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 ADE93C43331 for ; Thu, 2 Apr 2020 04:07:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 73B3E206E9 for ; Thu, 2 Apr 2020 04:07:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="TJqhbEnq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 73B3E206E9 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 1F6B78E004A; Thu, 2 Apr 2020 00:07:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1A65B8E000D; Thu, 2 Apr 2020 00:07:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0BC5E8E004A; Thu, 2 Apr 2020 00:07:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0170.hostedemail.com [216.40.44.170]) by kanga.kvack.org (Postfix) with ESMTP id EA3788E000D for ; Thu, 2 Apr 2020 00:07:19 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id A72C8824934B for ; Thu, 2 Apr 2020 04:07:19 +0000 (UTC) X-FDA: 76661580198.17.pull07_3fee78920b75a X-HE-Tag: pull07_3fee78920b75a X-Filterd-Recvd-Size: 4305 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Apr 2020 04:07:19 +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 24A2220747; Thu, 2 Apr 2020 04:07:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585800438; bh=0r/CtELKd0dP9nfG4sAFIibBnuHn7fI1V33VM2zcHV8=; h=Date:From:To:Subject:In-Reply-To:From; b=TJqhbEnqZWDQeG1FYYCLRH3tGjwhjlpgAmRNodr3LCMKoRX4HdlfRbisVk9I1T08P zt5rVJ5ZmlEWqaiKP5YdjrXcbwAmdzHCvZL0h2A2XytAJgBlB3i2oUD8EZkpIouAhq enTidQ/UD3OkK5jag49VAAPxo0cRKAbc1vCERHsM= Date: Wed, 01 Apr 2020 21:07:17 -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 074/155] mm, memcg: prevent memory.high load/store tearing Message-ID: <20200402040717.j_tcNT_CB%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.high load/store tearing A mem_cgroup's high attribute can be concurrently set at the same time as we are trying to read it -- for example, if we are in memory_high_write at the same time as we are trying to do high reclaim. Link: http://lkml.kernel.org/r/2f66f7038ed1d4688e59de72b627ae0ea52efa83.1584034301.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 | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/mm/memcontrol.c~mm-memcg-prevent-memoryhigh-load-store-tearing +++ a/mm/memcontrol.c @@ -2242,7 +2242,7 @@ static void reclaim_high(struct mem_cgro gfp_t gfp_mask) { do { - if (page_counter_read(&memcg->memory) <= memcg->high) + if (page_counter_read(&memcg->memory) <= READ_ONCE(memcg->high)) continue; memcg_memory_event(memcg, MEMCG_HIGH); try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true); @@ -2582,7 +2582,7 @@ done_restock: * reclaim, the cost of mismatch is negligible. */ do { - if (page_counter_read(&memcg->memory) > memcg->high) { + if (page_counter_read(&memcg->memory) > READ_ONCE(memcg->high)) { /* Don't bother a random interrupted task */ if (in_interrupt()) { schedule_work(&memcg->high_work); @@ -4325,7 +4325,8 @@ void mem_cgroup_wb_stats(struct bdi_writ *pheadroom = PAGE_COUNTER_MAX; while ((parent = parent_mem_cgroup(memcg))) { - unsigned long ceiling = min(memcg->memory.max, memcg->high); + unsigned long ceiling = min(memcg->memory.max, + READ_ONCE(memcg->high)); unsigned long used = page_counter_read(&memcg->memory); *pheadroom = min(*pheadroom, ceiling - min(ceiling, used)); @@ -5047,7 +5048,7 @@ mem_cgroup_css_alloc(struct cgroup_subsy if (!memcg) return ERR_PTR(error); - memcg->high = PAGE_COUNTER_MAX; + WRITE_ONCE(memcg->high, PAGE_COUNTER_MAX); memcg->soft_limit = PAGE_COUNTER_MAX; if (parent) { memcg->swappiness = mem_cgroup_swappiness(parent); @@ -5200,7 +5201,7 @@ static void mem_cgroup_css_reset(struct page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX); page_counter_set_min(&memcg->memory, 0); page_counter_set_low(&memcg->memory, 0); - memcg->high = PAGE_COUNTER_MAX; + WRITE_ONCE(memcg->high, PAGE_COUNTER_MAX); memcg->soft_limit = PAGE_COUNTER_MAX; memcg_wb_domain_size_changed(memcg); } @@ -6016,7 +6017,7 @@ static ssize_t memory_high_write(struct if (err) return err; - memcg->high = high; + WRITE_ONCE(memcg->high, high); for (;;) { unsigned long nr_pages = page_counter_read(&memcg->memory); _