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| author | Vladimir Davydov <vdavydov.dev@gmail.com> | 2016-12-12 16:41:29 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-12 18:55:06 -0800 |
| commit | 13583c3d3224508582ec03d881d0b68dd3ee8e10 (patch) | |
| tree | 48ca686076bb06069656111ed4321236c1e83944 | |
| parent | c62c38f6b91b87a013bccd3637c2a1850d8e590c (diff) | |
| download | linux-13583c3d3224508582ec03d881d0b68dd3ee8e10.tar.bz2 | |
mm: memcontrol: use special workqueue for creating per-memcg caches
Creating a lot of cgroups at the same time might stall all worker
threads with kmem cache creation works, because kmem cache creation is
done with the slab_mutex held. The problem was amplified by commits
801faf0db894 ("mm/slab: lockless decision to grow cache") in case of
SLAB and 81ae6d03952c ("mm/slub.c: replace kick_all_cpus_sync() with
synchronize_sched() in kmem_cache_shrink()") in case of SLUB, which
increased the maximal time the slab_mutex can be held.
To prevent that from happening, let's use a special ordered single
threaded workqueue for kmem cache creation. This shouldn't introduce
any functional changes regarding how kmem caches are created, as the
work function holds the global slab_mutex during its whole runtime
anyway, making it impossible to run more than one work at a time. By
using a single threaded workqueue, we just avoid creating a thread per
each work. Ordering is required to avoid a situation when a cgroup's
work is put off indefinitely because there are other cgroups to serve,
in other words to guarantee fairness.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=172981
Link: http://lkml.kernel.org/r/20161004131417.GC1862@esperanza
Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reported-by: Doug Smythies <dsmythies@telus.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/memcontrol.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 0f870ba43942..91dfc7c5ce8f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2154,6 +2154,8 @@ struct memcg_kmem_cache_create_work { struct work_struct work; }; +static struct workqueue_struct *memcg_kmem_cache_create_wq; + static void memcg_kmem_cache_create_func(struct work_struct *w) { struct memcg_kmem_cache_create_work *cw = @@ -2185,7 +2187,7 @@ static void __memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, cw->cachep = cachep; INIT_WORK(&cw->work, memcg_kmem_cache_create_func); - schedule_work(&cw->work); + queue_work(memcg_kmem_cache_create_wq, &cw->work); } static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, @@ -5783,6 +5785,17 @@ static int __init mem_cgroup_init(void) { int cpu, node; +#ifndef CONFIG_SLOB + /* + * Kmem cache creation is mostly done with the slab_mutex held, + * so use a special workqueue to avoid stalling all worker + * threads in case lots of cgroups are created simultaneously. + */ + memcg_kmem_cache_create_wq = + alloc_ordered_workqueue("memcg_kmem_cache_create", 0); + BUG_ON(!memcg_kmem_cache_create_wq); +#endif + hotcpu_notifier(memcg_cpu_hotplug_callback, 0); for_each_possible_cpu(cpu) |