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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 F2C89C64E8A for ; Mon, 30 Nov 2020 13:23:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7AF3B206F9 for ; Mon, 30 Nov 2020 13:23:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="RW6digj3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7AF3B206F9 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B79ED8D0006; Mon, 30 Nov 2020 08:23:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B28FB8D0001; Mon, 30 Nov 2020 08:23:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A3F6B8D0006; Mon, 30 Nov 2020 08:23:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0007.hostedemail.com [216.40.44.7]) by kanga.kvack.org (Postfix) with ESMTP id 8D70C8D0001 for ; Mon, 30 Nov 2020 08:23:49 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 4C0E78249980 for ; Mon, 30 Nov 2020 13:23:49 +0000 (UTC) X-FDA: 77541152178.22.fruit74_2805ce1273a2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 27B3B18038E87 for ; Mon, 30 Nov 2020 13:23:49 +0000 (UTC) X-HE-Tag: fruit74_2805ce1273a2 X-Filterd-Recvd-Size: 3925 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Mon, 30 Nov 2020 13:23:48 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1606742627; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TN6v/OxH2OCtpqDqCR+fNEKl5rFIXLW24KeSiZIJqiY=; b=RW6digj3PddxPw8W2vUmwPfX8SzTgA6ZQWwm9a1rvExLhiwTyCWILAl7bYZK2AX7y2pt6m IQWh8cOAapkpMr3xBVHD4QDFBzygXraCpsg+nrxzGr3kPVNV1f4OSH04kZHBLxGUC1zRoN 2n2yYDl6nW0HwaVcneleQRL3f0Sa1SY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 62D52AD19; Mon, 30 Nov 2020 13:23:47 +0000 (UTC) Date: Mon, 30 Nov 2020 14:23:45 +0100 From: Michal Hocko To: Muchun Song Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, guro@fb.com, sfr@canb.auug.org.au, alex.shi@linux.alibaba.com, alexander.h.duyck@linux.intel.com, laoar.shao@gmail.com, richard.weiyang@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/memcg: fix NULL pointer dereference at workingset_eviction Message-ID: <20201130132345.GJ17338@dhcp22.suse.cz> References: <20201130131512.6043-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201130131512.6043-1-songmuchun@bytedance.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon 30-11-20 21:15:12, Muchun Song wrote: > We found a case of kernel panic. The stack trace is as follows > (omit some irrelevant information): > > BUG: kernel NULL pointer dereference, address: 00000000000000c8 > RIP: 0010:workingset_eviction+0x26b/0x450 > Call Trace: > __remove_mapping+0x224/0x2b0 > shrink_page_list+0x8c2/0x14e0 > shrink_inactive_list+0x1bf/0x3f0 > ? do_raw_spin_unlock+0x49/0xc0 > ? _raw_spin_unlock+0xa/0x20 > shrink_lruvec+0x401/0x640 > > This was caused by commit 76761ffa9ea1 ("mm/memcg: bail out early when > !memcg in mem_cgroup_lruvec"). When the parameter of memcg is NULL, we > should not use the &pgdat->__lruvec. So this just reverts commit > 76761ffa9ea1 to fix it. > > Fixes: 76761ffa9ea1 ("mm/memcg: bail out early when !memcg in mem_cgroup_lruvec") I do not see any commits like that in the current Linus tree. Is this a commit id from the linux-next? If yes, can we just fold it into the respective patch in mmotm tree please? > Signed-off-by: Muchun Song > --- > include/linux/memcontrol.h | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index f9a496c4eac7..a1416205507c 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -610,17 +610,20 @@ mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid) > static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg, > struct pglist_data *pgdat) > { > + struct mem_cgroup_per_node *mz; > struct lruvec *lruvec; > > - if (mem_cgroup_disabled() || !memcg) { > + if (mem_cgroup_disabled()) { > lruvec = &pgdat->__lruvec; > - } else { > - struct mem_cgroup_per_node *mz; > - > - mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id); > - lruvec = &mz->lruvec; > + goto out; > } > > + if (!memcg) > + memcg = root_mem_cgroup; > + > + mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id); > + lruvec = &mz->lruvec; > +out: > /* > * Since a node can be onlined after the mem_cgroup was created, > * we have to be prepared to initialize lruvec->pgdat here; > -- > 2.11.0 > -- Michal Hocko SUSE Labs