[Devel] Re: [RFC][PATCH 06/16] Define is_global_init()

Serge E. Hallyn serue at us.ibm.com
Thu May 24 08:27:43 PDT 2007


Quoting sukadev at us.ibm.com (sukadev at us.ibm.com):
> 
> Subject: Define is_global_init()
> 
> From: Serge E. Hallyn <serue at 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.
> 
> Changelog:
> 
> 	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 at us.ibm.com>
> Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
> ---
>  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/m32r/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               |    4 ++--
>  arch/xtensa/mm/fault.c               |    2 +-
>  drivers/char/sysrq.c                 |    2 +-
>  include/linux/sched.h                |   13 +++----------
>  kernel/capability.c                  |    3 ++-
>  kernel/exit.c                        |    2 +-
>  kernel/kexec.c                       |    2 +-
>  kernel/pid.c                         |   21 +++++++++++++++++++++
>  kernel/sysctl.c                      |    2 +-
>  mm/oom_kill.c                        |    4 ++--
>  security/commoncap.c                 |    2 +-
>  32 files changed, 61 insertions(+), 46 deletions(-)
> 
> Index: lx26-21-mm2/arch/alpha/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/alpha/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/alpha/mm/fault.c	2007-05-22 16:59:46.000000000 -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: lx26-21-mm2/arch/arm/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/arm/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/arm/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -197,7 +197,7 @@ survive:
>  		return fault;
>  	}
> 
> -	if (!is_init(tsk))
> +	if (!is_global_init(tsk))
>  		goto out;
> 
>  	/*
> Index: lx26-21-mm2/arch/arm26/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/arm26/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/arm26/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -185,7 +185,7 @@ survive:
>  	}
> 
>  	fault = -3; /* out of memory */
> -	if (!is_init(tsk))
> +	if (!is_global_init(tsk))
>  		goto out;
> 
>  	/*
> Index: lx26-21-mm2/arch/i386/lib/usercopy.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/i386/lib/usercopy.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/i386/lib/usercopy.c	2007-05-22 16:59:46.000000000 -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(&current->mm->mmap_sem);
>  				congestion_wait(WRITE, HZ/50);
>  				goto survive;
> Index: lx26-21-mm2/arch/i386/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/i386/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/i386/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -576,7 +576,7 @@ 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: lx26-21-mm2/arch/ia64/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/ia64/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/ia64/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -279,7 +279,7 @@ 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: lx26-21-mm2/arch/m32r/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/m32r/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/m32r/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -272,7 +272,7 @@ 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: lx26-21-mm2/arch/m68k/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/m68k/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/m68k/mm/fault.c	2007-05-22 16:59:46.000000000 -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: lx26-21-mm2/arch/mips/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/mips/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/mips/mm/fault.c	2007-05-22 16:59:46.000000000 -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: lx26-21-mm2/arch/powerpc/kernel/traps.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/powerpc/kernel/traps.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/powerpc/kernel/traps.c	2007-05-22 16:59:46.000000000 -0700
> @@ -190,7 +190,7 @@ 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)) {
> +	if (is_global_init(current)) {
>  		__sighandler_t handler;
> 
>  		spin_lock_irq(&current->sighand->siglock);
> Index: lx26-21-mm2/arch/powerpc/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/powerpc/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/powerpc/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -374,7 +374,7 @@ bad_area_nosemaphore:
>   */
>  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: lx26-21-mm2/arch/powerpc/platforms/pseries/ras.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/powerpc/platforms/pseries/ras.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/powerpc/platforms/pseries/ras.c	2007-05-22 16:59:46.000000000 -0700
> @@ -332,7 +332,7 @@ static int recover_mce(struct pt_regs *r
>  		   err->disposition == RTAS_DISP_NOT_RECOVERED &&
>  		   err->target == RTAS_TARGET_MEMORY &&
>  		   err->type == RTAS_TYPE_ECC_UNCORR &&
> -		   !(current->pid == 0 || is_init(current))) {
> +		   !(current->pid == 0 || is_global_init(current))) {
>  		/* Kill off a user process with an ECC error */
>  		printk(KERN_ERR "MCE: uncorrectable ecc error for pid %d\n",
>  		       current->pid);
> Index: lx26-21-mm2/arch/ppc/kernel/traps.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/ppc/kernel/traps.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/ppc/kernel/traps.c	2007-05-22 16:59:46.000000000 -0700
> @@ -120,7 +120,7 @@ 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)) {
> +	if (is_global_init(current)) {
>  		__sighandler_t handler;
> 
>  		spin_lock_irq(&current->sighand->siglock);
> Index: lx26-21-mm2/arch/ppc/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/ppc/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/ppc/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -291,7 +291,7 @@ bad_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: lx26-21-mm2/arch/s390/lib/uaccess_pt.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/s390/lib/uaccess_pt.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/s390/lib/uaccess_pt.c	2007-05-22 16:59:46.000000000 -0700
> @@ -65,7 +65,7 @@ out:
> 
>  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: lx26-21-mm2/arch/s390/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/s390/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/s390/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -211,7 +211,7 @@ static int do_out_of_memory(struct pt_re
>  	struct mm_struct *mm = tsk->mm;
> 
>  	up_read(&mm->mmap_sem);
> -	if (is_init(tsk)) {
> +	if (is_global_init(tsk)) {
>  		yield();
>  		down_read(&mm->mmap_sem);
>  		return 1;
> Index: lx26-21-mm2/arch/sh/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/sh/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/sh/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -233,7 +233,7 @@ no_context:
>   */
>  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: lx26-21-mm2/arch/sh64/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/sh64/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/sh64/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -276,7 +276,7 @@ bad_area:
>  			show_regs(regs);
>  #endif
>  		}
> -		if (is_init(tsk)) {
> +		if (is_global_init(tsk)) {
>  			panic("INIT had user mode bad_area\n");
>  		}
>  		tsk->thread.address = address;
> @@ -318,14 +318,14 @@ no_context:
>   * us unable to handle the page fault gracefully.
>   */
>  out_of_memory:
> -	if (is_init(current)) {
> +	if (is_global_init(current)) {
>  		panic("INIT out of memory\n");
>  		yield();
>  		goto survive;
>  	}
>  	printk("fault:Out of memory\n");
>  	up_read(&mm->mmap_sem);
> -	if (is_init(current)) {
> +	if (is_global_init(current)) {
>  		yield();
>  		down_read(&mm->mmap_sem);
>  		goto survive;
> Index: lx26-21-mm2/arch/um/kernel/trap.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/um/kernel/trap.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/um/kernel/trap.c	2007-05-22 16:59:46.000000000 -0700
> @@ -120,7 +120,7 @@ out_nosemaphore:
>   * us unable to handle the page fault gracefully.
>   */
>  out_of_memory:
> -	if (is_init(current)) {
> +	if (is_global_init(current)) {
>  		up_read(&mm->mmap_sem);
>  		yield();
>  		down_read(&mm->mmap_sem);
> Index: lx26-21-mm2/arch/x86_64/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/x86_64/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/x86_64/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -223,7 +223,7 @@ static int is_errata93(struct pt_regs *r
> 
>  int unhandled_signal(struct task_struct *tsk, int sig)
>  {
> -	if (is_init(tsk))
> +	if (is_global_init(tsk))
>  		return 1;
>  	if (tsk->ptrace & PT_PTRACED)
>  		return 0;
> @@ -557,7 +557,7 @@ no_context:
>   */
>  out_of_memory:
>  	up_read(&mm->mmap_sem);
> -	if (is_init(current)) {
> +	if (is_global_init(current)) {
>  		yield();
>  		goto again;
>  	}
> Index: lx26-21-mm2/arch/xtensa/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/xtensa/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/xtensa/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -144,7 +144,7 @@ bad_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: lx26-21-mm2/drivers/char/sysrq.c
> ===================================================================
> --- lx26-21-mm2.orig/drivers/char/sysrq.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/drivers/char/sysrq.c	2007-05-22 16:59:46.000000000 -0700
> @@ -250,7 +250,7 @@ static void send_sig_all(int sig)
>  	struct task_struct *p;
> 
>  	for_each_process(p) {
> -		if (p->mm && !is_init(p))
> +		if (p->mm && !is_global_init(p))
>  			/* Not swapper, init nor kernel thread */
>  			force_sig(sig, p);
>  	}
> Index: lx26-21-mm2/include/linux/sched.h
> ===================================================================
> --- lx26-21-mm2.orig/include/linux/sched.h	2007-05-22 16:59:44.000000000 -0700
> +++ lx26-21-mm2/include/linux/sched.h	2007-05-22 16:59:46.000000000 -0700
> @@ -1171,16 +1171,9 @@ static inline int pid_alive(struct task_
>  	return p->pids[PIDTYPE_PID].pid != NULL;
>  }
> 
> -/**
> - * is_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.
> - */
> -static inline int is_init(struct task_struct *tsk)
> -{
> -	return tsk->pid == 1;
> -}
> +struct pid_namespace;
> +extern int is_global_init(struct task_struct *tsk);
> +extern int is_container_init(struct task_struct *tsk);
> 
>  extern struct pid *cad_pid;
> 
> Index: lx26-21-mm2/kernel/capability.c
> ===================================================================
> --- lx26-21-mm2.orig/kernel/capability.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/kernel/capability.c	2007-05-22 16:59:46.000000000 -0700
> @@ -12,6 +12,7 @@
>  #include <linux/module.h>
>  #include <linux/security.h>
>  #include <linux/syscalls.h>
> +#include <linux/pid_namespace.h>
>  #include <asm/uaccess.h>
> 
>  unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
> @@ -135,7 +136,7 @@ static inline int cap_set_all(kernel_cap
>       int found = 0;
> 
>       do_each_thread(g, target) {
> -             if (target == current || is_init(target))
> +             if (target == current || is_container_init(target))

Ok, this is simply conforming to the capset(2) manpage/specs, so that is
correct.  (as the only actual usage of is_container_init()).

>                       continue;
>               found = 1;
>  	     if (security_capset_check(target, effective, inheritable,
> Index: lx26-21-mm2/kernel/exit.c
> ===================================================================
> --- lx26-21-mm2.orig/kernel/exit.c	2007-05-22 16:59:42.000000000 -0700
> +++ lx26-21-mm2/kernel/exit.c	2007-05-22 16:59:46.000000000 -0700
> @@ -230,7 +230,7 @@ static int will_become_orphaned_pgrp(str
>  	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
>  		if (p == ignored_task
>  				|| p->exit_state
> -				|| is_init(p->real_parent))
> +				|| is_global_init(p->real_parent))
>  			continue;
>  		if (task_pgrp(p->real_parent) != pgrp &&
>  		    task_session(p->real_parent) == task_session(p)) {
> Index: lx26-21-mm2/kernel/kexec.c
> ===================================================================
> --- lx26-21-mm2.orig/kernel/kexec.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/kernel/kexec.c	2007-05-22 16:59:46.000000000 -0700
> @@ -42,7 +42,7 @@ struct resource crashk_res = {
> 
>  int kexec_should_crash(struct task_struct *p)
>  {
> -	if (in_interrupt() || !p->pid || is_init(p) || panic_on_oops)
> +	if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
>  		return 1;
>  	return 0;
>  }
> Index: lx26-21-mm2/kernel/sysctl.c
> ===================================================================
> --- lx26-21-mm2.orig/kernel/sysctl.c	2007-05-22 16:59:41.000000000 -0700
> +++ lx26-21-mm2/kernel/sysctl.c	2007-05-22 16:59:46.000000000 -0700
> @@ -1730,7 +1730,7 @@ int proc_dointvec_bset(ctl_table *table,
>  		return -EPERM;
>  	}
> 
> -	op = is_init(current) ? OP_SET : OP_AND;
> +	op = is_global_init(current) ? OP_SET : OP_AND;
>  	return do_proc_dointvec(table,write,filp,buffer,lenp,ppos,
>  				do_proc_dointvec_bset_conv,&op);
>  }
> Index: lx26-21-mm2/mm/oom_kill.c
> ===================================================================
> --- lx26-21-mm2.orig/mm/oom_kill.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/mm/oom_kill.c	2007-05-22 16:59:46.000000000 -0700
> @@ -222,7 +222,7 @@ static struct task_struct *select_bad_pr
>  		if (!p->mm)
>  			continue;
>  		/* skip the init task */
> -		if (is_init(p))
> +		if (is_global_init(p))
>  			continue;
> 
>  		/*
> @@ -275,7 +275,7 @@ static struct task_struct *select_bad_pr
>   */
>  static void __oom_kill_task(struct task_struct *p, int verbose)
>  {
> -	if (is_init(p)) {
> +	if (is_global_init(p)) {
>  		WARN_ON(1);
>  		printk(KERN_WARNING "tried to kill init!\n");
>  		return;
> Index: lx26-21-mm2/security/commoncap.c
> ===================================================================
> --- lx26-21-mm2.orig/security/commoncap.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/security/commoncap.c	2007-05-22 16:59:46.000000000 -0700
> @@ -306,7 +306,7 @@ void cap_bprm_apply_creds (struct linux_
>  	/* For init, we want to retain the capabilities set
>  	 * in the init_task struct. Thus we skip the usual
>  	 * capability rules */
> -	if (!is_init(current)) {
> +	if (!is_global_init(current)) {

At some point we may want to make this more baroque to allow a container
init to keep all capabilities relative to it's own container.  But we're
not there yet.

So actually this might be a good reason to finally repost the user
namespace patchset.  Ironically I was going to do it during a lull in
containers@ traffic, and I'm doing it at perhaps the highest traffic
time ever, but it would be good to discuss the semantics of having
capabilities "to a namespace" and storing those to a namespace other
than your own in your keyring.

-serge

>  		current->cap_permitted = new_permitted;
>  		current->cap_effective =
>  		    cap_intersect (new_permitted, bprm->cap_effective);
> Index: lx26-21-mm2/arch/avr32/kernel/traps.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/avr32/kernel/traps.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/avr32/kernel/traps.c	2007-05-22 16:59:46.000000000 -0700
> @@ -88,7 +88,7 @@ void _exception(long signr, struct pt_re
>  	 * 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)) {
> +	if (is_global_init(current)) {
>  		__sighandler_t handler;
> 
>  		spin_lock_irq(&current->sighand->siglock);
> Index: lx26-21-mm2/arch/avr32/mm/fault.c
> ===================================================================
> --- lx26-21-mm2.orig/arch/avr32/mm/fault.c	2007-05-22 16:58:38.000000000 -0700
> +++ lx26-21-mm2/arch/avr32/mm/fault.c	2007-05-22 16:59:46.000000000 -0700
> @@ -173,7 +173,7 @@ bad_area:
>  		if (exception_trace)
>  			printk("%s%s[%d]: segfault at %08lx pc %08lx "
>  			       "sp %08lx ecr %lu\n",
> -			       is_init(tsk) ? KERN_EMERG : KERN_INFO,
> +			       is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
>  			       tsk->comm, tsk->pid, address, regs->pc,
>  			       regs->sp, ecr);
>  		_exception(SIGSEGV, regs, code, address);
> @@ -222,7 +222,7 @@ no_context:
>  	 */
>  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;
> @@ -244,7 +244,7 @@ do_sigbus:
>  	if (exception_trace)
>  		printk("%s%s[%d]: bus error at %08lx pc %08lx "
>  		       "sp %08lx ecr %lu\n",
> -		       is_init(tsk) ? KERN_EMERG : KERN_INFO,
> +		       is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
>  		       tsk->comm, tsk->pid, address, regs->pc,
>  		       regs->sp, ecr);
> 
> Index: lx26-21-mm2/kernel/pid.c
> ===================================================================
> --- lx26-21-mm2.orig/kernel/pid.c	2007-05-22 16:59:34.000000000 -0700
> +++ lx26-21-mm2/kernel/pid.c	2007-05-22 16:59:46.000000000 -0700
> @@ -71,6 +71,27 @@ struct pid_namespace init_pid_ns = {
>  	.child_reaper = &init_task
>  };
> 
> +
> +/**
> + * 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.
> + */
> +int is_global_init(struct task_struct *tsk)
> +{
> +	return (task_active_pid_ns(tsk) == &init_pid_ns && tsk->pid == 1);
> +}
> +
> +/*
> + * is_container_init:
> + * check whether in the task is init in it's own pid namespace.
> + */
> +int is_container_init(struct task_struct *tsk)
> +{
> +	return tsk->pid == 1;
> +}
> +
>  /*
>   * Note: disable interrupts while the pidmap_lock is held as an
>   * interrupt might come in and do read_lock(&tasklist_lock).

This looks good.  Thanks, Suka.

-serge
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