memcg_propagate_kmem(struct mem_cgroup *memcg,
- struct mem_cgroup *parent)
+static int memcg_propagate_kmem(struct mem_cgroup *memcg,
+ struct mem_cgroup *parent)
{
+ int ret = 0;
memcg->kmem_account_flags = parent->kmem_account_flags;
#ifdef CONFIG_MEMCG_KMEM
/*
@@ -4353,11 +4480,19 @@ static void memcg_propagate_kmem(struct mem_cgroup *memcg,
* It is a lot simpler just to do static_key_slow_inc() on every child
* that is accounted.
*/
- if (memcg_kmem_is_active(memcg)) {
- mem_cgroup_get(memcg);
- static_key_slow_inc(&memcg_kmem_enabled_key);
- }
+ if (!memcg_kmem_is_active(memcg))
+ return ret;
+
+ mutex_lock(&set_limit_mutex);
+ ret = memcg_update_cache_sizes(memcg);
+ mutex_unlock(&set_limit_mutex);
+ if (ret)
+ return ret;
+
+ mem_cgroup_get(memcg);
+ static_key_slow_inc(&memcg_kmem_enabled_key);
#endif
+ return ret;
}

/*
@@ -5446,8 +5581,10 @@ mem_cgroup_create(struct cgroup *cont)
* This refcnt will be decremented when freeing this
* mem_cgroup(see mem_cgroup_put).
*/
+ error = memcg_propagate_kmem(memcg, parent);
+ if (error)
+ goto free_out;
mem_cgroup_get(parent);
- memcg_propagate_kmem(memcg, parent);
} else {
res_counter_init(&memcg->res, NULL);
res_counter_init(&memcg->memsw, NULL);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index f97f7b8..fcf59d7 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -75,6 +75,31 @@ static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg,
}
#endif

+#ifdef CONFIG_MEMCG_KMEM
+int memcg_update_all_caches(int num_memcgs)
+{
+ struct kmem_cache *s;
+ int ret = 0;
+ mutex_lock(&slab_mutex);
+
+ list_for_each_entry(s, &slab_caches, list) {
+
...

[PATCH v5 12/18] memcg: destroy memcg caches [message #48535 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
This patch implements destruction of memcg caches. Right now,
only caches where our reference counter is the last remaining are
deleted. If there are any other reference counters around, we just
leave the caches lying around until they go away.

When that happen, a destruction function is called from the cache
code. Caches are only destroyed in process context, so we queue them
up for later processing in the general case.

[ v5: removed cachep backpointer ]

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 2 ++
include/linux/slab.h | 7 +++++++
mm/memcontrol.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++
mm/slab.c | 3 +++
mm/slab.h | 24 ++++++++++++++++++++++
mm/slub.c | 7 ++++++-
6 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index f1ecb4f..9152d49 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -426,6 +426,8 @@ void memcg_update_array_size(int num_groups);
struct kmem_cache *
__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);

+void mem_cgroup_destroy_cache(struct kmem_cache *cachep);
+
/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
* @gfp: the gfp allocation flags.
diff --git a/include/linux/slab.h b/include/linux/slab.h
index b22a158..bb698dc 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -198,6 +198,10 @@ unsigned int kmem_cache_size(struct kmem_cache *);
*
* @memcg: pointer to the memcg this cache belongs to
* @root_cache: pointer to the global, root cache, this cache was derived from
+ * @dead: set to true after the memcg dies; the cache may still be around.
+ * @nr_pages: number of pages that belongs to this cache.
+ * @destroy: worker to be called whenever we are ready, or believe we may be
+ * ready, to destroy this cache.
*/
struct memcg_cache_params {
bool is_root_cache;
@@ -206,6 +210,9 @@ struct memcg_cache_params {
struct {
struct mem_cgroup *memcg;
struct kmem_cache *root_cache;
+ bool dead;
+ atomic_t nr_pages;
+ struct work_struct destroy;
};
};
};
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 354cdf0..0359b3a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2950,6 +2950,33 @@ out:
kfree(s->memcg_params);
}

+static void kmem_cache_destroy_work_func(struct work_struct *w)
+{
+ struct kmem_cache *cachep;
+ struct memcg_cache_params *p;
+
+ p = container_of(w, struct memcg_cache_params, destroy);
+
+ VM_BUG_ON(p->is_root_cache);
+ cachep = p->root_cache;
+ cachep = cachep->memcg_params->memcg_caches[memcg_css_id(p->memcg)];
+
+ if (!atomic_read(&cachep->memcg_params->nr_pages))
+ kmem_cache_destroy(cachep);
+}
+
+void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
+{
+ if (!cachep->memcg_params->dead)
+ return;
+
+ /*
+ * We have to defer the actual destroying to a workqueue, because
+ * we might currently be in a context that cannot sleep.
+ */
+ schedule_work(&cachep->memcg_params->destroy);
+}
+
/*
* During the creation a new cache, we need to disable our accounting mechanism
* altogether. This is true even if we are not creating, but rather just
@@ -3062,6 +3089,7 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
wmb(); /* the readers won't lock, make sure everybody sees it */
new_cachep->memcg_params->memcg = memcg;
new_cachep->memcg_params->root_cache = cachep;
+ atomic_set(&new_cachep->memcg_params->nr_pages , 0);
out:
mutex_unlock(&memcg_cache_mutex);
return new_cachep;
@@ -3073,6 +3101,24 @@ struct create_work {
struct work_struct work;
};

+static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
+{
+ struct kmem_cache *cachep;
+
+ if (!memcg_kmem_is_active(memcg))
+ return;
+
+ mutex_lock(&memcg->slab_caches_mutex);
+ list_for_each_entry(cachep, &memcg->memcg_slab_caches, list) {
+
+ cachep->memcg_params->dead = true;
+ INIT_WORK(&cachep->memcg_params->destroy,
+ kmem_cache_destroy_work_func);
+ schedule_work(&cachep->memcg_params->destroy);
+ }
+ mutex_unlock(&memcg->slab_caches_mutex);
+}
+
static void memcg_create_cache_work_func(struct work_struct *w)
{
struct create_work *cw;
@@ -3276,6 +3322,10 @@ void __memcg_kmem_uncharge_pages(struct page *page, int order)
VM_BUG_ON(mem_cgroup_is_root(memcg));
memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
}
+#else
+static inline void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
+{
+}
#endif /* CONFIG_MEMCG_KMEM */

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -5875,6 +5925,7 @@ static int mem_cgroup_pre_destroy(struct cgroup *cont)
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);

+ mem_cgroup_destroy_all_caches(memcg);
return mem_cgroup_force_empty(memcg, false);
}

diff --git a/mm/slab.c b/mm/slab.c
index c6cdcc0..f29b43e4 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1911,6 +1911,7 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
if (page->pfmemalloc)
SetPageSlabPfmemalloc(page + i);
}
+ memcg_bind_pages(cachep, cachep->gfporder);

if (kmemcheck_enabled && !(cachep->flags & SLAB_NOTRACK)) {
kmemcheck_alloc_shadow(page, cachep->gfporder, flags, nodeid);
@@ -1947,6 +1948,8 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr)
__ClearPageSlab(page);
page++;
}
+
+ memcg_release_pages(cachep, cachep->gfporder);
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += nr_freed;
free_memcg_kmem_pages((unsigned long)addr, cachep->gfporder);
diff --git a/mm/slab.h b/mm/slab.h
index b9b5f1f..ab57462 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -1,5 +1,6 @@
#ifndef MM_SLAB_H
#define MM_SLAB_H
+#include <linux/memcontrol.h>
/*
* Internal slab definitions
*/
@@ -109,6 +110,21 @@ static inline bool cache_match_memcg(struct kmem_cache *cachep,
(cachep->memcg_params->memcg == memcg);
}

+static inline void memcg_bind_pages(struct kmem_cache *s, int order)
+{
+ if (!is_root_cache(s))
+ atomic_add(1 << order, &s->memcg_params->nr_pages);
+}
+
+static inline void memcg_release_pages(struct kmem_cache *s, int order)
+{
+ if (is_root_cache(s))
+ return;
+
+ if (atomic_sub_and_test((1 << order), &s->memcg_params->nr_pages))
+ mem_cgroup_destroy_cache(s);
+}
+
static inline bool slab_equal_or_root(struct kmem_cache *s,
struct kmem_cache *p)
{
@@ -127,6 +143,14 @@ static inline bool cache_match_memcg(struct kmem_cache *cachep,
return true;
}

+static inline void memcg_bind_pages(struct kmem_cache *s, int order)
+{
+}
+
+static inline void memcg_release_pages(struct kmem_cache *s, int order)
+{
+}
+
static inline bool slab_equal_or_root(struct kmem_cache *s,
struct kmem_cache *p)
{
diff --git a/mm/slub.c b/mm/slub.c
index 48b7574..b5b970b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1344,6 +1344,7 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
void *start;
void *last;
void *p;
+ int order;

BUG_ON(flags & GFP_SLAB_BUG_MASK);

@@ -1352,7 +1353,9 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
if (!page)
goto out;

+ order = compound_order(page);
inc_slabs_node(s, page_to_nid(page), page->objects);
+ memcg_bind_pages(s, order);
page->slab = s;
__SetPageSlab(page);
if (page->pfmemalloc)
@@ -1361,7 +1364,7 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
start = page_address(page);

if (unlikely(s->flags & SLAB_POISON))
- memset(start, POISON_INUSE, PAGE_SIZE << compound_order(page));
+ memset(start, POISON_INUSE, PAGE_SIZE << order);

last = start;
for_each_object(p, s, start, page->objects) {
@@ -1402,6 +1405,8 @@ static void __free_slab(struct kmem_cache *s, struct page *page)

__ClearPageSlabPfmemalloc(page);
__ClearPageSlab(page);
+
+ memcg_release_pages(s, order);
reset_page_mapcount(page);
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += pages;
--
1.7.11.7
...

[PATCH v5 16/18] slab: propagate tunables values [message #48536 is a reply to message #48518] Fri, 19 October 2012 14:20 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
SLAB allows us to tune a particular cache behavior with tunables.
When creating a new memcg cache copy, we'd like to preserve any tunables
the parent cache already had.

This could be done by an explicit call to do_tune_cpucache() after the
cache is created. But this is not very convenient now that the caches are
created from common code, since this function is SLAB-specific.

Another method of doing that is taking advantage of the fact that
do_tune_cpucache() is always called from enable_cpucache(), which is
called at cache initialization. We can just preset the values, and
then things work as expected.

It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.

This change will require us to move the assignment of root_cache in
memcg_params a bit earlier. We need this to be already set - which
memcg_kmem_register_cache will do - when we reach __kmem_cache_create()

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
CC: Tejun Heo <tj@kernel.org>
---
include/linux/memcontrol.h | 8 +++++---
include/linux/slab.h | 2 +-
mm/memcontrol.c | 10 ++++++----
mm/slab.c | 44 +++++++++++++++++++++++++++++++++++++++++---
mm/slab.h | 12 ++++++++++++
mm/slab_common.c | 7 ++++---
6 files changed, 69 insertions(+), 14 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 14def0b..9da87ff 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -421,7 +421,8 @@ void __memcg_kmem_commit_charge(struct page *page,
void __memcg_kmem_uncharge_pages(struct page *page, int order);

int memcg_css_id(struct mem_cgroup *memcg);
-int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s);
+int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
+ struct kmem_cache *root_cache);
void memcg_release_cache(struct kmem_cache *cachep);
void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep);

@@ -564,8 +565,9 @@ memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, int order)
{
}

-static inline int memcg_register_cache(struct mem_cgroup *memcg,
- struct kmem_cache *s)
+static inline int
+memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
+ struct kmem_cache *root_cache)
{
return 0;
}
diff --git a/include/linux/slab.h b/include/linux/slab.h
index b521426..f8db4e1 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -128,7 +128,7 @@ struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
void (*)(void *));
struct kmem_cache *
kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
- unsigned long, void (*)(void *));
+ unsigned long, void (*)(void *), struct kmem_cache *);
void kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e7f3458..960d758 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2939,7 +2939,8 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
return 0;
}

-int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
+int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
+ struct kmem_cache *root_cache)
{
size_t size = sizeof(struct memcg_cache_params);

@@ -2953,8 +2954,10 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
if (!s->memcg_params)
return -ENOMEM;

- if (memcg)
+ if (memcg) {
s->memcg_params->memcg = memcg;
+ s->memcg_params->root_cache = root_cache;
+ }
return 0;
}

@@ -3098,7 +3101,7 @@ static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
return NULL;

new = kmem_cache_create_memcg(memcg, name, s->object_size, s->align,
- (s->flags & ~SLAB_PANIC), s->ctor);
+ (s->flags & ~SLAB_PANIC), s->ctor, s);

if (new)
new->allocflags |= __GFP_KMEMCG;
@@ -3146,7 +3149,6 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
cachep->memcg_params->memcg_caches[idx] = new_cachep;
wmb(); /* the readers won't lock, make sure everybody sees it */
new_cachep->memcg_params->memcg = memcg;
- new_cachep->memcg_params->root_cache = cachep;
atomic_set(&new_cachep->memcg_params->nr_pages , 0);
out:
mutex_unlock(&memcg_cache_mutex);
diff --git a/mm/slab.c b/mm/slab.c
index f29b43e4..a751033 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4089,7 +4089,7 @@ static void do_ccupdate_local(void *info)
}

/* Always called with the slab_mutex held */
-static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
+static int __do_tune_cpucache(struct kmem_cache *cachep, int limit,
int batchcount, int shared, gfp_t gfp)
{
struct ccupdate_struct *new;
@@ -4132,12 +4132,48 @@ static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
return alloc_kmemlist(cachep, gfp);
}

+static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
+ int batchcount, int shared, gfp_t gfp)
+{
+ int ret;
+ struct kmem_cache *c = NULL;
+ int i = 0;
+
+ ret = __do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
+
+ if (slab_state < FULL)
+ return ret;
+
+ if ((ret < 0) || !is_root_cache(cachep))
+ return ret;
+
+ for_each_memcg_cache_index(i) {
+ c = cache_from_memcg(cachep, i);
+ if (c)
+ /* return value determined by the parent cache only */
+ __do_tune_cpucache(c, limit, batchcount, shared, gfp);
+ }
+
+ return ret;
+}
+
/* Called with slab_mutex held always */
static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
{
int err;
- int limit, shared;
+ int limit = 0;
+ int shared = 0;
+ int batchcount = 0;
+
+ if (!is_root_cache(cachep)) {
+ struct kmem_cache *root = memcg_root_cache(cachep);
+ limit = root->limit;
+ shared = root->shared;
+ batchcount = root->batchcount;
+ }

+ if (limit && shared && batchcount)
+ goto skip_setup;
/*
* The head array serves three purposes:
* - create a LIFO ordering, i.e. return objects that are cache-warm
@@ -4179,7 +4215,9 @@ static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
if (limit > 32)
limit = 32;
#endif
- err = do_tune_cpucache(cachep, limit, (limit + 1) / 2, shared, gfp);
+ batchcount = (limit + 1) / 2;
+skip_setup:
+ err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
if (err)
printk(KERN_ERR "enable_cpucache failed for %s, error %d.\n",
cachep->name, -err);
diff --git a/mm/slab.h b/mm/slab.h
index c60f649..bf599fa 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -148,6 +148,13 @@ static inline struct kmem_cache *cache_from_memcg(struct kmem_cache *s, int idx)
{
return s->memcg_params->memcg_caches[idx];
}
+
+static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
+{
+ if (is_root_cache(s))
+ return s;
+ return s->memcg_params->root_cache;
+}
#else
static inline bool is_root_cache(struct kmem_cache *s)
{
@@ -183,5 +190,10 @@ static inline struct kmem_cache *cache_from_memcg(struct kmem_cache *s, int idx)
{
return NULL;
}
+
+static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
+{
+ return s;
+}
#endif
#endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 7e6d503..0dc0c41 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -127,7 +127,8 @@ out:

struct kmem_cache *
kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
- size_t align, unsigned long flags, void (*ctor)(void *))
+ size_t align, unsigned long flags, void (*ctor)(void *),
+ struct kmem_cache *parent_cache)
{
struct kmem_cache *s = NULL;
int err = 0;
@@ -156,7 +157,7 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
s->align = align;
s->ctor = ctor;

- if (memcg_register_cache(memcg, s)) {
+ if (memcg_register_cache(memcg, s, parent_cache)) {
kmem_cache_free(kmem_cache, s);
err = -ENOMEM;
goto out_locked;
@@ -208,7 +209,7 @@ struct kmem_cache *
kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
{
- return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor);
+ return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor, NULL);
}
EXPORT_SYMBOL(kmem_cache_create);

--
1.7.11.7
...

Re: [PATCH v5 04/18] slab: don't preemptively remove element from list in cache destroy [message #48539 is a reply to message #48520] Fri, 19 October 2012 19:34 Go to previous messageGo to next message
Christoph Lameter is currently offline  Christoph Lameter
Messages: 123
Registered: September 2006
Senior Member
From: *parallels.com
On Fri, 19 Oct 2012, Glauber Costa wrote:

> I, however, see no reason why we need to do so, since we are now locked
> during the whole deletion (which wasn't necessarily true before). I
> propose a simplification in which we delete it only when there is no
> more going back, so we don't need to add it again.

Ok lets hope that holding the lock does not cause issues.

Acked-by: Christoph Lameter <cl@linux.com>
Re: [PATCH v5 10/18] sl[au]b: always get the cache from its page in kfree [message #48540 is a reply to message #48519] Fri, 19 October 2012 19:44 Go to previous messageGo to next message
Christoph Lameter is currently offline  Christoph Lameter
Messages: 123
Registered: September 2006
Senior Member
From: *parallels.com
On Fri, 19 Oct 2012, Glauber Costa wrote:

> struct page already have this information. If we start chaining
> caches, this information will always be more trustworthy than
> whatever is passed into the function

Yes it does but the information is not standardized between the allocators
yet. Coul you unify that? Come out with a struct page overlay that is as
much the same as possible. Then kfree can also be unified because the
lookup is always the same. That way you can move kfree into slab_common
and avoid modifying multiple allocators.
Re: [PATCH v5 11/18] sl[au]b: Allocate objects from memcg cache [message #48541 is a reply to message #48523] Fri, 19 October 2012 19:46 Go to previous messageGo to next message
Christoph Lameter is currently offline  Christoph Lameter
Messages: 123
Registered: September 2006
Senior Member
From: *parallels.com
On Fri, 19 Oct 2012, Glauber Costa wrote:

> We are able to match a cache allocation to a particular memcg. If the
> task doesn't change groups during the allocation itself - a rare event,
> this will give us a good picture about who is the first group to touch a
> cache page.

No that the infrastructure is being reworked currently which will allow
you to do this without much of a modification of individual allocators.
Re: [PATCH v5 14/18] memcg/sl[au]b: shrink dead caches [message #48542 is a reply to message #48529] Fri, 19 October 2012 19:47 Go to previous messageGo to next message
Christoph Lameter is currently offline  Christoph Lameter
Messages: 123
Registered: September 2006
Senior Member
From: *parallels.com
On Fri, 19 Oct 2012, Glauber Costa wrote:

> An unlikely branch is used to make sure this case does not affect
> performance in the usual slab_free path.
>
> The slab allocator has a time based reaper that would eventually get rid
> of the objects, but we can also call it explicitly, since dead caches
> are not a likely event.

This is also something that could be done from slab_common since all
allocators have kmem_cache_shrink and kmem_cache_shrink can be used to
drain the caches and free up empty slab pages.
Re: [PATCH v5 15/18] Aggregate memcg cache values in slabinfo [message #48543 is a reply to message #48532] Fri, 19 October 2012 19:50 Go to previous messageGo to next message
Christoph Lameter is currently offline  Christoph Lameter
Messages: 123
Registered: September 2006
Senior Member
From: *parallels.com
On Fri, 19 Oct 2012, Glauber Costa wrote:

> +
> +/*
> + * We use suffixes to the name in memcg because we can't have caches
> + * created in the system with the same name. But when we print them
> + * locally, better refer to them with the base name
> + */
> +static inline const char *cache_name(struct kmem_cache *s)
> +{
> + if (!is_root_cache(s))
> + return s->memcg_params->root_cache->name;
> + return s->name;
> +}

Could we avoid this uglyness? You can ID a slab cache by combining a memcg
pointer and a slabname.
Re: [PATCH v5 16/18] slab: propagate tunables values [message #48544 is a reply to message #48536] Fri, 19 October 2012 19:51 Go to previous messageGo to next message
Christoph Lameter is currently offline  Christoph Lameter
Messages: 123
Registered: September 2006
Senior Member
From: *parallels.com
On Fri, 19 Oct 2012, Glauber Costa wrote:

> SLAB allows us to tune a particular cache behavior with tunables.
> When creating a new memcg cache copy, we'd like to preserve any tunables
> the parent cache already had.

SLAB and SLUB allow tuning. Could you come up with some way to put these
things into slab common and make it flexible so that the tuning could be
used for future allocators (like SLAM etc)?
Re: [PATCH v5 14/18] memcg/sl[au]b: shrink dead caches [message #48549 is a reply to message #48542] Mon, 22 October 2012 07:37 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/19/2012 11:47 PM, Christoph Lameter wrote:
> On Fri, 19 Oct 2012, Glauber Costa wrote:
>
>> An unlikely branch is used to make sure this case does not affect
>> performance in the usual slab_free path.
>>
>> The slab allocator has a time based reaper that would eventually get rid
>> of the objects, but we can also call it explicitly, since dead caches
>> are not a likely event.
>
> This is also something that could be done from slab_common since all
> allocators have kmem_cache_shrink and kmem_cache_shrink can be used to
> drain the caches and free up empty slab pages.
>

The changelog needs to be updated. I updated the code, forgot the
changelog =(

I am actually now following Tejun's last suggestion, and no longer using
my old verify_dead code.

So I am basically calling shrink_slab every once in a while until the
cache disappears.

The only change I still need in the allocators is to count the amount of
pages they have, so I can differentiate between need-to-shrink and
need-to-destroy
Re: [PATCH v5 16/18] slab: propagate tunables values [message #48550 is a reply to message #48544] Mon, 22 October 2012 07:48 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/19/2012 11:51 PM, Christoph Lameter wrote:
> On Fri, 19 Oct 2012, Glauber Costa wrote:
>
>> SLAB allows us to tune a particular cache behavior with tunables.
>> When creating a new memcg cache copy, we'd like to preserve any tunables
>> the parent cache already had.
>
> SLAB and SLUB allow tuning. Could you come up with some way to put these
> things into slab common and make it flexible so that the tuning could be
> used for future allocators (like SLAM etc)?
>
They do, but they also do it very differently. Like slub uses sysfs,
while slab don't.

I of course fully support the integration, I just don't think this
should be a blocker for all kinds of work in the allocators. Converting
slab to sysfs seems to be a major work, that you are already tackling.
Were it simple, I believe it would be done already. Without it, this is
pretty much a fake integration...

In summary, adding this doesn't make the integration work any harder in
the future, and blocking this particular thing on sysfs integration is
unreasonable.

This being by far not central to the patchset, if this is an absolute
requirement, maybe I should just drop it for the time being so it
doesn't stall the rest of the development.
Re: [PATCH v5 04/18] slab: don't preemptively remove element from list in cache destroy [message #48551 is a reply to message #48539] Mon, 22 October 2012 08:40 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/19/2012 11:34 PM, Christoph Lameter wrote:
> On Fri, 19 Oct 2012, Glauber Costa wrote:
>
>> I, however, see no reason why we need to do so, since we are now locked
>> during the whole deletion (which wasn't necessarily true before). I
>> propose a simplification in which we delete it only when there is no
>> more going back, so we don't need to add it again.
>
> Ok lets hope that holding the lock does not cause issues.
>
> Acked-by: Christoph Lameter <cl@linux.com>
>
BTW: One of the good things about this set, is that we are naturally
exercising cache destruction a lot more than we did before. So if there
is any problem, either with this or anything related to cache
destruction, it should at least show up a lot more frequently. So far,
this does not seem to cause any problems.
Re: [PATCH v5 10/18] sl[au]b: always get the cache from its page in kfree [message #48552 is a reply to message #48540] Mon, 22 October 2012 10:13 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/19/2012 11:44 PM, Christoph Lameter wrote:
> On Fri, 19 Oct 2012, Glauber Costa wrote:
>
>> struct page already have this information. If we start chaining
>> caches, this information will always be more trustworthy than
>> whatever is passed into the function
>
> Yes it does but the information is not standardized between the allocators
> yet. Coul you unify that? Come out with a struct page overlay that is as
> much the same as possible. Then kfree can also be unified because the
> lookup is always the same. That way you can move kfree into slab_common
> and avoid modifying multiple allocators.
>

Ok, this is yet another changelog mistake from mine. This function is
not about kfree, but kmem_cache_free.

But part of your comment still applies, the page lookup can still be
common. I will take a look at that.
Re: [PATCH v5 15/18] Aggregate memcg cache values in slabinfo [message #48560 is a reply to message #48543] Mon, 22 October 2012 15:11 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: 46.39.244*
On 10/19/2012 11:50 PM, Christoph Lameter wrote:
> On Fri, 19 Oct 2012, Glauber Costa wrote:
>
>> +
>> +/*
>> + * We use suffixes to the name in memcg because we can't have caches
>> + * created in the system with the same name. But when we print them
>> + * locally, better refer to them with the base name
>> + */
>> +static inline const char *cache_name(struct kmem_cache *s)
>> +{
>> + if (!is_root_cache(s))
>> + return s->memcg_params->root_cache->name;
>> + return s->name;
>> +}
>
> Could we avoid this uglyness? You can ID a slab cache by combining a memcg
> pointer and a slabname.
>
But that is not what I want.

What I want is to show the cache by its root name in memcg-specific
slabinfo.
Re: [PATCH v5 05/18] slab/slub: struct memcg_params [message #48573 is a reply to message #48526] Tue, 23 October 2012 17:25 Go to previous messageGo to next message
JoonSoo Kim is currently offline  JoonSoo Kim
Messages: 9
Registered: September 2012
Junior Member
From: *parallels.com
Hi, Glauber.

2012/10/19 Glauber Costa <glommer@parallels.com>:
> For the kmem slab controller, we need to record some extra
> information in the kmem_cache structure.
>
> Signed-off-by: Glauber Costa <glommer@parallels.com>
> Signed-off-by: Suleiman Souhlal <suleiman@google.com>
> CC: Christoph Lameter <cl@linux.com>
> CC: Pekka Enberg <penberg@cs.helsinki.fi>
> CC: Michal Hocko <mhocko@suse.cz>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> CC: Johannes Weiner <hannes@cmpxchg.org>
> CC: Tejun Heo <tj@kernel.org>
> ---
> include/linux/slab.h | 25 +++++++++++++++++++++++++
> include/linux/slab_def.h | 3 +++
> include/linux/slub_def.h | 3 +++
> mm/slab.h | 13 +++++++++++++
> 4 files changed, 44 insertions(+)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 0dd2dfa..e4ea48a 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -177,6 +177,31 @@ unsigned int kmem_cache_size(struct kmem_cache *);
> #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
> #endif
>
> +#include <linux/workqueue.h>

Why workqueue.h is includede at this time?
It may be future use, so is it better to add it later?
Adding it at proper time makes git blame works better.
Re: [PATCH v5 06/18] consider a memcg parameter in kmem_create_cache [message #48576 is a reply to message #48525] Tue, 23 October 2012 17:50 Go to previous messageGo to next message
JoonSoo Kim is currently offline  JoonSoo Kim
Messages: 9
Registered: September 2012
Junior Member
From: *parallels.com
2012/10/19 Glauber Costa <glommer@parallels.com>:

> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 6a1e096..59f6d54 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -339,6 +339,12 @@ struct mem_cgroup {
> #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
> struct tcp_memcontrol tcp_mem;
> #endif
> +#if defined(CONFIG_MEMCG_KMEM)
> + /* analogous to slab_common's slab_caches list. per-memcg */
> + struct list_head memcg_slab_caches;
> + /* Not a spinlock, we can take a lot of time walking the list */
> + struct mutex slab_caches_mutex;
> +#endif
> };

It is better to change name of "slab_caches_mutex to something
representing slab cache mutex of memcg.

> +int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
> +{
> + size_t size = sizeof(struct memcg_cache_params);
> +
> + if (!memcg_kmem_enabled())
> + return 0;
> +
> + s->memcg_params = kzalloc(size, GFP_KERNEL);
> + if (!s->memcg_params)
> + return -ENOMEM;
> +
> + if (memcg)
> + s->memcg_params->memcg = memcg;
> + return 0;
> +}

Now, I don't read full-patchset and I have not enough knowledge about cgroup.
So I have a question.
When memcg_kmem_enable, creation kmem_cache of normal user(not
included in cgroup) also allocate memcg_params.
Is it right behavior?

> +void memcg_release_cache(struct kmem_cache *s)
> +{
> + kfree(s->memcg_params);
> +}
> +
> /*
> * We need to verify if the allocation against current->mm->owner's memcg is
> * possible for the given order. But the page is not allocated yet, so we'll
> diff --git a/mm/slab.h b/mm/slab.h
> index 5ee1851..c35ecce 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -35,12 +35,15 @@ extern struct kmem_cache *kmem_cache;
> /* Functions provided by the slab allocators */
> extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);
>
> +struct mem_cgroup;
> #ifdef CONFIG_SLUB
> -struct kmem_cache *__kmem_cache_alias(const char *name, size_t size,
> - size_t align, unsigned long flags, void (*ctor)(void *));
> +struct kmem_cache *
> +__kmem_cache_alias(struct mem_cgroup *memcg, const char *name, size_t size,
> + size_t align, unsigned long flags, void (*ctor)(void *));
> #else
> -static inline struct kmem_cache *__kmem_cache_alias(const char *name, size_t size,
> - size_t align, unsigned long flags, void (*ctor)(void *))
> +static inline struct kmem_cache *
> +__kmem_cache_alias(struct mem_cgroup *memcg, const char *name, size_t size,
> + size_t align, unsigned long flags, void (*ctor)(void *))
> { return NULL; }
> #endif
>
> @@ -98,11 +101,23 @@ static inline bool is_root_cache(struct kmem_cache *s)
> {
> return !s->memcg_params || s->memcg_params->is_root_cache;
> }
> +
> +static inline bool cache_match_memcg(struct kmem_cache *cachep,
> + struct mem_cgroup *memcg)
> +{
> + return (is_root_cache(cachep) && !memcg) ||
> + (cachep->memcg_params->memcg == memcg);
> +}

When cachep->memcg_params == NULL and memcg is not NULL, NULL pointer
deref may be occurred.
Is there no situation like above?

> #else
> static inline bool is_root_cache(struct kmem_cache *s)
> {
> return true;
> }
>
> +static inline bool cache_match_memcg(struct kmem_cache *cachep,
> + struct mem_cgroup *memcg)
> +{
> + return true;
> +}
> #endif
> #endif
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index bf4b4f1..f97f7b8 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -18,6 +18,7 @@
> #include <asm/cacheflush.h>
> #include <asm/tlbflush.h>
> #include <asm/page.h>
> +#include <linux/memcontrol.h>
>
> #include "slab.h"
>
> @@ -27,7 +28,8 @@ DEFINE_MUTEX(slab_mutex);
> struct kmem_cache *kmem_cache;
>
> #ifdef CONFIG_DEBUG_VM
> -static int kmem_cache_sanity_check(const char *name, size_t size)
> +static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
> + size_t size)
> {
> struct kmem_cache *s = NULL;
>
> @@ -53,7 +55,7 @@ static int kmem_cache_sanity_check(const char *name, size_t size)
> continue;
> }
>
> - if (!strcmp(s->name, name)) {
> + if (cache_match_memcg(s, memcg) && !strcmp(s->name, name)) {
> pr_err("%s (%s): Cache name already exists.\n",
> __func__, name);
> dump_stack();
> @@ -66,7 +68,8 @@ static int kmem_cache_sanity_check(const char *name, size_t size)
> return 0;
> }
> #else
> -static inline int kmem_cache_sanity_check(const char *name, size_t size)
> +static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg,
> + const char *name, size_t size)
> {
> return 0;
> }
> @@ -97,8 +100,9 @@ static inline int kmem_cache_sanity_check(const char *name, size_t size)
> * as davem.
> */
>
> -struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
> - unsigned long flags, void (*ctor)(void *))
> +struct kmem_cache *
> +kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
> + size_t align, unsigned long flags, void (*ctor)(void *))
> {
> struct kmem_cache *s = NULL;
> int err = 0;
> @@ -106,7 +110,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
> get_online_cpus();
> mutex_lock(&slab_mutex);
>
> - if (!kmem_cache_sanity_check(name, size) == 0)
> + if (!kmem_cache_sanity_check(memcg, name, size) == 0)
> goto out_locked;

This compare is somewhat ugly.
How about "if(kmem_cache_sanity_check(memcg, name, size))"?

> /*
> @@ -117,7 +121,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
> */
> flags &= CACHE_CREATE_MASK;
>
> - s = __kmem_cache_alias(name, size, align, flags, ctor);
> + s = __kmem_cache_alias(memcg, name, size, align, flags, ctor);
> if (s)
> goto out_locked;
>
> @@ -126,6 +130,13 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
> s->object_size = s->size = size;
> s->align = align;
> s->ctor = ctor;
> +
> + if (memcg_register_cache(memcg, s)) {
> + kmem_cache_free(kmem_cache, s);
> + err = -ENOMEM;
> + goto out_locked;
> + }
> +
> s->name = kstrdup(name, GFP_KERNEL);
> if (!s->name) {
> kmem_cache_free(kmem_cache, s);
> @@ -135,10 +146,11 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
>
> err = __kmem_cache_create(s, flags);
> if (!err) {
> -
> s->refcount = 1;
> - list_add(&s->list, &slab_caches);
> -
> + if (!memcg)
> + list_add(&s->list, &slab_caches);
> + else
> + memcg_cache_list_add(memcg, s);
> } else {
> kfree(s->name);
> kmem_cache_free(kmem_cache, s);
> @@ -166,6 +178,13 @@ out_locked:
>
> return s;
> }
> +
> +struct kmem_cache *
> +kmem_cache_create(const char *name, size_t size, size_t align,
> + unsigned long flags, void (*ctor)(void *))
> +{
> + return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor);
> +}
> EXPORT_SYMBOL(kmem_cache_create);
>
> void kmem_cache_destroy(struct kmem_cache *s)
> @@ -180,6 +199,7 @@ void kmem_cache_destroy(struct kmem_cache *s)
>
> list_del(&s->list);
>
> + memcg_release_cache(s);
> kfree(s->name);
> kmem_cache_free(kmem_cache, s);
> } else {
> diff --git a/mm/slub.c b/mm/slub.c
> index a34548e..05aefe2 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -31,6 +31,7 @@
> #include <linux/fault-inject.h>
> #include <linux/stacktrace.h>
> #include <linux/prefetch.h>
> +#include <linux/memcontrol.h>
>
> #include <trace/events/kmem.h>
>
> @@ -3880,7 +3881,7 @@ static int slab_unmergeable(struct kmem_cache *s)
> return 0;
> }
>
> -static struct kmem_cache *find_mergeable(size_t size,
> +static struct kmem_cache *find_mergeable(struct mem_cgroup *memcg, size_t size,
> size_t align, unsigned long flags, const char *name,
> void (*ctor)(void *))
> {
> @@ -3916,17 +3917,20 @@ static struct kmem_cache *find_mergeable(size_t size,
> if (s->size - size >= sizeof(void *))
> continue;
>
> + if
...

Re: [PATCH v5 16/18] slab: propagate tunables values [message #48577 is a reply to message #48550] Tue, 23 October 2012 20:44 Go to previous messageGo to next message
Christoph Lameter is currently offline  Christoph Lameter
Messages: 123
Registered: September 2006
Senior Member
From: *parallels.com
On Mon, 22 Oct 2012, Glauber Costa wrote:

> On 10/19/2012 11:51 PM, Christoph Lameter wrote:
> > On Fri, 19 Oct 2012, Glauber Costa wrote:
> >
> >> SLAB allows us to tune a particular cache behavior with tunables.
> >> When creating a new memcg cache copy, we'd like to preserve any tunables
> >> the parent cache already had.
> >
> > SLAB and SLUB allow tuning. Could you come up with some way to put these
> > things into slab common and make it flexible so that the tuning could be
> > used for future allocators (like SLAM etc)?
> >
> They do, but they also do it very differently. Like slub uses sysfs,
> while slab don't.

Well yes that is something that I also want to make more general so that
all allocators support sysfs style display of status and tuning.

> I of course fully support the integration, I just don't think this
> should be a blocker for all kinds of work in the allocators. Converting
> slab to sysfs seems to be a major work, that you are already tackling.
> Were it simple, I believe it would be done already. Without it, this is
> pretty much a fake integration...

Well there is quite a bit of infrastructure that needs to be common in
order to get this done properly. I hope we will get around to that
someday.
Re: [PATCH v5 01/18] move slabinfo processing to slab_common.c [message #48583 is a reply to message #48531] Wed, 24 October 2012 06:43 Go to previous messageGo to next message
Pekka Enberg is currently offline  Pekka Enberg
Messages: 22
Registered: November 2006
Junior Member
From: *parallels.com
On Fri, Oct 19, 2012 at 5:20 PM, Glauber Costa <glommer@parallels.com> wrote:
> This patch moves all the common machinery to slabinfo processing
> to slab_common.c. We can do better by noticing that the output is
> heavily common, and having the allocators to just provide finished
> information about this. But after this first step, this can be done
> easier.
>
> Signed-off-by: Glauber Costa <glommer@parallels.com>
> Acked-by: Christoph Lameter <cl@linux.com>
> CC: Pekka Enberg <penberg@cs.helsinki.fi>
> CC: David Rientjes <rientjes@google.com>

I've applied patches 1-3. Thanks, Glauber!
Re: [PATCH v5 04/18] slab: don't preemptively remove element from list in cache destroy [message #48584 is a reply to message #48551] Wed, 24 October 2012 06:54 Go to previous messageGo to next message
Pekka Enberg is currently offline  Pekka Enberg
Messages: 22
Registered: November 2006
Junior Member
From: *parallels.com
On Mon, Oct 22, 2012 at 11:40 AM, Glauber Costa <glommer@parallels.com> wrote:
> On 10/19/2012 11:34 PM, Christoph Lameter wrote:
>> On Fri, 19 Oct 2012, Glauber Costa wrote:
>>
>>> I, however, see no reason why we need to do so, since we are now locked
>>> during the whole deletion (which wasn't necessarily true before). I
>>> propose a simplification in which we delete it only when there is no
>>> more going back, so we don't need to add it again.
>>
>> Ok lets hope that holding the lock does not cause issues.
>>
>> Acked-by: Christoph Lameter <cl@linux.com>
>>
> BTW: One of the good things about this set, is that we are naturally
> exercising cache destruction a lot more than we did before. So if there
> is any problem, either with this or anything related to cache
> destruction, it should at least show up a lot more frequently. So far,
> this does not seem to cause any problems.

We no longer hold the mutex the whole time after. See commit 210ed9d
("mm, slab: release slab_mutex earlier in kmem_cache_destroy()") for
details.
Re: [PATCH v5 04/18] slab: don't preemptively remove element from list in cache destroy [message #48585 is a reply to message #48584] Wed, 24 October 2012 08:21 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/24/2012 10:54 AM, Pekka Enberg wrote:
> On Mon, Oct 22, 2012 at 11:40 AM, Glauber Costa <glommer@parallels.com> wrote:
>> On 10/19/2012 11:34 PM, Christoph Lameter wrote:
>>> On Fri, 19 Oct 2012, Glauber Costa wrote:
>>>
>>>> I, however, see no reason why we need to do so, since we are now locked
>>>> during the whole deletion (which wasn't necessarily true before). I
>>>> propose a simplification in which we delete it only when there is no
>>>> more going back, so we don't need to add it again.
>>>
>>> Ok lets hope that holding the lock does not cause issues.
>>>
>>> Acked-by: Christoph Lameter <cl@linux.com>
>>>
>> BTW: One of the good things about this set, is that we are naturally
>> exercising cache destruction a lot more than we did before. So if there
>> is any problem, either with this or anything related to cache
>> destruction, it should at least show up a lot more frequently. So far,
>> this does not seem to cause any problems.
>
> We no longer hold the mutex the whole time after. See commit 210ed9d
> ("mm, slab: release slab_mutex earlier in kmem_cache_destroy()") for
> details.
>
I will resubmit then.

It doesn't really change the spirit of the patch. I took a look at that
fix, and what it does, is it releases the mutex right after
kmem_cache_shutdown() succeeds. Removing from the list in there would do
the trick.
Re: [PATCH v5 06/18] consider a memcg parameter in kmem_create_cache [message #48587 is a reply to message #48576] Wed, 24 October 2012 08:42 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/23/2012 09:50 PM, JoonSoo Kim wrote:
> 2012/10/19 Glauber Costa <glommer@parallels.com>:
>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 6a1e096..59f6d54 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -339,6 +339,12 @@ struct mem_cgroup {
>> #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
>> struct tcp_memcontrol tcp_mem;
>> #endif
>> +#if defined(CONFIG_MEMCG_KMEM)
>> + /* analogous to slab_common's slab_caches list. per-memcg */
>> + struct list_head memcg_slab_caches;
>> + /* Not a spinlock, we can take a lot of time walking the list */
>> + struct mutex slab_caches_mutex;
>> +#endif
>> };
>
> It is better to change name of "slab_caches_mutex to something
> representing slab cache mutex of memcg.
>

Why do you think so? I particularly think keeping the same name is
better, because it shows us that this is a memcg version of the global
mutex, and wraps all caches. One is unlikely to confuse between them,
because one of them is a global name, and the other is always inside a
struct.

>> +int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
>> +{
>> + size_t size = sizeof(struct memcg_cache_params);
>> +
>> + if (!memcg_kmem_enabled())
>> + return 0;
>> +
>> + s->memcg_params = kzalloc(size, GFP_KERNEL);
>> + if (!s->memcg_params)
>> + return -ENOMEM;
>> +
>> + if (memcg)
>> + s->memcg_params->memcg = memcg;
>> + return 0;
>> +}
>
> Now, I don't read full-patchset and I have not enough knowledge about cgroup.
> So I have a question.
> When memcg_kmem_enable, creation kmem_cache of normal user(not
> included in cgroup) also allocate memcg_params.
> Is it right behavior?
>
Yes. I would even add that *specially* the normal kmem cache gets this.
This is where it will hold the vector of memcg caches.

Also note this only happens when a memcg becomes kmem-limited, so people
not using memcg at all won't pay this price.

This should be documented over struct memcg_params.


>> +static inline bool cache_match_memcg(struct kmem_cache *cachep,
>> + struct mem_cgroup *memcg)
>> +{
>> + return (is_root_cache(cachep) && !memcg) ||
>> + (cachep->memcg_params->memcg == memcg);
>> +}
>
> When cachep->memcg_params == NULL and memcg is not NULL, NULL pointer
> deref may be occurred.
> Is there no situation like above?
>

is_root_cache already test for this, so if this is the case, we'll exit
the conditional on that test.

Every cache without a valid memcg_params pointer is a root cache.

If memcg != NULL, and memcg_params == NULL, this is a serious bug.
I just didn't BUG(), because I really didn't see the point. It is just
added instructions, and we're unlikely to make that far in that case.

>> dump_stack();
>> @@ -66,7 +68,8 @@ static int kmem_cache_sanity_check(const char *name, size_t size)
>> return 0;
>> }
>> #else
>> -static inline int kmem_cache_sanity_check(const char *name, size_t size)
>> +static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg,
>> + const char *name, size_t size)
>> {
>> return 0;
>> }
>> @@ -97,8 +100,9 @@ static inline int kmem_cache_sanity_check(const char *name, size_t size)
>> * as davem.
>> */
>>
>> -struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
>> - unsigned long flags, void (*ctor)(void *))
>> +struct kmem_cache *
>> +kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
>> + size_t align, unsigned long flags, void (*ctor)(void *))
>> {
>> struct kmem_cache *s = NULL;
>> int err = 0;
>> @@ -106,7 +110,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
>> get_online_cpus();
>> mutex_lock(&slab_mutex);
>>
>> - if (!kmem_cache_sanity_check(name, size) == 0)
>> + if (!kmem_cache_sanity_check(memcg, name, size) == 0)
>> goto out_locked;
>
> This compare is somewhat ugly.
> How about "if(kmem_cache_sanity_check(memcg, name, size))"?
>

Well, the check was already there =)
At least it becomes clear that the only thing I am changing is that i
know pass a memcg pointer.

As for the proposed change, it gives the impression that if you succeed
in the check, you will exit the function.

At least this way, it becomes clear that you exit when you fail a
sanity_check. So taking the semantics into consideration, I don't really
dislike it.

>> {
>> @@ -3916,17 +3917,20 @@ static struct kmem_cache *find_mergeable(size_t size,
>> if (s->size - size >= sizeof(void *))
>> continue;
>>
>> + if (!cache_match_memcg(s, memcg))
>> + continue;
>> return s;
>> }
>> return NULL;
>> }
>>
>> -struct kmem_cache *__kmem_cache_alias(const char *name, size_t size,
>> - size_t align, unsigned long flags, void (*ctor)(void *))
>> +struct kmem_cache *
>> +__kmem_cache_alias(struct mem_cgroup *memcg, const char *name, size_t size,
>> + size_t align, unsigned long flags, void (*ctor)(void *))
>> {
>> struct kmem_cache *s;
>>
>> - s = find_mergeable(size, align, flags, name, ctor);
>> + s = find_mergeable(memcg, size, align, flags, name, ctor);
>> if (s) {
>> s->refcount++;
>> /*
>
> If your intention is that find_mergeable() works for memcg-slab-caches properly,
> it cannot works properly with this code.
> When memcg is not NULL, slab cache is only added to memcg's slab cache list.
> find_mergeable() only interate on original-slab-cache list.
> So memcg slab cache never be mergeable.
>

Damn, you're right. In earlier submissions, we had a single list =(
I'll have to adapt this code, thanks for spotting this!
Re: [PATCH v5 05/18] slab/slub: struct memcg_params [message #48588 is a reply to message #48573] Wed, 24 October 2012 08:42 Go to previous messageGo to next message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/23/2012 09:25 PM, JoonSoo Kim wrote:
> Hi, Glauber.
>
> 2012/10/19 Glauber Costa <glommer@parallels.com>:
>> For the kmem slab controller, we need to record some extra
>> information in the kmem_cache structure.
>>
>> Signed-off-by: Glauber Costa <glommer@parallels.com>
>> Signed-off-by: Suleiman Souhlal <suleiman@google.com>
>> CC: Christoph Lameter <cl@linux.com>
>> CC: Pekka Enberg <penberg@cs.helsinki.fi>
>> CC: Michal Hocko <mhocko@suse.cz>
>> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> CC: Johannes Weiner <hannes@cmpxchg.org>
>> CC: Tejun Heo <tj@kernel.org>
>> ---
>> include/linux/slab.h | 25 +++++++++++++++++++++++++
>> include/linux/slab_def.h | 3 +++
>> include/linux/slub_def.h | 3 +++
>> mm/slab.h | 13 +++++++++++++
>> 4 files changed, 44 insertions(+)
>>
>> diff --git a/include/linux/slab.h b/include/linux/slab.h
>> index 0dd2dfa..e4ea48a 100644
>> --- a/include/linux/slab.h
>> +++ b/include/linux/slab.h
>> @@ -177,6 +177,31 @@ unsigned int kmem_cache_size(struct kmem_cache *);
>> #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
>> #endif
>>
>> +#include <linux/workqueue.h>
>
> Why workqueue.h is includede at this time?
> It may be future use, so is it better to add it later?
> Adding it at proper time makes git blame works better.
>
It is for later, I missed this.

Thanks for spotting.
Re: [PATCH v5 08/18] memcg: infrastructure to match an allocation to the right cache [message #48605 is a reply to message #48533] Wed, 24 October 2012 18:10 Go to previous messageGo to next message
JoonSoo Kim is currently offline  JoonSoo Kim
Messages: 9
Registered: September 2012
Junior Member
From: *parallels.com
2012/10/19 Glauber Costa <glommer@parallels.com>:
> @@ -2930,9 +2937,188 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
>
> void memcg_release_cache(struct kmem_cache *s)
> {
> + struct kmem_cache *root;
> + int id = memcg_css_id(s->memcg_params->memcg);
> +
> + if (s->memcg_params->is_root_cache)
> + goto out;
> +
> + root = s->memcg_params->root_cache;
> + root->memcg_params->memcg_caches[id] = NULL;
> + mem_cgroup_put(s->memcg_params->memcg);
> +out:
> kfree(s->memcg_params);
> }

memcg_css_id should be called after checking "s->memcg_params->is_root_cache".
Because when is_root_cache == true, memcg_params has no memcg object.


> +/*
> + * This lock protects updaters, not readers. We want readers to be as fast as
> + * they can, and they will either see NULL or a valid cache value. Our model
> + * allow them to see NULL, in which case the root memcg will be selected.
> + *
> + * We need this lock because multiple allocations to the same cache from a non
> + * GFP_WAIT area will span more than one worker. Only one of them can create
> + * the cache.
> + */
> +static DEFINE_MUTEX(memcg_cache_mutex);
> +static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
> + struct kmem_cache *cachep)
> +{
> + struct kmem_cache *new_cachep;
> + int idx;
> +
> + BUG_ON(!memcg_can_account_kmem(memcg));
> +
> + idx = memcg_css_id(memcg);
> +
> + mutex_lock(&memcg_cache_mutex);
> + new_cachep = cachep->memcg_params->memcg_caches[idx];
> + if (new_cachep)
> + goto out;
> +
> + new_cachep = kmem_cache_dup(memcg, cachep);
> +
> + if (new_cachep == NULL) {
> + new_cachep = cachep;
> + goto out;
> + }
> +
> + mem_cgroup_get(memcg);
> + cachep->memcg_params->memcg_caches[idx] = new_cachep;
> + wmb(); /* the readers won't lock, make sure everybody sees it */

Is there any rmb() pair?
As far as I know, without rmb(), wmb() doesn't guarantee anything.

> + new_cachep->memcg_params->memcg = memcg;
> + new_cachep->memcg_params->root_cache = cachep;

It may be better these assignment before the statement
"cachep->memcg_params->memcg_caches[idx] = new_cachep".
Otherwise, it may produce race situation.

And assigning value to memcg_params->memcg and root_cache is redundant,
because it is already done in memcg_register_cache().

> +/*
> + * Return the kmem_cache we're supposed to use for a slab allocation.
> + * We try to use the current memcg's version of the cache.
> + *
> + * If the cache does not exist yet, if we are the first user of it,
> + * we either create it immediately, if possible, or create it asynchronously
> + * in a workqueue.
> + * In the latter case, we will let the current allocation go through with
> + * the original cache.
> + *
> + * Can't be called in interrupt context or from kernel threads.
> + * This function needs to be called with rcu_read_lock() held.
> + */
> +struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
> + gfp_t gfp)
> +{
> + struct mem_cgroup *memcg;
> + int idx;
> +
> + if (cachep->memcg_params && cachep->memcg_params->memcg)
> + return cachep;

In __memcg_kmem_get_cache, cachep may be always root cache.
So checking "cachep->memcg_params->memcg" is somewhat strange.
Is it right?


Thanks.
Re: [PATCH v5 08/18] memcg: infrastructure to match an allocation to the right cache [message #48617 is a reply to message #48605] Thu, 25 October 2012 11:05 Go to previous messageGo to previous message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
From: *parallels.com
On 10/24/2012 10:10 PM, JoonSoo Kim wrote:
> 2012/10/19 Glauber Costa <glommer@parallels.com>:
>> @@ -2930,9 +2937,188 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s)
>>
>> void memcg_release_cache(struct kmem_cache *s)
>> {
>> + struct kmem_cache *root;
>> + int id = memcg_css_id(s->memcg_params->memcg);
>> +
>> + if (s->memcg_params->is_root_cache)
>> + goto out;
>> +
>> + root = s->memcg_params->root_cache;
>> + root->memcg_params->memcg_caches[id] = NULL;
>> + mem_cgroup_put(s->memcg_params->memcg);
>> +out:
>> kfree(s->memcg_params);
>> }
>
> memcg_css_id should be called after checking "s->memcg_params->is_root_cache".
> Because when is_root_cache == true, memcg_params has no memcg object.
>

Good catch.

>> +/*
>> + * This lock protects updaters, not readers. We want readers to be as fast as
>> + * they can, and they will either see NULL or a valid cache value. Our model
>> + * allow them to see NULL, in which case the root memcg will be selected.
>> + *
>> + * We need this lock because multiple allocations to the same cache from a non
>> + * GFP_WAIT area will span more than one worker. Only one of them can create
>> + * the cache.
>> + */
>> +static DEFINE_MUTEX(memcg_cache_mutex);
>> +static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
>> + struct kmem_cache *cachep)
>> +{
>> + struct kmem_cache *new_cachep;
>> + int idx;
>> +
>> + BUG_ON(!memcg_can_account_kmem(memcg));
>> +
>> + idx = memcg_css_id(memcg);
>> +
>> + mutex_lock(&memcg_cache_mutex);
>> + new_cachep = cachep->memcg_params->memcg_caches[idx];
>> + if (new_cachep)
>> + goto out;
>> +
>> + new_cachep = kmem_cache_dup(memcg, cachep);
>> +
>> + if (new_cachep == NULL) {
>> + new_cachep = cachep;
>> + goto out;
>> + }
>> +
>> + mem_cgroup_get(memcg);
>> + cachep->memcg_params->memcg_caches[idx] = new_cachep;
>> + wmb(); /* the readers won't lock, make sure everybody sees it */
>
> Is there any rmb() pair?
> As far as I know, without rmb(), wmb() doesn't guarantee anything.
>

There should be. But it seems I missed it. Speaking of which, I should
wmb() after the NULL assignment in release cache as well.

Thanks
>> + new_cachep->memcg_params->memcg = memcg;
>> + new_cachep->memcg_params->root_cache = cachep;
>
> It may be better these assignment before the statement
> "cachep->memcg_params->memcg_caches[idx] = new_cachep".
> Otherwise, it may produce race situation.
>
> And assigning value to memcg_params->memcg and root_cache is redundant,
> because it is already done in memcg_register_cache().
>

Thanks.

As for the redundancy, for memcg you are right. For root cache,
unfortunately not. Up to this patch, this is the only reference to it.
This reference will be moved to a different location in a further patch.
But then, IIRC, I delete it from here.

>> +/*
>> + * Return the kmem_cache we're supposed to use for a slab allocation.
>> + * We try to use the current memcg's version of the cache.
>> + *
>> + * If the cache does not exist yet, if we are the first user of it,
>> + * we either create it immediately, if possible, or create it asynchronously
>> + * in a workqueue.
>> + * In the latter case, we will let the current allocation go through with
>> + * the original cache.
>> + *
>> + * Can't be called in interrupt context or from kernel threads.
>> + * This function needs to be called with rcu_read_lock() held.
>> + */
>> +struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
>> + gfp_t gfp)
>> +{
>> + struct mem_cgroup *memcg;
>> + int idx;
>> +
>> + if (cachep->memcg_params && cachep->memcg_params->memcg)
>> + return cachep;
>
> In __memcg_kmem_get_cache, cachep may be always root cache.
> So checking "cachep->memcg_params->memcg" is somewhat strange.
> Is it right?
>
>
Yes, this is somewhat paranoid, and a bit historical. We were
anticipating that we could call the allocation already with the right
cache set, and in this case we would just return it.

I think I'll just VM_BUG_ON this.

Thanks for you review here.
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