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=-0.7 required=3.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 E5EB3C433ED for ; Fri, 21 May 2021 09:37:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3A11660FEF for ; Fri, 21 May 2021 09:37:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A11660FEF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sina.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 57F076B012B; Fri, 21 May 2021 05:37:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 52E756B012C; Fri, 21 May 2021 05:37:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3CEA96B012D; Fri, 21 May 2021 05:37:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0096.hostedemail.com [216.40.44.96]) by kanga.kvack.org (Postfix) with ESMTP id 091326B012B for ; Fri, 21 May 2021 05:37:29 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 9C54C907F for ; Fri, 21 May 2021 09:37:29 +0000 (UTC) X-FDA: 78164735418.03.98AF33D Received: from r3-21.sinamail.sina.com.cn (r3-21.sinamail.sina.com.cn [202.108.3.21]) by imf28.hostedemail.com (Postfix) with SMTP id 41EA920007E0 for ; Fri, 21 May 2021 09:37:23 +0000 (UTC) Received: from unknown (HELO localhost.localdomain)([221.199.207.229]) by sina.com (172.16.97.32) with ESMTP id 60A77F51000235E4; Fri, 21 May 2021 17:37:23 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com X-SMAIL-MID: 611910629110 From: Hillf Danton To: Marco Elver Cc: akpm@linux-foundation.org, glider@google.com, dvyukov@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, Mel Gorman , stable@vger.kernel.org Subject: Re: [PATCH] kfence: use TASK_IDLE when awaiting allocation Date: Fri, 21 May 2021 17:37:15 +0800 Message-Id: <20210521093715.1813-1-hdanton@sina.com> In-Reply-To: <20210521083209.3740269-1-elver@google.com> References: <20210521083209.3740269-1-elver@google.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 41EA920007E0 Authentication-Results: imf28.hostedemail.com; dkim=none; spf=pass (imf28.hostedemail.com: domain of hdanton@sina.com designates 202.108.3.21 as permitted sender) smtp.mailfrom=hdanton@sina.com; dmarc=none X-Rspamd-Server: rspam03 X-Stat-Signature: sjkn9obhs4bd96ddd46kqstm1h6wjfbw X-HE-Tag: 1621589843-388009 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.004364, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 21 May 2021 10:32:09 +0200 Marco Elver wrote: >Since wait_event() uses TASK_UNINTERRUPTIBLE by default, waiting for an >allocation counts towards load. However, for KFENCE, this does not make >any sense, since there is no busy work we're awaiting. Because of a blocking wq callback, kfence_timer should be queued on a unbound workqueue in the first place. Feel free to add a followup to replace system_power_efficient_wq with system_unbound_wq if it makes sense to you that kfence behaves as correctly as expected independent of CONFIG_WQ_POWER_EFFICIENT_DEFAULT given "system_power_efficient_wq is identical to system_wq if 'wq_power_efficient' is disabled."