mm: page allocator: drain per-cpu lists after direct reclaim allocation fails
authorMel Gorman <mel@csn.ul.ie>
Thu, 9 Sep 2010 23:38:18 +0000 (16:38 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 10 Sep 2010 01:57:25 +0000 (18:57 -0700)
commit9ee493ce0a60bf42c0f8fd0b0fe91df5704a1cbf
tree8dbdbf3d053281291ddc6ebe50d5d0afb5ce22d7
parentaa45484031ddee09b06350ab8528bfe5b2c76d1c
mm: page allocator: drain per-cpu lists after direct reclaim allocation fails

When under significant memory pressure, a process enters direct reclaim
and immediately afterwards tries to allocate a page.  If it fails and no
further progress is made, it's possible the system will go OOM.  However,
on systems with large amounts of memory, it's possible that a significant
number of pages are on per-cpu lists and inaccessible to the calling
process.  This leads to a process entering direct reclaim more often than
it should increasing the pressure on the system and compounding the
problem.

This patch notes that if direct reclaim is making progress but allocations
are still failing that the system is already under heavy pressure.  In
this case, it drains the per-cpu lists and tries the allocation a second
time before continuing.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/page_alloc.c