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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEC89C6FA82 for ; Tue, 13 Sep 2022 11:23:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 851D58D0001; Tue, 13 Sep 2022 07:23:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 801936B0073; Tue, 13 Sep 2022 07:23:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6C9C68D0001; Tue, 13 Sep 2022 07:23:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 5C9666B0072 for ; Tue, 13 Sep 2022 07:23:31 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 25E281211D2 for ; Tue, 13 Sep 2022 11:23:31 +0000 (UTC) X-FDA: 79906826622.06.4807DCE Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf25.hostedemail.com (Postfix) with ESMTP id A79AAA00C2 for ; Tue, 13 Sep 2022 11:23:30 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6CB961063; Tue, 13 Sep 2022 04:23:36 -0700 (PDT) Received: from [10.163.58.193] (unknown [10.163.58.193]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A89F93F71A; Tue, 13 Sep 2022 04:23:27 -0700 (PDT) Message-ID: <7dccfd5d-7fa1-440e-91a2-8aa35b9d968b@arm.com> Date: Tue, 13 Sep 2022 16:53:24 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 01/16] mm/page_alloc: ensure kswapd doesn't accidentally go to sleep Content-Language: en-US To: Matthew Wilcox Cc: Miaohe Lin , akpm@linux-foundation.org, david@redhat.com, osalvador@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220909092451.24883-1-linmiaohe@huawei.com> <20220909092451.24883-2-linmiaohe@huawei.com> From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=none; spf=pass (imf25.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663068210; a=rsa-sha256; cv=none; b=I06CF0BBXH+e4fqDEyBk3ixcQjbKwOr1Tc9wZG7goJpwbnqk1WebXoi8/IlZ+EqAtcVCLT AvgTii7hczIW5DlJbgb+4B5V/3Nsn7KIf/BY/Pwuw7AyvRql02yyzEpUQa3i9XXvgXVfHw 8YsbxAZWcN4uS5g9XDRs9kCTQMKXels= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663068210; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=B/XQs/i4f7vI19fSo/aLE7foLqilXPjfxmGQHZwzncg=; b=NbjzmViatpDUVC8lsMA1STReChdfXpUZEkwsxtEc7zzO2DtPVhYLzaSLgfEldFvEjwkkPd T1q7t1L7p7LGEyIrypjz20Q33DxUCCmNymBYEHftTju7e4HzS1ZC9pCEMB2bEwTNU58EPz 6EBc8Gmo3WwusqZ3JneqO8TvFTc066A= Authentication-Results: imf25.hostedemail.com; dkim=none; spf=pass (imf25.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com; dmarc=pass (policy=none) header.from=arm.com X-Rspam-User: X-Rspamd-Queue-Id: A79AAA00C2 X-Rspamd-Server: rspam04 X-Stat-Signature: n81kbkkea9iesg3rqxdi3u749e4am3t9 X-HE-Tag: 1663068210-156526 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: On 9/13/22 13:28, Matthew Wilcox wrote: > On Tue, Sep 13, 2022 at 12:32:50PM +0530, Anshuman Khandual wrote: >> >> On 9/9/22 14:54, Miaohe Lin wrote: >>> If ALLOC_KSWAPD is set, wake_all_kswapds() will be called to ensure >>> kswapd doesn't accidentally go to sleep. But when reserve_flags is >>> set, alloc_flags will be overwritten and ALLOC_KSWAPD is thus lost. >>> Preserve the ALLOC_KSWAPD flag in alloc_flags to ensure kswapd won't >>> go to sleep accidentally. >> Currently wake_all_kswapds() gets skipped subsequently if ALLOC_KSWAPD >> is lost, but this only happens when the 'retry:' loops is taken ? > Right, but see the comment: > > /* Ensure kswapd doesn't accidentally go to sleep as long as we loop */ > > and that is not currently true. I think that was an inadvertent change. > Particularly since the changelog for 0a79cdad5eb2 says "No functional > change". Got it, thanks for the explanation.