From: Hugh Dickins <hughd@google.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Sasha Levin <sasha.levin@oracle.com>,
Petr Holasek <pholasek@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH] sched: numa: ksm: fix oops in task_numa_placment()
Date: Wed, 19 Dec 2012 17:42:16 -0800 (PST) [thread overview]
Message-ID: <alpine.LNX.2.00.1212191735530.25409@eggly.anvils> (raw)
task_numa_placement() oopsed on NULL p->mm when task_numa_fault()
got called in the handling of break_ksm() for ksmd. That might be a
peculiar case, which perhaps KSM could takes steps to avoid? but it's
more robust if task_numa_placement() allows for such a possibility.
Signed-off-by: Hugh Dickins <hughd@google.com>
---
kernel/sched/fair.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- 3.7+git/kernel/sched/fair.c 2012-12-16 16:35:08.724441527 -0800
+++ linux/kernel/sched/fair.c 2012-12-18 21:37:24.727964195 -0800
@@ -793,8 +793,11 @@ unsigned int sysctl_numa_balancing_scan_
static void task_numa_placement(struct task_struct *p)
{
- int seq = ACCESS_ONCE(p->mm->numa_scan_seq);
+ int seq;
+ if (!p->mm) /* for example, ksmd faulting in a user's mm */
+ return;
+ seq = ACCESS_ONCE(p->mm->numa_scan_seq);
if (p->numa_scan_seq == seq)
return;
p->numa_scan_seq = seq;
--
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next reply other threads:[~2012-12-20 1:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-20 1:42 Hugh Dickins [this message]
2012-12-20 1:44 ` [PATCH] ksm: make rmap walks more scalable Hugh Dickins
2012-12-20 11:17 ` Mel Gorman
2012-12-20 21:49 ` Sasha Levin
2012-12-20 22:26 ` Linus Torvalds
2012-12-20 22:40 ` Hugh Dickins
2012-12-20 22:37 ` Hugh Dickins
2012-12-20 22:43 ` Sasha Levin
2012-12-21 0:36 ` Petr Holasek
2012-12-21 2:35 ` Hugh Dickins
2012-12-20 11:14 ` [PATCH] sched: numa: ksm: fix oops in task_numa_placment() Mel Gorman
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