diff options
| author | Vlastimil Babka <vbabka@suse.cz> | 2026-01-23 07:52:39 +0100 |
|---|---|---|
| committer | Sasha Levin <sashal@kernel.org> | 2026-03-04 07:21:18 -0500 |
| commit | bce59008b23479b470ba07ee550c3c9b7cf2fdb8 (patch) | |
| tree | 2ee8248c53350c773f396b1e0c907586f0a45cea /mm | |
| parent | f42941d60f01ad59b1eff78b35ea33711a60a4d0 (diff) | |
mm/slab: add rcu_barrier() to kvfree_rcu_barrier_on_cache()
[ Upstream commit b55b423e8518361124ff0a9e15df431b3682ee4f ]
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: 0f35040de593 ("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>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/slab_common.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index 87bde1d8916b..0f58265ca200 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -2134,8 +2134,11 @@ EXPORT_SYMBOL_GPL(kvfree_rcu_barrier); */ void kvfree_rcu_barrier_on_cache(struct kmem_cache *s) { - if (s->cpu_sheaves) + if (s->cpu_sheaves) { flush_rcu_sheaves_on_cache(s); + rcu_barrier(); + } + /* * TODO: Introduce a version of __kvfree_rcu_barrier() that works * on a specific slab cache. |