From patchwork Tue Oct 29 00:54:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shakeel Butt X-Patchwork-Id: 11216839 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 57ECA112C for ; Tue, 29 Oct 2019 00:54:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1337821479 for ; Tue, 29 Oct 2019 00:54:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="VNIhRIVz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1337821479 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2FE7B6B0005; Mon, 28 Oct 2019 20:54:29 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 2AE856B0006; Mon, 28 Oct 2019 20:54:29 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1C5556B0007; Mon, 28 Oct 2019 20:54:29 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0127.hostedemail.com [216.40.44.127]) by kanga.kvack.org (Postfix) with ESMTP id E87FA6B0005 for ; Mon, 28 Oct 2019 20:54:28 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 8B56D52C3 for ; Tue, 29 Oct 2019 00:54:28 +0000 (UTC) X-FDA: 76095001416.01.hair90_442065c15d242 X-Spam-Summary: 50,3,0,d7aa96b042b1a375,d41d8cd98f00b204,3w423xqgkclaixqauubrweewbu.secbydkn-ccalqsa.ehw@flex--shakeelb.bounces.google.com,:guro@fb.com:hannes@cmpxchg.org:mhocko@kernel.org:akpm@linux-foundation.org::cgroups@vger.kernel.org:linux-kernel@vger.kernel.org:shakeelb@google.com:edumazet@google.com:gthelen@google.com:syzbot+13f93c99c06988391efe@syzkaller.appspotmail.com,RULES_HIT:41:152:355:379:541:800:960:966:973:988:989:1260:1277:1313:1314:1345:1437:1516:1518:1535:1542:1593:1594:1711:1730:1747:1777:1792:2196:2198:2199:2200:2393:2496:2559:2562:3138:3139:3140:3141:3142:3152:3352:3865:3866:3867:3868:3870:4321:4385:5007:6261:6653:7903:9969:10004:10400:10450:10455:11026:11658:11914:12043:12048:12114:12294:12296:12297:12438:12555:12679:12895:12986:13153:13221:13228:13229:14096:14097:14104:14181:14394:14659:14721:19904:19999:21080:21444:21451:21627:30054,0,RBL:209.85.160.202:@flex--shakeelb.bounces.google.com:.lbl8.mailshell.net-62.18.0.100 66.100.201.100,CacheIP:none,Bay esian:0. X-HE-Tag: hair90_442065c15d242 X-Filterd-Recvd-Size: 5205 Received: from mail-qt1-f202.google.com (mail-qt1-f202.google.com [209.85.160.202]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Oct 2019 00:54:28 +0000 (UTC) Received: by mail-qt1-f202.google.com with SMTP id y10so12777947qti.1 for ; Mon, 28 Oct 2019 17:54:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=CJNyfCkSt7mazdpKxm+NauccC7aNCXbzHO2WmG+WXZI=; b=VNIhRIVznNTE4231t1PB9Y892IckjdElWezZZVpfEZj80/mzanDBafaCAPwbWdo/2+ A2IlnsRAL2Blt3IvIwX0ISb+ZmFwG9yrBZ55rX1/xuj9NUAqSD3FHneUmyprKlV5yl3q tTlgF3TG2RXMaFaXAlfpSDe9OiAODZDJ/pnsUOZfcjt++CXArvZZTjQ5fY2m5Jz4KDJj UImudqlau9RYfYGT+aEy1/m9RTwJwhjIFgij71FJyZX0avIJ5/L6Yy34dJ5ovk87MzOg vpUccTmI91a3yMxtIvMawk0rByNgb7F2mUfDUfz6Bqs+0lifTZdjCcjDQGftK7LTeiXB t6Tw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=CJNyfCkSt7mazdpKxm+NauccC7aNCXbzHO2WmG+WXZI=; b=CH5FlQfghFIHGFkoOhdeYuBt/R0LUBIaOh6S2lQhQIz8AeOEquMRwqBbSWmzhx7axW yNix+/OdJMdrTGwAHefN48+DypJofF9lCOXsoZ1HwrluSBdfFKrQOhAIhcsZxBsK4V/+ gWSsvhQXvJ43LfS8vfuh7Z4lLA4g02hORV5szZrdMYpEHt6PBdYjav+j2ptwZRHL57XV 1xbhrITO+SMLtQ8zbk3Mu/Csr+cXhlyV0tBcv1uZQ0HGK2CR89Mu8BE0tTMdC+qQAUwE lJlpMFRfotpEJCFhKVXik3a+z7v93pUjt6/vQQlnGkUvZiYEIFOS6HyqClBqJpf2Qpcm QYYg== X-Gm-Message-State: APjAAAXKU+m3tocR7GgZQhIGnzDgOn1XkcMxpsf+d0kB0M7qY5TqMs9F Jr1+kjahpw+IommRZcYA3uY3ifgzlmEVXQ== X-Google-Smtp-Source: APXvYqyuC1vSPb0iXXoyj+RX6tq0hHQYQPJSlVZL8/Xu5SdTk1tHt39Bxai/8EbXawqb+7npXxeAku+T+G4lIw== X-Received: by 2002:a37:9d15:: with SMTP id g21mr4415148qke.71.1572310467233; Mon, 28 Oct 2019 17:54:27 -0700 (PDT) Date: Mon, 28 Oct 2019 17:54:05 -0700 Message-Id: <20191029005405.201986-1-shakeelb@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH] mm: memcontrol: fix data race in mem_cgroup_select_victim_node From: Shakeel Butt To: Roman Gushchin , Johannes Weiner , Michal Hocko , Andrew Morton Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Shakeel Butt , Eric Dumazet , Greg Thelen , syzbot+13f93c99c06988391efe@syzkaller.appspotmail.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: Syzbot reported the following bug: BUG: KCSAN: data-race in mem_cgroup_select_victim_node / mem_cgroup_select_victim_node write to 0xffff88809fade9b0 of 4 bytes by task 8603 on cpu 0: mem_cgroup_select_victim_node+0xb5/0x3d0 mm/memcontrol.c:1686 try_to_free_mem_cgroup_pages+0x175/0x4c0 mm/vmscan.c:3376 reclaim_high.constprop.0+0xf7/0x140 mm/memcontrol.c:2349 mem_cgroup_handle_over_high+0x96/0x180 mm/memcontrol.c:2430 tracehook_notify_resume include/linux/tracehook.h:197 [inline] exit_to_usermode_loop+0x20c/0x2c0 arch/x86/entry/common.c:163 prepare_exit_to_usermode+0x180/0x1a0 arch/x86/entry/common.c:194 swapgs_restore_regs_and_return_to_usermode+0x0/0x40 read to 0xffff88809fade9b0 of 4 bytes by task 7290 on cpu 1: mem_cgroup_select_victim_node+0x92/0x3d0 mm/memcontrol.c:1675 try_to_free_mem_cgroup_pages+0x175/0x4c0 mm/vmscan.c:3376 reclaim_high.constprop.0+0xf7/0x140 mm/memcontrol.c:2349 mem_cgroup_handle_over_high+0x96/0x180 mm/memcontrol.c:2430 tracehook_notify_resume include/linux/tracehook.h:197 [inline] exit_to_usermode_loop+0x20c/0x2c0 arch/x86/entry/common.c:163 prepare_exit_to_usermode+0x180/0x1a0 arch/x86/entry/common.c:194 swapgs_restore_regs_and_return_to_usermode+0x0/0x40 mem_cgroup_select_victim_node() can be called concurrently which reads and modifies memcg->last_scanned_node without any synchrnonization. So, read and modify memcg->last_scanned_node with READ_ONCE()/WRITE_ONCE() to stop potential reordering. Signed-off-by: Shakeel Butt Suggested-by: Eric Dumazet Cc: Greg Thelen Reported-by: syzbot+13f93c99c06988391efe@syzkaller.appspotmail.com --- mm/memcontrol.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c4c555055a72..5a06739dd3e4 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1667,7 +1667,7 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) int node; mem_cgroup_may_update_nodemask(memcg); - node = memcg->last_scanned_node; + node = READ_ONCE(memcg->last_scanned_node); node = next_node_in(node, memcg->scan_nodes); /* @@ -1678,7 +1678,7 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) if (unlikely(node == MAX_NUMNODES)) node = numa_node_id(); - memcg->last_scanned_node = node; + WRITE_ONCE(memcg->last_scanned_node, node); return node; } #else