Messages in this thread | | | Date | Tue, 12 Jun 2018 11:33:14 +0300 | From | Vladimir Davydov <> | Subject | Re: [PATCH v4] mm: fix race between kmem_cache destroy, create and deactivate |
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On Mon, Jun 11, 2018 at 12:29:51PM -0700, Shakeel Butt wrote: > 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. > > Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Thanks.
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