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[PATCH] select_bad_process(): kill a bogus PF_DEAD/TASK_DEAD check

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The only one usage of TASK_DEAD outside of last schedule path,

select_bad_process:

	for_each_task(p) {

		if (!p->mm)
			continue;
		...
			if (p->state == TASK_DEAD)
				continue;
		...

TASK_DEAD state is set at the end of do_exit(), this means that p->mm
was already set == NULL by exit_mm(), so this task was already rejected
by 'if (!p->mm)' above.

Note also that the caller holds tasklist_lock, this means that p can't
pass exit_notify() and then set TASK_DEAD when p->mm != NULL.

Also, remove open-coded is_init().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-09-29 02:01:12 -07:00 committed by Linus Torvalds
parent c394cc9fbb
commit 28324d1df6
1 changed files with 6 additions and 6 deletions
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12
mm/oom_kill.c
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@ -206,11 +206,14 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
unsigned long points;
int releasing;
/* skip kernel threads */
/*
* skip kernel threads and tasks which have already released
* their mm.
*/
if (!p->mm)
continue;
/* skip the init task with pid == 1 */
if (p->pid == 1)
/* skip the init task */
if (is_init(p))
continue;
/*
@ -226,9 +229,6 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
p->flags & PF_EXITING;
if (releasing) {
/* TASK_DEAD tasks have already released their mm */
if (p->state == TASK_DEAD)
continue;
if (p->flags & PF_EXITING && p == current) {
chosen = p;
*ppoints = ULONG_MAX;