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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 D8155CA9EB7 for ; Tue, 22 Oct 2019 20:15:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 94F182184C for ; Tue, 22 Oct 2019 20:15:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="KaaLg/bw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 94F182184C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=cmpxchg.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B6DD06B0006; Tue, 22 Oct 2019 16:15:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AF8236B0007; Tue, 22 Oct 2019 16:15:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 924D56B0008; Tue, 22 Oct 2019 16:15:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0104.hostedemail.com [216.40.44.104]) by kanga.kvack.org (Postfix) with ESMTP id 64B4B6B0006 for ; Tue, 22 Oct 2019 16:15:22 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id C2E5F7582 for ; Tue, 22 Oct 2019 20:15:21 +0000 (UTC) X-FDA: 76072525242.10.robin02_2ec6923a3f33a X-HE-Tag: robin02_2ec6923a3f33a X-Filterd-Recvd-Size: 5723 Received: from mail-qt1-f193.google.com (mail-qt1-f193.google.com [209.85.160.193]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Tue, 22 Oct 2019 20:15:21 +0000 (UTC) Received: by mail-qt1-f193.google.com with SMTP id z22so8255795qtq.11 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=eBKKBj68ewHoFVq0TE688Nv9m3nODcqnhzzpK8P1jr/TOSBz3PPKWyK+p9XQvcMYYR 06H9Xbl2hLPsSLYje9aCVGRMf/cyDKyoTAYBbeltqnl54HM5iZLW/Bs/BEf9v8ffBcHE +vMvBOhakUzRVxQE5Df69XlOJhBdAosMN0zINRcbnFsWR8iuKN/7v/4iwM2l1IAR42G9 /4TFkHWTB8E8l7nVdjkI6p8zHFYKTl3fQPbcrOqPEwTSMqxfyjx2ioEebyZi9uiNYoMD RMO5fu1gK8/mpIYISrWFBzw0fXOT16aR9naSTBaHaDsmqzrlWG3eUrhOjcGVK7+wckL7 Bhnw== X-Gm-Message-State: APjAAAWmizNxPuVzZoxeNfjr6ac7OUsdYkNx7Ps5kX9qgVspknckW+uI XFkHZTVjJB97mBbVLTmgbWBrFA== 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: quoted-printable 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: 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 =3D mem_cgroup_from_css(of_css(of)); - unsigned long nr_pages; + unsigned int nr_retries =3D MEM_CGROUP_RECLAIM_RETRIES; + bool drained =3D false; unsigned long high; int err; =20 @@ -6085,12 +6086,29 @@ static ssize_t memory_high_write(struct kernfs_op= en_file *of, =20 memcg->high =3D high; =20 - nr_pages =3D 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 =3D page_counter_read(&memcg->memory); + unsigned long reclaimed; + + if (nr_pages <=3D high) + break; + + if (signal_pending(current)) + break; + + if (!drained) { + drain_all_stock(memcg); + drained =3D true; + continue; + } + + reclaimed =3D try_to_free_mem_cgroup_pages(memcg, nr_pages - high, + GFP_KERNEL, true); + + if (!reclaimed && !nr_retries--) + break; + } =20 - memcg_wb_domain_size_changed(memcg); return nbytes; } =20 --=20 2.23.0