Commit d1fa83ec authored Apr 28, 2026 by Uladzislau Rezki (Sony) Committed by Herbert Xu May 05, 2026

rhashtable: Add bucket_table_free_atomic() helper



rhashtable_insert_rehash() allocates a new bucket table
with GFP_ATOMIC, as it is called from an RCU read-side
critical section.

If rhashtable_rehash_attach() then fails, the new table
is freed via kvfree(). This is unsafe, since kvfree() may
fall back to vfree() for vmalloc-backed allocations, which
can sleep and trigger:

  BUG: sleeping function called from invalid context

Add bucket_table_free_atomic(), which uses kvfree_atomic()
so the table can be freed safely from non-sleeping context.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

parent dad0d91c

lib/rhashtable.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -114,6 +114,14 @@ static void bucket_table_free(const struct bucket_table *tbl)
		kvfree(tbl);
		}

		static void bucket_table_free_atomic(const struct bucket_table *tbl)
		{
		if (tbl->nest)
		nested_bucket_table_free(tbl);

		kvfree_atomic(tbl);
		}

		static void bucket_table_free_rcu(struct rcu_head *head)
		{
		bucket_table_free(container_of(head, struct bucket_table, rcu));
		@@ -496,7 +504,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,

		err = rhashtable_rehash_attach(ht, tbl, new_tbl);
		if (err) {
		bucket_table_free(new_tbl);
		bucket_table_free_atomic(new_tbl);
		if (err == -EEXIST)
		err = 0;
		} else