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authorHugh Dickins <hughd@google.com>2012-12-19 17:42:16 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-20 07:06:56 -0800
commit2832bc19f6668fd00116f61f821105040599ef8b (patch)
tree9839b9321ab7c3dc86f003d69cae522a78d02f20 /kernel/sched
parentcda73a10eb3f493871ed39f468db50a65ebeddce (diff)
downloadlinaro-lsk-2832bc19f6668fd00116f61f821105040599ef8b.tar.gz
sched: numa: ksm: fix oops in task_numa_placment()
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> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4603d6cb9e2..5eea8707234 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -793,8 +793,11 @@ unsigned int sysctl_numa_balancing_scan_delay = 1000;
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;