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[ Upstream commitb55b423e85] After we submit the rcu_free sheaves to call_rcu() we need to make sure the rcu callbacks complete. kvfree_rcu_barrier() does that via flush_all_rcu_sheaves() but kvfree_rcu_barrier_on_cache() doesn't. Fix that. This currently causes no issues because the caches with sheaves we have are never destroyed. The problem flagged by kernel test robot was reported for a patch that enables sheaves for (almost) all caches, and occurred only with CONFIG_KASAN. Harry Yoo found the root cause [1]: It turns out the object freed by sheaf_flush_unused() was in KASAN percpu quarantine list (confirmed by dumping the list) by the time __kmem_cache_shutdown() returns an error. Quarantined objects are supposed to be flushed by kasan_cache_shutdown(), but things go wrong if the rcu callback (rcu_free_sheaf_nobarn()) is processed after kasan_cache_shutdown() finishes. That's why rcu_barrier() in __kmem_cache_shutdown() didn't help, because it's called after kasan_cache_shutdown(). Calling rcu_barrier() in kvfree_rcu_barrier_on_cache() guarantees that it'll be added to the quarantine list before kasan_cache_shutdown() is called. So it's a valid fix! [1] https://lore.kernel.org/all/aWd6f3jERlrB5yeF@hyeyoo/ Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202601121442.c530bed3-lkp@intel.com Fixes:0f35040de5("mm/slab: introduce kvfree_rcu_barrier_on_cache() for cache destruction") Cc: stable@vger.kernel.org Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Tested-by: Harry Yoo <harry.yoo@oracle.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org>
2244 lines
60 KiB
2244 lines
60 KiB