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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT 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 3C29BC2BCA1 for ; Fri, 7 Jun 2019 15:49:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CF1821479 for ; Fri, 7 Jun 2019 15:49:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559922545; bh=qkNXViCj49Ut9Bq05gvEuHF57ravamNBtcJkC5IfgdU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tpjJEwBGuxb4cgDRvKDQRKXq3EffL6uVbaGPG8iiuRyINqZ6PGvQj8/tNGXzrgXMn roTl2p9FSpaZ3UWarW0G7qpX7o/V6e9TuVJ0QN+0UL1y4wjNZ97PtCr+9ah4dBw9mJ WtgS70jaRePHKj3TJCT3AlxWKwUegLhWybeceKAY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731887AbfFGPtE (ORCPT ); Fri, 7 Jun 2019 11:49:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:34596 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731869AbfFGPtA (ORCPT ); Fri, 7 Jun 2019 11:49:00 -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 6613820657; Fri, 7 Jun 2019 15:48:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559922539; bh=qkNXViCj49Ut9Bq05gvEuHF57ravamNBtcJkC5IfgdU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rZNOQJNamgRc5IHZ/6wbGM4h6y8oH3cQmopWTyoJfZjFsvrPJG3XRecykU3nViYQB uqW6rThY0Lz4DQuO3JspgmKPPe9YKK1Pwt8Kq58z9JNb/GkrbB7VcAzSaPxP1GPleA w0qp67fZSu2/qyUvIrPRo+EW6KKTP89DB6thgna0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiri Slaby , Michal Hocko , Vladimir Davydov , Shakeel Butt , Johannes Weiner , Raghavendra K T , Andrew Morton , Linus Torvalds Subject: [PATCH 5.1 49/85] memcg: make it work on sparse non-0-node systems Date: Fri, 7 Jun 2019 17:39:34 +0200 Message-Id: <20190607153855.009533841@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190607153849.101321647@linuxfoundation.org> References: <20190607153849.101321647@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jiri Slaby commit 3e8589963773a5c23e2f1fe4bcad0e9a90b7f471 upstream. We have a single node system with node 0 disabled: Scanning NUMA topology in Northbridge 24 Number of physical nodes 2 Skipping disabled node 0 Node 1 MemBase 0000000000000000 Limit 00000000fbff0000 NODE_DATA(1) allocated [mem 0xfbfda000-0xfbfeffff] This causes crashes in memcg when system boots: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 #PF error: [normal kernel read fault] ... RIP: 0010:list_lru_add+0x94/0x170 ... Call Trace: d_lru_add+0x44/0x50 dput.part.34+0xfc/0x110 __fput+0x108/0x230 task_work_run+0x9f/0xc0 exit_to_usermode_loop+0xf5/0x100 It is reproducible as far as 4.12. I did not try older kernels. You have to have a new enough systemd, e.g. 241 (the reason is unknown -- was not investigated). Cannot be reproduced with systemd 234. The system crashes because the size of lru array is never updated in memcg_update_all_list_lrus and the reads are past the zero-sized array, causing dereferences of random memory. The root cause are list_lru_memcg_aware checks in the list_lru code. The test in list_lru_memcg_aware is broken: it assumes node 0 is always present, but it is not true on some systems as can be seen above. So fix this by avoiding checks on node 0. Remember the memcg-awareness by a bool flag in struct list_lru. Link: http://lkml.kernel.org/r/20190522091940.3615-1-jslaby@suse.cz Fixes: 60d3fd32a7a9 ("list_lru: introduce per-memcg lists") Signed-off-by: Jiri Slaby Acked-by: Michal Hocko Suggested-by: Vladimir Davydov Acked-by: Vladimir Davydov Reviewed-by: Shakeel Butt Cc: Johannes Weiner Cc: Raghavendra K T Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/list_lru.h | 1 + mm/list_lru.c | 8 +++----- 2 files changed, 4 insertions(+), 5 deletions(-) --- a/include/linux/list_lru.h +++ b/include/linux/list_lru.h @@ -54,6 +54,7 @@ struct list_lru { #ifdef CONFIG_MEMCG_KMEM struct list_head list; int shrinker_id; + bool memcg_aware; #endif }; --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -37,11 +37,7 @@ static int lru_shrinker_id(struct list_l static inline bool list_lru_memcg_aware(struct list_lru *lru) { - /* - * This needs node 0 to be always present, even - * in the systems supporting sparse numa ids. - */ - return !!lru->node[0].memcg_lrus; + return lru->memcg_aware; } static inline struct list_lru_one * @@ -451,6 +447,8 @@ static int memcg_init_list_lru(struct li { int i; + lru->memcg_aware = memcg_aware; + if (!memcg_aware) return 0;