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authorVlastimil Babka <vbabka@suse.cz>2018-04-13 15:35:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-13 17:10:27 -0700
commita9f2a846f0503e7d729f552e3ccfe2279010fe94 (patch)
tree488d32afd2afdda8666a8f2df04b488ead551cdc
parent1cbf29da3628b661379acba7b08a07ef1e5da3b5 (diff)
downloadlinux-stericsson-a9f2a846f0503e7d729f552e3ccfe2279010fe94.tar.gz
mm, slab: reschedule cache_reap() on the same CPU
cache_reap() is initially scheduled in start_cpu_timer() via schedule_delayed_work_on(). But then the next iterations are scheduled via schedule_delayed_work(), i.e. using WORK_CPU_UNBOUND. Thus since commit ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs") there is no guarantee the future iterations will run on the originally intended cpu, although it's still preferred. I was able to demonstrate this with /sys/module/workqueue/parameters/debug_force_rr_cpu. IIUC, it may also happen due to migrating timers in nohz context. As a result, some cpu's would be calling cache_reap() more frequently and others never. This patch uses schedule_delayed_work_on() with the current cpu when scheduling the next iteration. Link: http://lkml.kernel.org/r/20180411070007.32225-1-vbabka@suse.cz Fixes: ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Stephen Boyd <sboyd@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/slab.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/slab.c b/mm/slab.c
index e3a9b8e23306..2f308253c3d7 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4086,7 +4086,8 @@ next:
next_reap_node();
out:
/* Set up the next iteration */
- schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_AC));
+ schedule_delayed_work_on(smp_processor_id(), work,
+ round_jiffies_relative(REAPTIMEOUT_AC));
}
void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)