From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CF56C433FE for ; Mon, 27 Jul 2020 14:37:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CD67206E7 for ; Mon, 27 Jul 2020 14:37:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595860669; bh=d3kN0P0WxtjeXEhXznWA8anAD4sSuMBBhzj7YQAx3ys=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Rwsf+kpOUiazuxdNSiOB8JPOjob8iloAsHKieIS5I5BXM60uFuiqaZ2qP57Pn5yAf o+pI78o4UxZ4Z3EGviabQUjiFu6/UEOnxhxcP3dzPa4UQoc2PL4dcd/zHcvweTYLjE 2lLWNVE8+7IbwNBgDLLbYys5P5RfmCSYF3Jmahl8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729466AbgG0OMJ (ORCPT ); Mon, 27 Jul 2020 10:12:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:36180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730135AbgG0OMJ (ORCPT ); Mon, 27 Jul 2020 10:12:09 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C03BA20838; Mon, 27 Jul 2020 14:12:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595859127; bh=d3kN0P0WxtjeXEhXznWA8anAD4sSuMBBhzj7YQAx3ys=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AECSfT1tG48vXpTAYTH3hB4JAPGJOGQiy6jmgtWXx/387pBygB6B7EhSBfch65kcr j73kyIb6m9EZ4+nP/R2yJuz8ypRash0uP6G8z+K3H1LHMiQaZLnaNUx38xeY1xpXKu v4SSlP7iUg85kZMYKU4RGG7/JVnHdj4zyuBT81ws= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Muchun Song , Andrew Morton , Shakeel Butt , Roman Gushchin , Vlastimil Babka , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Linus Torvalds Subject: [PATCH 4.19 76/86] mm: memcg/slab: fix memory leak at non-root kmem_cache destroy Date: Mon, 27 Jul 2020 16:04:50 +0200 Message-Id: <20200727134918.205538211@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200727134914.312934924@linuxfoundation.org> References: <20200727134914.312934924@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Muchun Song commit d38a2b7a9c939e6d7329ab92b96559ccebf7b135 upstream. If the kmem_cache refcount is greater than one, we should not mark the root kmem_cache as dying. If we mark the root kmem_cache dying incorrectly, the non-root kmem_cache can never be destroyed. It resulted in memory leak when memcg was destroyed. We can use the following steps to reproduce. 1) Use kmem_cache_create() to create a new kmem_cache named A. 2) Coincidentally, the kmem_cache A is an alias for kmem_cache B, so the refcount of B is just increased. 3) Use kmem_cache_destroy() to destroy the kmem_cache A, just decrease the B's refcount but mark the B as dying. 4) Create a new memory cgroup and alloc memory from the kmem_cache B. It leads to create a non-root kmem_cache for allocating memory. 5) When destroy the memory cgroup created in the step 4), the non-root kmem_cache can never be destroyed. If we repeat steps 4) and 5), this will cause a lot of memory leak. So only when refcount reach zero, we mark the root kmem_cache as dying. Fixes: 92ee383f6daa ("mm: fix race between kmem_cache destroy, create and deactivate") Signed-off-by: Muchun Song Signed-off-by: Andrew Morton Reviewed-by: Shakeel Butt Acked-by: Roman Gushchin Cc: Vlastimil Babka Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Shakeel Butt Cc: Link: http://lkml.kernel.org/r/20200716165103.83462-1-songmuchun@bytedance.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/slab_common.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -310,6 +310,14 @@ int slab_unmergeable(struct kmem_cache * if (s->refcount < 0) return 1; +#ifdef CONFIG_MEMCG_KMEM + /* + * Skip the dying kmem_cache. + */ + if (s->memcg_params.dying) + return 1; +#endif + return 0; } @@ -832,12 +840,15 @@ static int shutdown_memcg_caches(struct return 0; } -static void flush_memcg_workqueue(struct kmem_cache *s) +static void memcg_set_kmem_cache_dying(struct kmem_cache *s) { mutex_lock(&slab_mutex); s->memcg_params.dying = true; mutex_unlock(&slab_mutex); +} +static void flush_memcg_workqueue(struct kmem_cache *s) +{ /* * SLUB deactivates the kmem_caches through call_rcu_sched. Make * sure all registered rcu callbacks have been invoked. @@ -858,10 +869,6 @@ static inline int shutdown_memcg_caches( { return 0; } - -static inline void flush_memcg_workqueue(struct kmem_cache *s) -{ -} #endif /* CONFIG_MEMCG_KMEM */ void slab_kmem_cache_release(struct kmem_cache *s) @@ -879,8 +886,6 @@ void kmem_cache_destroy(struct kmem_cach if (unlikely(!s)) return; - flush_memcg_workqueue(s); - get_online_cpus(); get_online_mems(); @@ -890,6 +895,22 @@ void kmem_cache_destroy(struct kmem_cach if (s->refcount) goto out_unlock; +#ifdef CONFIG_MEMCG_KMEM + memcg_set_kmem_cache_dying(s); + + mutex_unlock(&slab_mutex); + + put_online_mems(); + put_online_cpus(); + + flush_memcg_workqueue(s); + + get_online_cpus(); + get_online_mems(); + + mutex_lock(&slab_mutex); +#endif + err = shutdown_memcg_caches(s); if (!err) err = shutdown_cache(s);