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Commit b460cbc5 authored by Serge E. Hallyn's avatar Serge E. Hallyn Committed by Linus Torvalds
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pid namespaces: define is_global_init() and is_container_init() 



is_init() is an ambiguous name for the pid==1 check.  Split it into
is_global_init() and is_container_init().

A cgroup 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 cgroup if the cgroup's init has a
	  bug rather than force a kernel panic.

[akpm@linux-foundation.org: fix comment]
[sukadev@us.ibm.com: Use is_global_init() in arch/m32r/mm/fault.c]
[bunk@stusta.de: kernel/pid.c: remove unused exports]
[sukadev@us.ibm.com: Fix capability.c to work with threaded init]
Signed-off-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
Signed-off-by: default avatarSukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: default avatarPavel Emelianov <xemul@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Herbert Poetzel <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3743ca05

arch/alpha/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -188,7 +188,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr, 
	/* 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;

arch/arm/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -197,7 +197,7 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, 
	return fault;



out_of_memory:

	if (!is_init(tsk))

	if (!is_global_init(tsk))

		goto out;



	/*

arch/avr32/kernel/traps.c

+1 −1
Original line number Diff line number Diff line
@@ -89,7 +89,7 @@ void _exception(long signr, struct pt_regs *regs, int code, 
	 * 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);

arch/avr32/mm/fault.c

+3 −3
Original line number Diff line number Diff line
@@ -160,7 +160,7 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs) 
		if (exception_trace && printk_ratelimit())

			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);
@@ -209,7 +209,7 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs) 
	 */

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;
@@ -231,7 +231,7 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs) 
	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);

arch/ia64/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -274,7 +274,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re 


  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;