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 267FFC43331 for ; Thu, 2 Apr 2020 04:07:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DB84520747 for ; Thu, 2 Apr 2020 04:07:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bWi6kF3t" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB84520747 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 8D48D8E004D; Thu, 2 Apr 2020 00:07:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8833D8E000D; Thu, 2 Apr 2020 00:07:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 799608E004D; Thu, 2 Apr 2020 00:07:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0083.hostedemail.com [216.40.44.83]) by kanga.kvack.org (Postfix) with ESMTP id 663EE8E000D for ; Thu, 2 Apr 2020 00:07:29 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 2E2601277 for ; Thu, 2 Apr 2020 04:07:29 +0000 (UTC) X-FDA: 76661580618.04.wind88_415259eaac129 X-HE-Tag: wind88_415259eaac129 X-Filterd-Recvd-Size: 3834 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Apr 2020 04:07:28 +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 BC437206E9; Thu, 2 Apr 2020 04:07:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585800448; bh=EYnmskJjPgk1xOGcBYLlh3u8Ro9LSKRn7i8XkUKJo8k=; h=Date:From:To:Subject:In-Reply-To:From; b=bWi6kF3tNxoUpvQ54v/AVJLsq8wI+h5S1vIrZu1WeKQNLGLqHxt2pab60ZV5Tl8Ez 8MjzHwugoGsK7+qxAP5EisQl+SMAixyrINv2148yemrb/viyJV1JMolNTFjkVZwMTr 362X20+KRR9ZlXbgjxKlqptQWUAI8ZJl0ig96uPs= Date: Wed, 01 Apr 2020 21:07:27 -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 077/155] mm, memcg: prevent memory.min load/store tearing Message-ID: <20200402040727.hkXp15f5V%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.min load/store tearing This can be set concurrently with reads, which may cause the wrong value to be propagated. Link: http://lkml.kernel.org/r/e809b4e6b0c1626dac6945970de06409a180ee65.1584034301.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 | 5 +++-- mm/page_counter.c | 9 +++++---- 2 files changed, 8 insertions(+), 6 deletions(-) --- a/mm/memcontrol.c~mm-memcg-prevent-memorymin-load-store-tearing +++ a/mm/memcontrol.c @@ -6389,7 +6389,7 @@ enum mem_cgroup_protection mem_cgroup_pr return MEMCG_PROT_NONE; if (parent == root) { - memcg->memory.emin = memcg->memory.min; + memcg->memory.emin = READ_ONCE(memcg->memory.min); memcg->memory.elow = memcg->memory.low; goto out; } @@ -6397,7 +6397,8 @@ enum mem_cgroup_protection mem_cgroup_pr parent_usage = page_counter_read(&parent->memory); memcg->memory.emin = effective_protection(usage, parent_usage, - memcg->memory.min, READ_ONCE(parent->memory.emin), + READ_ONCE(memcg->memory.min), + READ_ONCE(parent->memory.emin), atomic_long_read(&parent->memory.children_min_usage)); memcg->memory.elow = effective_protection(usage, parent_usage, --- a/mm/page_counter.c~mm-memcg-prevent-memorymin-load-store-tearing +++ a/mm/page_counter.c @@ -17,14 +17,15 @@ static void propagate_protected_usage(st unsigned long usage) { unsigned long protected, old_protected; - unsigned long low; + unsigned long low, min; long delta; if (!c->parent) return; - if (c->min || atomic_long_read(&c->min_usage)) { - protected = min(usage, c->min); + min = READ_ONCE(c->min); + if (min || atomic_long_read(&c->min_usage)) { + protected = min(usage, min); old_protected = atomic_long_xchg(&c->min_usage, protected); delta = protected - old_protected; if (delta) @@ -207,7 +208,7 @@ void page_counter_set_min(struct page_co { struct page_counter *c; - counter->min = nr_pages; + WRITE_ONCE(counter->min, nr_pages); for (c = counter; c; c = c->parent) propagate_protected_usage(c, atomic_long_read(&c->usage)); _