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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30D2EC64EC4 for ; Mon, 6 Mar 2023 20:54:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229893AbjCFUyH (ORCPT ); Mon, 6 Mar 2023 15:54:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229907AbjCFUyE (ORCPT ); Mon, 6 Mar 2023 15:54:04 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F40739CEF for ; Mon, 6 Mar 2023 12:54:01 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id EDCF4B81126 for ; Mon, 6 Mar 2023 20:53:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9934FC433EF; Mon, 6 Mar 2023 20:53:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1678136038; bh=Jq2Cvb2QKEc6mlie9mspPfpqAkF2PbJvGFd20jbInGg=; h=Date:To:From:Subject:From; b=q4SMowgFg5SvSS/Ct7pAQxeYeRrwQk675b8pn/CBOCICkURNPdb3EWUM8BFHBFvg6 Pr8kE2Gmhbn4WxuC4BVZSdv8I0OlBJs1I2B5hMSUlrxDXQjgayKEp4crSvKqBqvK/U eYLMpF698d13gdKzGu7Cide0ZIZkJmHdreZliRY4= Date: Mon, 06 Mar 2023 12:53:57 -0800 To: mm-commits@vger.kernel.org, willy@infradead.org, tangyeechou@gmail.com, shakeelb@google.com, roman.gushchin@linux.dev, muchun.song@linux.dev, mhocko@suse.com, hannes@cmpxchg.org, findns94@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-memcg-prevent-memoryoom_control-load-store-tearing.patch added to mm-unstable branch Message-Id: <20230306205358.9934FC433EF@smtp.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: Prevent memory.oom_control load/store tearing has been added to the -mm mm-unstable branch. Its filename is mm-memcg-prevent-memoryoom_control-load-store-tearing.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memcg-prevent-memoryoom_control-load-store-tearing.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 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 via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Yue Zhao Subject: mm, memcg: Prevent memory.oom_control load/store tearing Date: Mon, 6 Mar 2023 23:41:37 +0800 The knob for cgroup v1 memory controller: memory.oom_control is not protected by any locking so it can be modified while it is used. This is not an actual problem because races are unlikely. But it is better to use READ_ONCE/WRITE_ONCE to prevent compiler from doing anything funky. The access of memcg->oom_kill_disable is lockless, so it can be concurrently set at the same time as we are trying to read it. Link: https://lkml.kernel.org/r/20230306154138.3775-4-findns94@gmail.com Signed-off-by: Yue Zhao Acked-by: Shakeel Butt Acked-by: Roman Gushchin Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Muchun Song Cc: Tang Yizhou Signed-off-by: Andrew Morton --- --- a/mm/memcontrol.c~mm-memcg-prevent-memoryoom_control-load-store-tearing +++ a/mm/memcontrol.c @@ -4515,7 +4515,7 @@ static int mem_cgroup_oom_control_read(s { struct mem_cgroup *memcg = mem_cgroup_from_seq(sf); - seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable); + seq_printf(sf, "oom_kill_disable %d\n", READ_ONCE(memcg->oom_kill_disable)); seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom); seq_printf(sf, "oom_kill %lu\n", atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL])); @@ -4531,7 +4531,7 @@ static int mem_cgroup_oom_control_write( if (mem_cgroup_is_root(memcg) || !((val == 0) || (val == 1))) return -EINVAL; - memcg->oom_kill_disable = val; + WRITE_ONCE(memcg->oom_kill_disable, val); if (!val) memcg_oom_recover(memcg); _ Patches currently in -mm which might be from findns94@gmail.com are mm-memcg-prevent-memoryoomgroup-load-store-tearing.patch mm-memcg-prevent-memoryswappiness-load-store-tearing.patch mm-memcg-prevent-memoryoom_control-load-store-tearing.patch mm-memcg-prevent-memorysoft_limit_in_bytes-load-store-tearing.patch