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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 4B3E0C07E96 for ; Thu, 15 Jul 2021 08:36:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D68C861370 for ; Thu, 15 Jul 2021 08:36:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D68C861370 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F25648D00A4; Thu, 15 Jul 2021 04:36:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ED4158D0065; Thu, 15 Jul 2021 04:36:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D76598D00A4; Thu, 15 Jul 2021 04:36:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0153.hostedemail.com [216.40.44.153]) by kanga.kvack.org (Postfix) with ESMTP id AC5088D0065 for ; Thu, 15 Jul 2021 04:36:04 -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 8C56E17AB0 for ; Thu, 15 Jul 2021 08:36:03 +0000 (UTC) X-FDA: 78364164606.03.5FE2357 Received: from outbound-smtp24.blacknight.com (outbound-smtp24.blacknight.com [81.17.249.192]) by imf10.hostedemail.com (Postfix) with ESMTP id 37EDF6001E77 for ; Thu, 15 Jul 2021 08:36:02 +0000 (UTC) Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp24.blacknight.com (Postfix) with ESMTPS id 16790C2ADC for ; Thu, 15 Jul 2021 09:35:59 +0100 (IST) Received: (qmail 14109 invoked from network); 15 Jul 2021 08:35:58 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.17.255]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 15 Jul 2021 08:35:58 -0000 Date: Thu, 15 Jul 2021 09:35:57 +0100 From: Mel Gorman To: "Zhang, Qiang" Cc: Matthew Wilcox , Andrew Morton , "Uladzislau Rezki (Sony)" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] mm/page_alloc: avoid hard lockups in __alloc_pages_bulk() Message-ID: <20210715083557.GP3809@techsingularity.net> References: <20210710112929.232268-1-qiang.zhang@windriver.com> <20210710114613.0db3ac139a7b3102a6ca3ad4@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Authentication-Results: imf10.hostedemail.com; dkim=none; spf=pass (imf10.hostedemail.com: domain of mgorman@techsingularity.net designates 81.17.249.192 as permitted sender) smtp.mailfrom=mgorman@techsingularity.net; dmarc=none X-Rspamd-Server: rspam05 X-Stat-Signature: s8m81k1cxy6zr9spgg95unj88y1ds161 X-Rspamd-Queue-Id: 37EDF6001E77 X-HE-Tag: 1626338162-466902 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 Sat, Jul 10, 2021 at 10:57:53PM +0000, Zhang, Qiang wrote: > ________________________________ > ??????: Matthew Wilcox > ????????: ??????, ???? 11, 2021 05:10 > ??????: Andrew Morton > ????: Zhang, Qiang; mgorman@techsingularity.net; linux-mm@kvack.org; linux-kernel@vger.kernel.org > ????: Re: [PATCH] mm/page_alloc: avoid hard lockups in __alloc_pages_bulk() > > [Please note: This e-mail is from an EXTERNAL e-mail address] > > On Sat, Jul 10, 2021 at 11:46:13AM -0700, Andrew Morton wrote: > > On Sat, 10 Jul 2021 19:29:29 +0800 qiang.zhang@windriver.com wrote: > > > > > From: Zqiang > > > > > > The __alloc_pages_bulk() mainly used for batch allocation of > > > order-0 pages, in the case of holding pagesets.lock, if too > > > many pages are required, maybe trigger hard lockup watchdog. > > > > Ouch. Has this been observed in testing? If so, can you please share > > the kernel debug output from that event? > > >This should be fixed in the caller by asking for fewer pages. > >The NFS and vmalloc cases have already been fixed for this. > > The NFS and vmalloc cases haven been fixed?? > I don??t see if there is any information about that? > AFAIK, NFS simply doesn't ask for a large enough number of pages to be of concern. For vmalloc, it's somewhat theoritical that it can happen for anything other than a stress test but this exists https://lore.kernel.org/r/20210705170537.43060-1-urezki@gmail.com I had no objection to the patch but didn't feel strongly enough to say anything about it either given that it was triggered artifically. -- Mel Gorman SUSE Labs