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Commit f400e198 authored Sep 29, 2006 by Sukadev Bhattiprolu Committed by Linus Torvalds Sep 29, 2006

[PATCH] pidspace: is_init()

This is an updated version of Eric Biederman's is_init() patch.
(http://lkml.org/lkml/2006/2/6/280

).  It applies cleanly to 2.6.18-rc3 and
replaces a few more instances of ->pid == 1 with is_init().

Further, is_init() checks pid and thus removes dependency on Eric's other
patches for now.

Eric's original description:

	There are a lot of places in the kernel where we test for init
	because we give it special properties.  Most  significantly init
	must not die.  This results in code all over the kernel test
	->pid == 1.

	Introduce is_init to capture this case.

	With multiple pid spaces for all of the cases affected we are
	looking for only the first process on the system, not some other
	process that has pid == 1.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: <lxc-devel@lists.sourceforge.net>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 959ed340

arch/alpha/mm/fault.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -193,7 +193,7 @@ 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 (current->pid == 1) {
		if (is_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
		@@ -198,7 +198,7 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
		return fault;
		}

		if (tsk->pid != 1)
		if (!is_init(tsk))
		goto out;

		/*

arch/arm26/mm/fault.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -185,7 +185,7 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
		}

		fault = -3; /* out of memory */
		if (tsk->pid != 1)
		if (!is_init(tsk))
		goto out;

		/*

arch/i386/lib/usercopy.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -739,7 +739,7 @@ unsigned long __copy_to_user_ll(void __user to, const void from,
		retval = get_user_pages(current, current->mm,
		(unsigned long )to, 1, 1, 0, &pg, NULL);

		if (retval == -ENOMEM && current->pid == 1) {
		if (retval == -ENOMEM && is_init(current)) {
		up_read(&current->mm->mmap_sem);
		blk_congestion_wait(WRITE, HZ/50);
		goto survive;

arch/i386/mm/fault.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -589,7 +589,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
		*/
		out_of_memory:
		up_read(&mm->mmap_sem);
		if (tsk->pid == 1) {
		if (is_init(tsk)) {
		yield();
		down_read(&mm->mmap_sem);
		goto survive;