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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 85199C47247 for ; Fri, 8 May 2020 14:16:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 29A7A207DD for ; Fri, 8 May 2020 14:16:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="Dj8/u6gZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 29A7A207DD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9B5F3900002; Fri, 8 May 2020 10:16:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 965B88E0003; Fri, 8 May 2020 10:16:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 854D6900002; Fri, 8 May 2020 10:16:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0203.hostedemail.com [216.40.44.203]) by kanga.kvack.org (Postfix) with ESMTP id 6E2528E0003 for ; Fri, 8 May 2020 10:16:35 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 2EA97181AC9CB for ; Fri, 8 May 2020 14:16:35 +0000 (UTC) X-FDA: 76793752350.02.stew80_395d196caa455 X-HE-Tag: stew80_395d196caa455 X-Filterd-Recvd-Size: 4169 Received: from forwardcorp1p.mail.yandex.net (forwardcorp1p.mail.yandex.net [77.88.29.217]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Fri, 8 May 2020 14:16:34 +0000 (UTC) Received: from mxbackcorp2j.mail.yandex.net (mxbackcorp2j.mail.yandex.net [IPv6:2a02:6b8:0:1619::119]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id 9C6732E0997; Fri, 8 May 2020 17:16:31 +0300 (MSK) Received: from myt5-70c90f7d6d7d.qloud-c.yandex.net (myt5-70c90f7d6d7d.qloud-c.yandex.net [2a02:6b8:c12:3e2c:0:640:70c9:f7d]) by mxbackcorp2j.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id DzB0dpFFbi-GTXSjfvG; Fri, 08 May 2020 17:16:31 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1588947391; bh=Kz8084Qd+ukMFtBduY70Wrn/hOXrye0GrRmcB96gXCQ=; h=Message-ID:Date:To:From:Subject:Cc; b=Dj8/u6gZYmMA/f3gA/Gqiy6C2yfCTKO//L+zyCsxYhibDXK2RnLGgmSAlaRXqqzlw Tq4x4ndeaEZyJGVAZxWLr/JJnElxICKB49ARgoON0n79PGht6cp9Htyk3J3iszXQle cbNDkAqPk/3XuNtXYZDXX5+C1gTBipR7wPmNTtdg= Authentication-Results: mxbackcorp2j.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-vpn.dhcp.yndx.net (dynamic-vpn.dhcp.yndx.net [2a02:6b8:b080:7008::1:4]) by myt5-70c90f7d6d7d.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id tvHw4hmnaj-GTWWnWM4; Fri, 08 May 2020 17:16:29 +0300 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client certificate not present) Subject: [PATCH] doc: cgroup: update note about conditions when oom killer is invoked From: Konstantin Khlebnikov To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton Cc: cgroups@vger.kernel.org, Roman Gushchin , Michal Hocko Date: Fri, 08 May 2020 17:16:29 +0300 Message-ID: <158894738928.208854.5244393925922074518.stgit@buzz> User-Agent: StGit/0.22-32-g6a05 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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: Starting from v4.19 commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the charge path") cgroup oom killer is no longer invoked only from page faults. Now it implements the same semantics as global OOM killer: allocation context invokes OOM killer and keeps retrying until success. Signed-off-by: Konstantin Khlebnikov --- Documentation/admin-guide/cgroup-v2.rst | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index bcc80269bb6a..1bb9a8f6ebe1 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1172,6 +1172,13 @@ PAGE_SIZE multiple when read back. Under certain circumstances, the usage may go over the limit temporarily. + In default configuration regular 0-order allocation always + succeed unless OOM killer choose current task as a victim. + + Some kinds of allocations don't invoke the OOM killer. + Caller could retry them differently, return into userspace + as -ENOMEM or silently ignore in cases like disk readahead. + This is the ultimate protection mechanism. As long as the high limit is used and monitored properly, this limit's utility is limited to providing the final safety net. @@ -1228,17 +1235,9 @@ PAGE_SIZE multiple when read back. The number of time the cgroup's memory usage was reached the limit and allocation was about to fail. - Depending on context result could be invocation of OOM - killer and retrying allocation or failing allocation. - - Failed allocation in its turn could be returned into - userspace as -ENOMEM or silently ignored in cases like - disk readahead. For now OOM in memory cgroup kills - tasks iff shortage has happened inside page fault. - This event is not raised if the OOM killer is not considered as an option, e.g. for failed high-order - allocations. + allocations or if caller asked to not retry attempts. oom_kill The number of processes belonging to this cgroup