| /proc/*/pagemap BUG: sleeping function called from invalid context [message #11832] |
Mon, 09 April 2007 08:18  |
Alexey Dobriyan
Messages: 195
Registered: August 2006
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Senior Member |
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After
cat /proc/self/pagemap
BUG: sleeping function called from invalid context at include/asm/uaccess.h:453
in_atomic():1, irqs_disabled():0
1 lock held by cat/14183:
#0: (&mm->mmap_sem){----}, at: [<c017d17b>] pagemap_read+0x11f/0x21b
[<c01b7bc7>] copy_to_user+0x37/0x4c
[<c017cf92>] add_to_pagemap+0x49/0x6f
[<c017d034>] pagemap_pte_range+0x56/0x7e
[<c017cfde>] pagemap_pte_range+0x0/0x7e
[<c01b481d>] walk_page_range+0xf1/0x1a0
[<c017d1e3>] pagemap_read+0x187/0x21b
[<c01fdafa>] tty_write+0x1bb/0x1cc
[<c017d05c>] pagemap_read+0x0/0x21b
[<c01589b0>] vfs_read+0x72/0x95
[<c0158cce>] sys_read+0x41/0x67
[<c0103d96>] sysenter_past_esp+0x8f/0x99
[<c0103d66>] sysenter_past_esp+0x5f/0x99
=======================
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| Re: /proc/*/pagemap BUG: sleeping function called from invalid context [message #11883 is a reply to message #11832] |
Tue, 10 April 2007 20:07  |
Matt Mackall
Messages: 9
Registered: April 2007
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Junior Member |
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On Mon, Apr 09, 2007 at 12:25:54PM +0400, Alexey Dobriyan wrote:
> After
> cat /proc/self/pagemap
>
> BUG: sleeping function called from invalid context at include/asm/uaccess.h:453
> in_atomic():1, irqs_disabled():0
This should fix it:
When CONFIG_HIGHPTE is enabled, use double-buffering in pagemap to
avoid calling copy_to_user while preemption is disabled.
Tested on x86 with HIGHPTE with DEBUG_SPINLOCK_SLEEP and
PROVE_LOCKING.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Index: mm/fs/proc/task_mmu.c
============================================================ =======
--- mm.orig/fs/proc/task_mmu.c 2007-04-09 10:54:28.000000000 -0500
+++ mm/fs/proc/task_mmu.c 2007-04-10 14:47:21.000000000 -0500
@@ -535,6 +535,7 @@ struct pagemapread {
struct mm_struct *mm;
unsigned long next;
unsigned long *buf;
+ pte_t *ptebuf;
unsigned long pos;
size_t count;
int index;
@@ -573,6 +574,14 @@ static int pagemap_pte_range(pmd_t *pmd,
int err;
pte = pte_offset_map(pmd, addr);
+
+#ifdef CONFIG_HIGHPTE
+ /* copy PTE directory to temporary buffer and unmap it */
+ memcpy(pm->ptebuf, pte, PAGE_ALIGN((unsigned long)pte) - (unsigned long)pte);
+ pte_unmap(pte);
+ pte = pm->ptebuf;
+#endif
+
for (; addr != end; pte++, addr += PAGE_SIZE) {
if (addr < pm->next)
continue;
@@ -583,7 +592,11 @@ static int pagemap_pte_range(pmd_t *pmd,
if (err)
return err;
}
+
+#ifndef CONFIG_HIGHPTE
pte_unmap(pte - 1);
+#endif
+
return 0;
}
@@ -655,10 +668,16 @@ static ssize_t pagemap_read(struct file
if (!page)
goto out;
+#ifdef CONFIG_HIGHPTE
+ pm.ptebuf = kzalloc(PAGE_SIZE, GFP_USER);
+ if (!pm.ptebuf)
+ goto out_free;
+#endif
+
ret = 0;
mm = get_task_mm(task);
if (!mm)
- goto out_free;
+ goto out_freepte;
pm.mm = mm;
pm.next = addr;
@@ -681,7 +700,7 @@ static ssize_t pagemap_read(struct file
while (pm.count > 0 && vma) {
if (!ptrace_may_attach(task)) {
ret = -EIO;
- goto out;
+ goto out_mm;
}
vend = min(vma->vm_start - 1, end - 1) + 1;
ret = pagemap_fill(&pm, vend);
@@ -700,8 +719,13 @@ static ssize_t pagemap_read(struct file
if (!ret)
ret = pm.pos - src;
+out_mm:
mmput(mm);
+out_freepte:
+#ifdef CONFIG_HIGHPTE
+ kfree(pm.ptebuf);
out_free:
+#endif
kfree(page);
out:
put_task_struct(task);
--
Mathematics is the supreme nostalgia of our time.
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