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 0521DC77B60 for ; Tue, 28 Mar 2023 23:22:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229724AbjC1XWN (ORCPT ); Tue, 28 Mar 2023 19:22:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229942AbjC1XVy (ORCPT ); Tue, 28 Mar 2023 19:21:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80F1D358E for ; Tue, 28 Mar 2023 16:21:48 -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 1C6B8619A3 for ; Tue, 28 Mar 2023 23:21:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7182FC433EF; Tue, 28 Mar 2023 23:21:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1680045707; bh=y9l25tYHfOpMwPIEFZMKZHdLarxGU0UJnpxJ61Ml/iA=; h=Date:To:From:Subject:From; b=AZDM9yAoAePiq1aItofItnOMdYQHUsy/jqul1YbREyNx+78KNU0rRlHNcfyVz94Fi qR2Mas/12u11iqi/tAGYwpwFUhYskPzfZuTQuErU3Xehp0WnhS4jMliWLlOoNqgXnC 5FJnQsGomCiQvBrJIcCOcd3P6o1fN3tOMF5tsk98= Date: Tue, 28 Mar 2023 16:21:47 -0700 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: [merged mm-stable] mm-memcg-prevent-memoryoom_control-load-store-tearing.patch removed from -mm tree Message-Id: <20230328232147.7182FC433EF@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm, memcg: prevent memory.oom_control load/store tearing has been removed from the -mm tree. Its filename was mm-memcg-prevent-memoryoom_control-load-store-tearing.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ 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|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. All occurrences of memcg->oom_kill_disable are updated with [READ|WRITE]_ONCE. [findns94@gmail.com: v3] Link: https://lkml.kernel.org/r/20230308162555.14195-4-findns94@gmail.com Link: https://lkml.kernel.org/r/20230306154138.377-4-findns94@gmail.com Signed-off-by: Yue Zhao Acked-by: Shakeel Butt Acked-by: Roman Gushchin Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Muchun Song Cc: Tang Yizhou Signed-off-by: Andrew Morton --- mm/memcontrol.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/mm/memcontrol.c~mm-memcg-prevent-memoryoom_control-load-store-tearing +++ a/mm/memcontrol.c @@ -1929,7 +1929,7 @@ static bool mem_cgroup_oom(struct mem_cg * Please note that mem_cgroup_out_of_memory might fail to find a * victim and then we have to bail out from the charge path. */ - if (memcg->oom_kill_disable) { + if (READ_ONCE(memcg->oom_kill_disable)) { if (current->in_user_fault) { css_get(&memcg->css); current->memcg_in_oom = memcg; @@ -1999,7 +1999,7 @@ bool mem_cgroup_oom_synchronize(bool han if (locked) mem_cgroup_oom_notify(memcg); - if (locked && !memcg->oom_kill_disable) { + if (locked && !READ_ONCE(memcg->oom_kill_disable)) { mem_cgroup_unmark_under_oom(memcg); finish_wait(&memcg_oom_waitq, &owait.wait); mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask, @@ -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); @@ -5354,7 +5354,7 @@ mem_cgroup_css_alloc(struct cgroup_subsy page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX); if (parent) { WRITE_ONCE(memcg->swappiness, mem_cgroup_swappiness(parent)); - memcg->oom_kill_disable = parent->oom_kill_disable; + WRITE_ONCE(memcg->oom_kill_disable, READ_ONCE(parent->oom_kill_disable)); page_counter_init(&memcg->memory, &parent->memory); page_counter_init(&memcg->swap, &parent->swap); _ Patches currently in -mm which might be from findns94@gmail.com are