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,URIBL_BLOCKED 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 EC00CC433FB for ; Fri, 24 Jul 2020 04:15:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AF3E22064B for ; Fri, 24 Jul 2020 04:15:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="IRM/trn6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF3E22064B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5EA218D000D; Fri, 24 Jul 2020 00:15:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 59A368D0007; Fri, 24 Jul 2020 00:15:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D7228D000D; Fri, 24 Jul 2020 00:15:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 394D18D0007 for ; Fri, 24 Jul 2020 00:15:30 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id F17F018284955 for ; Fri, 24 Jul 2020 04:15:29 +0000 (UTC) X-FDA: 77071655178.06.desk33_4c0147a26f44 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin06.hostedemail.com (Postfix) with ESMTP id C71841004F864 for ; Fri, 24 Jul 2020 04:15:29 +0000 (UTC) X-HE-Tag: desk33_4c0147a26f44 X-Filterd-Recvd-Size: 5159 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Fri, 24 Jul 2020 04:15:29 +0000 (UTC) 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 05E2C206F0; Fri, 24 Jul 2020 04:15:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595564128; bh=36uabGEVHp8iUOJIoaEdlBAzyq6PceCEgUwXJtb2/i4=; h=Date:From:To:Subject:In-Reply-To:From; b=IRM/trn6NosK6amrxCIksIYw8rfxl3FppTMhnwjA8OptYjzqavDCk52Ah5uONTVhu Rhbik+hsmxtKqiRFGawB5xIUglolwP3FcAf9PmV43lU0sYtNHV1TUXofC2TXKJS7Gk KzDTAV21WK+/tWGVgMIQ1QdwhEPwx36nL29elboU= Date: Thu, 23 Jul 2020 21:15:27 -0700 From: Andrew Morton To: akpm@linux-foundation.org, cl@linux.com, guro@fb.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, shakeelb@google.com, songmuchun@bytedance.com, stable@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 07/15] mm: memcg/slab: fix memory leak at non-root kmem_cache destroy Message-ID: <20200724041527.cGFVoVytc%akpm@linux-foundation.org> In-Reply-To: <20200723211432.b31831a0df3bc2cbdae31b40@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: C71841004F864 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000229, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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); _