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x86,mm: make pagefault killable

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When an oom killing occurs, almost all processes are getting stuck at the
following two points.

	1) __alloc_pages_nodemask
	2) __lock_page_or_retry

1) is not very problematic because TIF_MEMDIE leads to an allocation
failure and getting out from page allocator.

2) is more problematic.  In an OOM situation, zones typically don't have
page cache at all and memory starvation might lead to greatly reduced IO
performance.  When a fork bomb occurs, TIF_MEMDIE tasks don't die quickly,
meaning that a fork bomb may create new process quickly rather than the
oom-killer killing it.  Then, the system may become livelocked.

This patch makes the pagefault interruptible by SIGKILL.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro
2011-05-24 17:11:30 -07:00
committed by Linus Torvalds
parent f62e00cc3a
commit 37b23e0525
3 changed files with 36 additions and 8 deletions
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12
arch/x86/mm/fault.c
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@@ -965,7 +965,7 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
struct mm_struct *mm;
int fault;
int write = error_code & PF_WRITE;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY |
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
(write ? FAULT_FLAG_WRITE : 0);
tsk = current;
@@ -1138,6 +1138,16 @@ good_area:
return;
}
/*
* Pagefault was interrupted by SIGKILL. We have no reason to
* continue pagefault.
*/
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
if (!(error_code & PF_USER))
no_context(regs, error_code, address);
return;
}
/*
* Major/minor page fault accounting is only done on the
* initial attempt. If we go through a retry, it is extremely