From: Mel Gorman <mgorman@suse.de>
Date: Mon, 7 Oct 2013 10:29:29 +0000 (+0100)
Subject: sched/numa: Prevent parallel updates to group stats during placement
X-Git-Tag: omap-for-v3.13/fixes-for-merge-window-take2~40^2~39
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7dbd13ed06513b047216a7ffc718bad9df0660f1;p=pandora-kernel.git

sched/numa: Prevent parallel updates to group stats during placement

Having multiple tasks in a group go through task_numa_placement
simultaneously can lead to a task picking a wrong node to run on, because
the group stats may be in the middle of an update. This patch avoids
parallel updates by holding the numa_group lock during placement
decisions.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-52-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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