x86,mm: make pagefault killable
authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Wed, 25 May 2011 00:11:30 +0000 (17:11 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 25 May 2011 15:39:08 +0000 (08:39 -0700)
commit37b23e0525d393d48a7d59f870b3bc061a30ccdb
tree467e6fcd785108a21d836e1aad8fc1a68aa72e17
parentf62e00cc3a00bfbd394a79fc22b334c31f91bd5f
x86,mm: make pagefault killable

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>
arch/x86/mm/fault.c
include/linux/mm.h
mm/filemap.c