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=-7.0 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 autolearn=no 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 399B7C433DF for ; Thu, 16 Jul 2020 21:28:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F9F520809 for ; Thu, 16 Jul 2020 21:28:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594934909; bh=XjpmwpqQaaG73yx7/K3aj3b2qjYwIj7j4S4YgPX8vV8=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=Hzbx87OAzL0Hc3xLlSghUY5OIfJ97vc4r4BpnXUOrDw0eNNMM1iCyHvp3NPPirkhs SLyyk3WzOQ0bBzV04WpcPaH/GaCIDMpOoRg3UhTrLsJ3yC8o96ApRqtYA6nYtpDcn5 /LjdP2Jcf6RI+X4bcxgmwDlUoRuU34TZl3mU6CDk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726546AbgGPV22 (ORCPT ); Thu, 16 Jul 2020 17:28:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:38222 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726090AbgGPV21 (ORCPT ); Thu, 16 Jul 2020 17:28:27 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 D268220787; Thu, 16 Jul 2020 21:28:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594934906; bh=XjpmwpqQaaG73yx7/K3aj3b2qjYwIj7j4S4YgPX8vV8=; h=Date:From:To:Subject:In-Reply-To:From; b=0J0MnEC9RR9E4z4FzmlAXySC51JwAFjD4v0KdFXADo1sRtT8v3dYWhyL6vl446U1D WZDcNbC3L89I91XhSSrRGwFi3YL2FxDVwCN/0IyUKnIBbOoSkBR80VDNyhfR62mE5Q CQKdYRE2jIGwku+l7FHnNiV4nMTBvBzzFkdqVMZM= Date: Thu, 16 Jul 2020 14:28:25 -0700 From: Andrew Morton To: cl@linux.com, guro@fb.com, iamjoonsoo.kim@lge.com, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, shakeelb@google.com, songmuchun@bytedance.com, stable@vger.kernel.org, vbabka@suse.cz Subject: + mm-memcg-slab-fix-memory-leak-at-non-root-kmem_cache-destroy.patch added to -mm tree Message-ID: <20200716212825.AGqHB_kfq%akpm@linux-foundation.org> In-Reply-To: <20200703151445.b6a0cfee402c7c5c4651f1b1@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: memcg/slab: fix memory leak at non-root kmem_cache destroy has been added to the -mm tree. Its filename is mm-memcg-slab-fix-memory-leak-at-non-root-kmem_cache-destroy.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-slab-fix-memory-leak-at-non-root-kmem_cache-destroy.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-slab-fix-memory-leak-at-non-root-kmem_cache-destroy.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Muchun Song Subject: mm: memcg/slab: fix memory leak at non-root kmem_cache destroy 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. Link: http://lkml.kernel.org/r/20200716165103.83462-1-songmuchun@bytedance.com Fixes: 92ee383f6daa ("mm: fix race between kmem_cache destroy, create and deactivate") Signed-off-by: Muchun Song 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: Signed-off-by: Andrew Morton --- mm/slab_common.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) --- a/mm/slab_common.c~mm-memcg-slab-fix-memory-leak-at-non-root-kmem_cache-destroy +++ a/mm/slab_common.c @@ -326,6 +326,14 @@ 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; } @@ -886,12 +894,15 @@ 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) { spin_lock_irq(&memcg_kmem_wq_lock); s->memcg_params.dying = true; spin_unlock_irq(&memcg_kmem_wq_lock); +} +static void flush_memcg_workqueue(struct kmem_cache *s) +{ /* * SLAB and SLUB deactivate the kmem_caches through call_rcu. Make * sure all registered rcu callbacks have been invoked. @@ -923,10 +934,6 @@ 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) @@ -944,8 +951,6 @@ void kmem_cache_destroy(struct kmem_cach if (unlikely(!s)) return; - flush_memcg_workqueue(s); - get_online_cpus(); get_online_mems(); @@ -955,6 +960,22 @@ 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); _ Patches currently in -mm which might be from songmuchun@bytedance.com are mm-memcg-slab-fix-memory-leak-at-non-root-kmem_cache-destroy.patch mm-page_alloc-skip-setting-nodemask-when-we-are-in-interrupt.patch