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 A3428C433FE for ; Sun, 24 Apr 2022 20:34:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239580AbiDXUhJ (ORCPT ); Sun, 24 Apr 2022 16:37:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239581AbiDXUhF (ORCPT ); Sun, 24 Apr 2022 16:37:05 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62E6D156E2E for ; Sun, 24 Apr 2022 13:34:04 -0700 (PDT) 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 dfw.source.kernel.org (Postfix) with ESMTPS id F406F612B4 for ; Sun, 24 Apr 2022 20:34:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55EDEC385A7; Sun, 24 Apr 2022 20:34:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1650832443; bh=cma6a7LfRraO8A3Ds5GeRRuej5damAJ4ZsKlhtMJE4s=; h=Date:To:From:Subject:From; b=YwGAbjYfCixu3DqXLc9m8TJNi1wZITyBeVSX1kYOfjaV1wcBMrUXmBztzASj+93yL /iCbnYe3lw82O+E09WwOR309wkaZZhi64WZXN7UXmgiNRxzW4Zu4SiTAXolcjaH48T Gq17IDjkgBp1oW7s6liqv8DvRyi4lIB+iNw9jjOc= Date: Sun, 24 Apr 2022 13:34:02 -0700 To: mm-commits@vger.kernel.org, tj@kernel.org, shakeelb@google.com, roman.gushchin@linux.dev, mhocko@kernel.org, hannes@cmpxchg.org, void@manifault.com, akpm@linux-foundation.org From: Andrew Morton Subject: + cgroup-fix-racy-check-in-alloc_pagecache_max_30m-helper-function.patch added to -mm tree Message-Id: <20220424203403.55EDEC385A7@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: cgroup: fix racy check in alloc_pagecache_max_30M() helper function has been added to the -mm tree. Its filename is cgroup-fix-racy-check-in-alloc_pagecache_max_30m-helper-function.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/cgroup-fix-racy-check-in-alloc_pagecache_max_30m-helper-function.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/cgroup-fix-racy-check-in-alloc_pagecache_max_30m-helper-function.patch 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 and is updated there every 3-4 working days ------------------------------------------------------ From: David Vernet Subject: cgroup: fix racy check in alloc_pagecache_max_30M() helper function alloc_pagecache_max_30M() in the cgroup memcg tests performs a 50MB pagecache allocation, which it expects to be capped at 30MB due to the calling process having a memory.high setting of 30MB. After the allocation, the function contains a check that verifies that MB(29) < memory.current <= MB(30). This check can actually fail non-deterministically. The testcases that use this function are test_memcg_high() and test_memcg_max(), which set memory.min and memory.max to 30MB respectively for the cgroup under test. The allocation can slightly exceed this number in both cases, and for memory.max, the process performing the allocation will not have the OOM killer invoked as it's performing a pagecache allocation. This patchset therefore updates the above check to instead use the verify_close() helper function. Link: https://lkml.kernel.org/r/20220423155619.3669555-6-void@manifault.com Signed-off-by: David Vernet Acked-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Shakeel Butt Cc: Tejun Heo Signed-off-by: Andrew Morton --- tools/testing/selftests/cgroup/test_memcontrol.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/tools/testing/selftests/cgroup/test_memcontrol.c~cgroup-fix-racy-check-in-alloc_pagecache_max_30m-helper-function +++ a/tools/testing/selftests/cgroup/test_memcontrol.c @@ -568,9 +568,14 @@ static int alloc_pagecache_max_30M(const { size_t size = MB(50); int ret = -1; - long current; + long current, high, max; int fd; + high = cg_read_long(cgroup, "memory.high"); + max = cg_read_long(cgroup, "memory.max"); + if (high != MB(30) && max != MB(30)) + goto cleanup; + fd = get_temp_fd(); if (fd < 0) return -1; @@ -579,7 +584,7 @@ static int alloc_pagecache_max_30M(const goto cleanup; current = cg_read_long(cgroup, "memory.current"); - if (current <= MB(29) || current > MB(30)) + if (!values_close(current, MB(30), 5)) goto cleanup; ret = 0; _ Patches currently in -mm which might be from void@manifault.com are cgroups-refactor-children-cgroups-in-memcg-tests.patch cgroup-account-for-memory_recursiveprot-in-test_memcg_low.patch cgroup-account-for-memory_localevents-in-test_memcg_oom_group_leaf_events.patch cgroup-removing-racy-check-in-test_memcg_sock.patch cgroup-fix-racy-check-in-alloc_pagecache_max_30m-helper-function.patch