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authorShakeel Butt <shakeelb@google.com>2018-06-14 15:26:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-06-15 07:55:23 +0900
commit92ee383f6daab4da5471b86f6fdaba775e6928f6 (patch)
treec4e70bb32e51df2b0f4b35c82e3dc5c4f794c663 /include
parent2bdce74412c249ac01dfe36b6b0043ffd7a5361e (diff)
mm: fix race between kmem_cache destroy, create and deactivate
The memcg kmem cache creation and deactivation (SLUB only) is asynchronous. If a root kmem cache is destroyed whose memcg cache is in the process of creation or deactivation, the kernel may crash. Example of one such crash: general protection fault: 0000 [#1] SMP PTI CPU: 1 PID: 1721 Comm: kworker/14:1 Not tainted 4.17.0-smp ... Workqueue: memcg_kmem_cache kmemcg_deactivate_workfn RIP: 0010:has_cpu_slab ... Call Trace: ? on_each_cpu_cond __kmem_cache_shrink kmemcg_cache_deact_after_rcu kmemcg_deactivate_workfn process_one_work worker_thread kthread ret_from_fork+0x35/0x40 To fix this race, on root kmem cache destruction, mark the cache as dying and flush the workqueue used for memcg kmem cache creation and deactivation. SLUB's memcg kmem cache deactivation also includes RCU callback and thus make sure all previous registered RCU callbacks have completed as well. [shakeelb@google.com: handle the RCU callbacks for SLUB deactivation] Link: http://lkml.kernel.org/r/20180611192951.195727-1-shakeelb@google.com [shakeelb@google.com: add more documentation, rename fields for readability] Link: http://lkml.kernel.org/r/20180522201336.196994-1-shakeelb@google.com [akpm@linux-foundation.org: fix build, per Shakeel] [shakeelb@google.com: v3. Instead of refcount, flush the workqueue] Link: http://lkml.kernel.org/r/20180530001204.183758-1-shakeelb@google.com Link: http://lkml.kernel.org/r/20180521174116.171846-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/slab.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 4d759e1ddc33..14e3fe4bd6a1 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -600,6 +600,7 @@ struct memcg_cache_params {
struct memcg_cache_array __rcu *memcg_caches;
struct list_head __root_caches_node;
struct list_head children;
+ bool dying;
};
struct {
struct mem_cgroup *memcg;