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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 396B6C43331 for ; Thu, 2 Apr 2020 04:07:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E525220747 for ; Thu, 2 Apr 2020 04:07:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="j0A7yDHK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E525220747 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 96F5F8E004E; Thu, 2 Apr 2020 00:07:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 947488E000D; Thu, 2 Apr 2020 00:07:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 884808E004E; Thu, 2 Apr 2020 00:07:32 -0400 (EDT) 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 6E4EB8E000D for ; Thu, 2 Apr 2020 00:07:32 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 42AC2180AD807 for ; Thu, 2 Apr 2020 04:07:32 +0000 (UTC) X-FDA: 76661580744.01.foot16_41c69e797e349 X-HE-Tag: foot16_41c69e797e349 X-Filterd-Recvd-Size: 3271 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Apr 2020 04:07:31 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E48D0206E9; Thu, 2 Apr 2020 04:07:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585800451; bh=uYXfR12CzljIyxo+icLLUEM/yF/4mdJhbUGpkfc6Jjk=; h=Date:From:To:Subject:In-Reply-To:From; b=j0A7yDHKFxs0+vqc/itjoSW2oAsoYNo7cK5J4WDTRX5dGPb8Ul44eOiseXnqS8Qf0 H4XjB10suEeo5aE+7S8MhY3yOwwf43c8FFxamPnxlu8h6rujz0qSgJBUT/Xqz0ytx1 wU0lbNQE6zI2guyJFF5UBYTnBatFQgkyMMCToOHI= Date: Wed, 01 Apr 2020 21:07:30 -0700 From: Andrew Morton To: akpm@linux-foundation.org, chris@chrisdown.name, guro@fb.com, hannes@cmpxchg.org, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, tj@kernel.org, torvalds@linux-foundation.org Subject: [patch 078/155] mm, memcg: prevent memory.swap.max load tearing Message-ID: <20200402040730.jK4QNPwaV%akpm@linux-foundation.org> In-Reply-To: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: Chris Down Subject: mm, memcg: prevent memory.swap.max load tearing The write side of this is xchg()/smp_mb(), so that's all good. Just a few sites missing a READ_ONCE. Link: http://lkml.kernel.org/r/bbec2c3d822217334855c8877a9d28b2a6d395fb.1584034301.git.chris@chrisdown.name Signed-off-by: Chris Down Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Roman Gushchin Cc: Tejun Heo Signed-off-by: Andrew Morton --- mm/memcontrol.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/memcontrol.c~mm-memcg-prevent-memoryswapmax-load-tearing +++ a/mm/memcontrol.c @@ -1525,7 +1525,7 @@ void mem_cgroup_print_oom_meminfo(struct if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->swap)), - K((u64)memcg->swap.max), memcg->swap.failcnt); + K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt); else { pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->memsw)), @@ -1558,7 +1558,7 @@ unsigned long mem_cgroup_get_max(struct unsigned long swap_max; memsw_max = memcg->memsw.max; - swap_max = memcg->swap.max; + swap_max = READ_ONCE(memcg->swap.max); swap_max = min(swap_max, (unsigned long)total_swap_pages); max = min(max + swap_max, memsw_max); } @@ -7117,7 +7117,8 @@ bool mem_cgroup_swap_full(struct page *p return false; for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) - if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.max) + if (page_counter_read(&memcg->swap) * 2 >= + READ_ONCE(memcg->swap.max)) return true; return false; _