[PATCH RFC v2 01/20] mm/slab: add rcu_barrier() to kvfree_rcu_barrier_on_cache()

[Vlastimil Babka]

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.

Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202601121442.c530bed3-lkp@xxxxxxxxx
Fixes: 0f35040de593 ("mm/slab: introduce kvfree_rcu_barrier_on_cache() for cache destruction")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
 mm/slab_common.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index eed7ea556cb1..ee994ec7f251 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -2133,8 +2133,11 @@ 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.

-- 
2.52.0