From: Joonsoo Kim <[email protected]> There is a bug report that SLAB makes extreme load average due to over 2000 kworker thread.
https://bugzilla.kernel.org/show_bug.cgi?id=172981 This issue is caused by kmemcg feature that try to create new set of kmem_caches for each memcg. Recently, kmem_cache creation is slowed by synchronize_sched() and futher kmem_cache creation is also delayed since kmem_cache creation is synchronized by a global slab_mutex lock. So, the number of kworker that try to create kmem_cache increases quitely. synchronize_sched() is for lockless access to node's shared array but it's not needed when a new kmem_cache is created. So, this patch rules out that case. Fixes: 801faf0db894 ("mm/slab: lockless decision to grow cache") Cc: [email protected] Reported-by: Doug Smythies <[email protected]> Tested-by: Doug Smythies <[email protected]> Signed-off-by: Joonsoo Kim <[email protected]> --- mm/slab.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slab.c b/mm/slab.c index 6508b4d..3c83c29 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -961,7 +961,7 @@ static int setup_kmem_cache_node(struct kmem_cache *cachep, * guaranteed to be valid until irq is re-enabled, because it will be * freed after synchronize_sched(). */ - if (force_change) + if (old_shared && force_change) synchronize_sched(); fail: -- 1.9.1
