sukadev@us.ibm.com wrote:
> Subject: [PATCH 6/6] Define is_global_init() and is_container_init().
>
> From: Serge E. Hallyn <serue@us.ibm.com>
>
>
> is_init() is an ambiguous name for the pid==1 check. Split it into
> is_global_init() and is_container_init().
>
> A container init has it's tsk->pid == 1.
>
> A global init also has it's tsk->pid == 1 and it's active pid namespace
> is the init_pid_ns. But rather than check the active pid namespace,
> compare the task structure with 'init_pid_ns.child_reaper', which is
> initialized during boot to the /sbin/init process and never changes.
>
> Changelog:
>
> 2.6.22-rc4-mm2-pidns1:
> - Use 'init_pid_ns.child_reaper' to determine if a given task is the
> global init (/sbin/init) process. This would improve performance
> and remove dependence on the task_pid().
>
> 2.6.21-mm2-pidns2:
>
> - [Sukadev Bhattiprolu] Changed is_container_init() calls in {powerpc,
> ppc,avr32}/traps.c for the _exception() call to is_global_init().
> This way, we kill only the container if the container's init has a
> bug rather than force a kernel panic.
>
> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
> Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: Pavel Emelianov <xemul@openvz.org>
> ---
> arch/alpha/mm/fault.c | 2 +-
> arch/arm/mm/fault.c | 2 +-
> arch/arm26/mm/fault.c | 2 +-
> arch/avr32/kernel/traps.c | 2 +-
> arch/avr32/mm/fault.c | 6 +++---
> arch/i386/lib/usercopy.c | 2 +-
> arch/i386/mm/fault.c | 2 +-
> arch/ia64/mm/fault.c | 2 +-
> arch/m68k/mm/fault.c | 2 +-
> arch/mips/mm/fault.c | 2 +-
> arch/powerpc/kernel/traps.c | 2 +-
> arch/powerpc/mm/fault.c | 2 +-
> arch/powerpc/platforms/pseries/ras.c | 2 +-
> arch/ppc/kernel/traps.c | 2 +-
> arch/ppc/mm/fault.c | 2 +-
> arch/s390/lib/uaccess_pt.c | 2 +-
> arch/s390/mm/fault.c | 2 +-
> arch/sh/mm/fault.c | 2 +-
> arch/sh64/mm/fault.c | 6 +++---
> arch/um/kernel/trap.c | 2 +-
> arch/x86_64/mm/fault.c | 2 +-
> arch/xtensa/mm/fault.c | 2 +-
> drivers/char/sysrq.c | 2 +-
> include/linux/sched.h | 12 ++++++++++--
> kernel/capability.c | 3 ++-
> kernel/exit.c | 2 +-
> kernel/kexec.c | 2 +-
> kernel/pid.c | 5 +++++
> kernel/signal.c | 2 +-
> kernel/sysctl.c | 2 +-
> mm/oom_kill.c | 4 ++--
> security/commoncap.c | 3 ++-
> 32 files changed, 52 insertions(+), 37 deletions(-)
>
> Index: lx26-22-rc6-mm1/include/linux/sched.h
> ===================================================================
> --- lx26-22-rc6-mm1.orig/include/linux/sched.h 2007-07-05 18:57:34.000000000 -0700
> +++ lx26-22-rc6-mm1/include/linux/sched.h 2007-07-05 18:59:06.000000000 -0700
> @@ -1248,12 +1248,20 @@ static inline int pid_alive(struct task_
> }
>
> /**
> - * is_init - check if a task structure is init
> + * is_global_init - check if a task structure is init
> * @tsk: Task structure to be checked.
> *
> * Check if a task structure is the first user space task the kernel created.
> + *
> + * TODO: We should inline this function after some cleanups in pid_namespace.h
> + */
> +extern int is_global_init(struct task_struct *tsk);
> +
> +/*
> + * is_container_init:
> + * check whether in the task is init in it's own pid namespace.
> */
> -static inline int is_init(struct task_struct *tsk)
> +static inline int is_container_init(struct task_struct *tsk)
> {
> return tsk->pid == 1;
> }
> Index: lx26-22-rc6-mm1/kernel/pid.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/kernel/pid.c 2007-07-05 18:53:48.000000000 -0700
> +++ lx26-22-rc6-mm1/kernel/pid.c 2007-07-05 18:59:06.000000000 -0700
> @@ -71,6 +71,11 @@ struct pid_namespace init_pid_ns = {
> .child_reaper = &init_task
> };
>
> +int is_global_init(struct task_struct *tsk)
> +{
> + return tsk == init_pid_ns.child_reaper;
> +}
> +
> /*
> * Note: disable interrupts while the pidmap_lock is held as an
> * interrupt might come in and do read_lock(&tasklist_lock).
> Index: lx26-22-rc6-mm1/arch/alpha/mm/fault.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/alpha/mm/fault.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/alpha/mm/fault.c 2007-07-05 18:59:06.000000000 -0700
> @@ -192,7 +192,7 @@ do_page_fault(unsigned long address, uns
> /* We ran out of memory, or some other thing happened to us that
> made us unable to handle the page fault gracefully. */
> out_of_memory:
> - if (is_init(current)) {
> + if (is_global_init(current)) {
> yield();
> down_read(&mm->mmap_sem);
> goto survive;
> Index: lx26-22-rc6-mm1/arch/arm/mm/fault.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/arm/mm/fault.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/arm/mm/fault.c 2007-07-05 18:59:06.000000000 -0700
> @@ -197,7 +197,7 @@ survive:
> return fault;
> }
>
> - if (!is_init(tsk))
> + if (!is_global_init(tsk))
> goto out;
>
> /*
> Index: lx26-22-rc6-mm1/arch/arm26/mm/fault.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/arm26/mm/fault.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/arm26/mm/fault.c 2007-07-05 18:59:06.000000000 -0700
> @@ -185,7 +185,7 @@ survive:
> }
>
> fault = -3; /* out of memory */
> - if (!is_init(tsk))
> + if (!is_global_init(tsk))
> goto out;
>
> /*
> Index: lx26-22-rc6-mm1/arch/i386/lib/usercopy.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/i386/lib/usercopy.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/i386/lib/usercopy.c 2007-07-05 18:59:06.000000000 -0700
> @@ -748,7 +748,7 @@ survive:
> retval = get_user_pages(current, current->mm,
> (unsigned long )to, 1, 1, 0, &pg, NULL);
>
> - if (retval == -ENOMEM && is_init(current)) {
> + if (retval == -ENOMEM && is_global_init(current)) {
> up_read(¤t->mm->mmap_sem);
> congestion_wait(WRITE, HZ/50);
> goto survive;
> Index: lx26-22-rc6-mm1/arch/i386/mm/fault.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/i386/mm/fault.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/i386/mm/fault.c 2007-07-05 18:59:06.000000000 -0700
> @@ -595,7 +595,7 @@ no_context:
> */
> out_of_memory:
> up_read(&mm->mmap_sem);
> - if (is_init(tsk)) {
> + if (is_global_init(tsk)) {
> yield();
> down_read(&mm->mmap_sem);
> goto survive;
> Index: lx26-22-rc6-mm1/arch/ia64/mm/fault.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/ia64/mm/fault.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/ia64/mm/fault.c 2007-07-05 18:59:06.000000000 -0700
> @@ -270,7 +270,7 @@ ia64_do_page_fault (unsigned long addres
>
> out_of_memory:
> up_read(&mm->mmap_sem);
> - if (is_init(current)) {
> + if (is_global_init(current)) {
> yield();
> down_read(&mm->mmap_sem);
> goto survive;
> Index: lx26-22-rc6-mm1/arch/m68k/mm/fault.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/m68k/mm/fault.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/m68k/mm/fault.c 2007-07-05 18:59:06.000000000 -0700
> @@ -181,7 +181,7 @@ good_area:
> */
> out_of_memory:
> up_read(&mm->mmap_sem);
> - if (is_init(current)) {
> + if (is_global_init(current)) {
> yield();
> down_read(&mm->mmap_sem);
> goto survive;
> Index: lx26-22-rc6-mm1/arch/mips/mm/fault.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/mips/mm/fault.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/mips/mm/fault.c 2007-07-05 18:59:06.000000000 -0700
> @@ -174,7 +174,7 @@ no_context:
> */
> out_of_memory:
> up_read(&mm->mmap_sem);
> - if (is_init(tsk)) {
> + if (is_global_init(tsk)) {
> yield();
> down_read(&mm->mmap_sem);
> goto survive;
> Index: lx26-22-rc6-mm1/arch/powerpc/kernel/traps.c
> ===================================================================
> --- lx26-22-rc6-mm1.orig/arch/powerpc/kernel/traps.c 2007-07-05 18:53:42.000000000 -0700
> +++ lx26-22-rc6-mm1/arch/powerpc/kernel/traps.c 2007-07-05 18:59:06.000000000 -0700
> @@ -191,7 +191,7 @@ void _exception(int signr, struct pt_reg
> * generate the same exception over and over again and we get
> * nowhere. Better to kill it and let the kernel panic.
> */
> - if (is_init(current))
...