From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 326A036DA12; Sat, 28 Feb 2026 17:57:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772301443; cv=none; b=UuX8iL/7ocrjxlS8+QqI0jVCc0JSZb8USl7yx/A3o3/gWvvhR7H5/fvL7gp29iD998baj7g1qQKjY+ttH/9ZQPAVu0cC/AF/AfQEzQtFu8K+seOkCVspOmv1tMP8T5uSO4xF3tBJg1dF0xOWIKtKKOa0kxg5DOc+Gg77RRGgivc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772301443; c=relaxed/simple; bh=72RPNUc/iXLcDRYOIDPFhqLI8iZaaPVe6lyiIJlNqvE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HxMPjccuKMaF5c6zwNSJ1bhOAdzEA3DEb4z/FYmkUO6PGqOdf95vGbDNWV6Ol7AcibYJ0MTNUK8ZzeU4DOc30mlsJua5/snG8G//el8MCv8WVVXU8N+K54i76+Jj+QDIId4vEGgoLTxxFAOZ9h+467Q/ul8sC/1zXLsJ5ZY+nKE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TmRxl3HJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TmRxl3HJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42982C19423; Sat, 28 Feb 2026 17:57:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772301443; bh=72RPNUc/iXLcDRYOIDPFhqLI8iZaaPVe6lyiIJlNqvE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TmRxl3HJmzU7hj0uVoH/BymOsrQGNOViqteRMU/HFlgkL0s//BLAbiWBgjyTSq4vM aCV9GtUSNIZrxnI4KTTJ+0HN+kQSN0FMW5T+RFb/9OcLntkji1WRSVHxXM3jPmXNpS qiJdgWqSuMgo2lADQJOUmo63fdAv1BX5nNGyUPtTJ7j017/DO96XuWzqrlBtuRvU19 HgEca+YkWvYaxNw638iuYThc/HeIgyIT0o0OGQSuExC4/KnuaXGiN6w3IrCFVdhbo3 MBXQ1itws3mH49RuRr554ahtNmUGLCN7U7oSVh8FfQZ8+Pb+8rXPeKPM8vYXzx7dPn s7CFm/C8OkrhA== From: Sasha Levin To: patches@lists.linux.dev Cc: Vlastimil Babka , kernel test robot , stable@vger.kernel.org, Harry Yoo , Suren Baghdasaryan , "Liam R. Howlett" , Sasha Levin Subject: [PATCH 6.18 629/752] mm/slab: add rcu_barrier() to kvfree_rcu_barrier_on_cache() Date: Sat, 28 Feb 2026 12:45:40 -0500 Message-ID: <20260228174750.1542406-629-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228174750.1542406-1-sashal@kernel.org> References: <20260228174750.1542406-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Vlastimil Babka [ 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 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 Tested-by: Harry Yoo Reviewed-by: Suren Baghdasaryan Reviewed-by: Liam R. Howlett Signed-off-by: Vlastimil Babka Signed-off-by: Sasha Levin --- 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 87bde1d8916be..0f58265ca200e 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. -- 2.51.0