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 E9128C6FD18 for ; Tue, 28 Mar 2023 23:22:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229826AbjC1XWP (ORCPT ); Tue, 28 Mar 2023 19:22:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229901AbjC1XWD (ORCPT ); Tue, 28 Mar 2023 19:22:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67CD63593 for ; Tue, 28 Mar 2023 16:21:50 -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 01E23619A3 for ; Tue, 28 Mar 2023 23:21:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C77FC4339B; Tue, 28 Mar 2023 23:21:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1680045709; bh=QnJvQk3IBWQP8ulhxneL7i3bBqOpDFN1lUqRRoSz7IM=; h=Date:To:From:Subject:From; b=t9RrD0/VoaPz+Yu1Yq3GMg62x6WFZ4l1qVzqVXLd0yvb899fJPDYq+niJIfg91sOH YtI6W3xO2uwEEIcRU5dWR9LstwkWV/7NuNsjhQLoMCkwjEXppO+bWHoqps0ACMh7k7 YPc4olvzwazJ1uP4D8CdbeEnF83kuU3+606xfBOs= Date: Tue, 28 Mar 2023 16:21:48 -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-memorysoft_limit_in_bytes-load-store-tearing.patch removed from -mm tree Message-Id: <20230328232149.5C77FC4339B@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.soft_limit_in_bytes load/store tearing has been removed from the -mm tree. Its filename was mm-memcg-prevent-memorysoft_limit_in_bytes-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.soft_limit_in_bytes load/store tearing Date: Mon, 6 Mar 2023 23:41:38 +0800 The knob for cgroup v1 memory controller: memory.soft_limit_in_bytes 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->soft_limit is lockless, so it can be concurrently set at the same time as we are trying to read it. All occurrences of memcg->soft_limit are updated with [READ|WRITE]_ONCE. [findns94@gmail.com: v3] Link: https://lkml.kernel.org/r/20230308162555.14195-5-findns94@gmail.com Link: https://lkml.kernel.org/r/20230306154138.3775-5-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 | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/mm/memcontrol.c~mm-memcg-prevent-memorysoft_limit_in_bytes-load-store-tearing +++ a/mm/memcontrol.c @@ -3728,7 +3728,7 @@ static u64 mem_cgroup_read_u64(struct cg case RES_FAILCNT: return counter->failcnt; case RES_SOFT_LIMIT: - return (u64)memcg->soft_limit * PAGE_SIZE; + return (u64)READ_ONCE(memcg->soft_limit) * PAGE_SIZE; default: BUG(); } @@ -3870,7 +3870,7 @@ static ssize_t mem_cgroup_write(struct k if (IS_ENABLED(CONFIG_PREEMPT_RT)) { ret = -EOPNOTSUPP; } else { - memcg->soft_limit = nr_pages; + WRITE_ONCE(memcg->soft_limit, nr_pages); ret = 0; } break; @@ -5347,7 +5347,7 @@ mem_cgroup_css_alloc(struct cgroup_subsy return ERR_CAST(memcg); page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX); - memcg->soft_limit = PAGE_COUNTER_MAX; + WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX); #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP) memcg->zswap_max = PAGE_COUNTER_MAX; #endif @@ -5502,7 +5502,7 @@ static void mem_cgroup_css_reset(struct page_counter_set_min(&memcg->memory, 0); page_counter_set_low(&memcg->memory, 0); page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX); - memcg->soft_limit = PAGE_COUNTER_MAX; + WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX); page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX); memcg_wb_domain_size_changed(memcg); } _ Patches currently in -mm which might be from findns94@gmail.com are