summaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
authorVincent Guittot <vincent.guittot@linaro.org>2019-12-04 19:21:40 +0100
committerPeter Zijlstra <peterz@infradead.org>2019-12-17 13:32:48 +0100
commit7ed735c33104f3c6194fbc67e3a8b6e64ae84ad1 (patch)
tree9bcff437b239abfb2cbe682f2fccf57a4719ec4d /kernel
parentc3466952ca1514158d7c16c9cfc48c27d5c5dc0f (diff)
downloadlinux-7ed735c33104f3c6194fbc67e3a8b6e64ae84ad1.tar.bz2
sched/fair: Fix find_idlest_group() to handle CPU affinity
Because of CPU affinity, the local group can be skipped which breaks the assumption that statistics are always collected for local group. With uninitialized local_sgs, the comparison is meaningless and the behavior unpredictable. This can even end up to use local pointer which is to NULL in this case. If the local group has been skipped because of CPU affinity, we return the idlest group. Fixes: 57abff067a08 ("sched/fair: Rework find_idlest_group()") Reported-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Tested-by: John Stultz <john.stultz@linaro.org> Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: mingo@redhat.com Cc: mgorman@suse.de Cc: juri.lelli@redhat.com Cc: dietmar.eggemann@arm.com Cc: bsegall@google.com Cc: qais.yousef@arm.com Link: https://lkml.kernel.org/r/1575483700-22153-1-git-send-email-vincent.guittot@linaro.org
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/fair.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 08a233e97a01..146b6c83633f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8417,6 +8417,10 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
if (!idlest)
return NULL;
+ /* The local group has been skipped because of CPU affinity */
+ if (!local)
+ return idlest;
+
/*
* If the local group is idler than the selected idlest group
* don't try and push the task.