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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 55AC4CA9EBA for ; Tue, 22 Oct 2019 20:15:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2570021783 for ; Tue, 22 Oct 2019 20:15:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="KaaLg/bw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389355AbfJVUPX (ORCPT ); Tue, 22 Oct 2019 16:15:23 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:34914 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389342AbfJVUPV (ORCPT ); Tue, 22 Oct 2019 16:15:21 -0400 Received: by mail-qt1-f196.google.com with SMTP id m15so28843992qtq.2 for ; Tue, 22 Oct 2019 13:15:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=SKH3PcY5YzXD6Qge68ymWg6Ins6ocLR9l5DfPryEBgk=; b=KaaLg/bw88z77buICYAJEe5iw5ThIZJCDvLL4q2RSdmGOXSdlsryIy4UAPdKiR3U1i TnF8jNwIgRKrMzBMH2cBT8Qyy9tg/M9wTtR3Wrx6e/JrVGOp77QhbBjRArE2l/meQdby SOdO/mGWcTubS8kR90ln5IenSVxDk0WPTvDqpdaDO4iRAPQXIssKgsKkCTzxFI7D99tI K/w9BneoewwmdaDHDt5q8QWenhYLUUAhYRi0GJm58lfdROEHZrbuhSNsUmJ7vhrTLZoB TlgRns9OFeILnr1C45VJ/hBfpRmLpXl6WY6/23dwwSlktV02dZHRpDlk39xE/9wyzzJf OKPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=SKH3PcY5YzXD6Qge68ymWg6Ins6ocLR9l5DfPryEBgk=; b=njth46QfQn7vl2AAzuC2CF1x8+E+T/tgREx++/f1vO2qqsaXgf6plBYvuIwrtyze64 rozNH0LBedwXjVmc4FN14ov5Jflkc9QkBvsLQIhLx4WZnlbU0u7ATE0udsAQvE0Yc+SM uBGtjaTEvJSY1Dj4j/OCDtwiI7f/vN6/UMVzwaCswoIcA3s6pS/iBE4GIYtsHfBsdHo6 j6iMlF/rYIgavh+uwiouNbyzYJbq+3cTr0J6Dz/VYBSKxYIPvv7J/bzM8MlG5jsDH+fE M/Jn+fPbbt8KhTZTPZbOlmGLviNm8p743XOBunOcqh9myYTFQQ4mK+lEyUP/Qvg++4W5 xmiQ== X-Gm-Message-State: APjAAAVHTPc9x8kamLX5elVtrm5ThigxU2huVfPwTdoScWSounEgpehS 1Q+02f9hZIZnjhfWoKtLCXxuvg== X-Google-Smtp-Source: APXvYqwgUaBUtrSrtIlAxyDVz2P4+gAp3Nwe5EnwHYyjxxj2PszLHekWjQXPyQk3tbOPUN9yPnbdVQ== X-Received: by 2002:a0c:d0e1:: with SMTP id b30mr5126174qvh.197.1571775320721; Tue, 22 Oct 2019 13:15:20 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::3:869e]) by smtp.gmail.com with ESMTPSA id e15sm7759814qkm.130.2019.10.22.13.15.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Oct 2019 13:15:20 -0700 (PDT) From: Johannes Weiner To: Andrew Morton Cc: Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 2/2] mm: memcontrol: try harder to set a new memory.high Date: Tue, 22 Oct 2019 16:15:18 -0400 Message-Id: <20191022201518.341216-2-hannes@cmpxchg.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191022201518.341216-1-hannes@cmpxchg.org> References: <20191022201518.341216-1-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Setting a memory.high limit below the usage makes almost no effort to shrink the cgroup to the new target size. While memory.high is a "soft" limit that isn't supposed to cause OOM situations, we should still try harder to meet a user request through persistent reclaim. For example, after setting a 10M memory.high on an 800M cgroup full of file cache, the usage shrinks to about 350M: + cat /cgroup/workingset/memory.current 841568256 + echo 10M + cat /cgroup/workingset/memory.current 355729408 This isn't exactly what the user would expect to happen. Setting the value a few more times eventually whittles the usage down to what we are asking for: + echo 10M + cat /cgroup/workingset/memory.current 104181760 + echo 10M + cat /cgroup/workingset/memory.current 31801344 + echo 10M + cat /cgroup/workingset/memory.current 10440704 To improve this, add reclaim retry loops to the memory.high write() callback, similar to what we do for memory.max, to make a reasonable effort that the usage meets the requested size after the call returns. Afterwards, a single write() to memory.high is enough in all but extreme cases: + cat /cgroup/workingset/memory.current 841609216 + echo 10M + cat /cgroup/workingset/memory.current 10182656 Signed-off-by: Johannes Weiner --- mm/memcontrol.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ff90d4e7df37..8090b4c99ac7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6074,7 +6074,8 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); - unsigned long nr_pages; + unsigned int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; + bool drained = false; unsigned long high; int err; @@ -6085,12 +6086,29 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, memcg->high = high; - nr_pages = page_counter_read(&memcg->memory); - if (nr_pages > high) - try_to_free_mem_cgroup_pages(memcg, nr_pages - high, - GFP_KERNEL, true); + for (;;) { + unsigned long nr_pages = page_counter_read(&memcg->memory); + unsigned long reclaimed; + + if (nr_pages <= high) + break; + + if (signal_pending(current)) + break; + + if (!drained) { + drain_all_stock(memcg); + drained = true; + continue; + } + + reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high, + GFP_KERNEL, true); + + if (!reclaimed && !nr_retries--) + break; + } - memcg_wb_domain_size_changed(memcg); return nbytes; } -- 2.23.0