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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 83BEDC433DB for ; Mon, 15 Feb 2021 19:39:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0977F64E27 for ; Mon, 15 Feb 2021 19:39:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0977F64E27 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 659A88D013A; Mon, 15 Feb 2021 14:39:19 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5E2A08D012C; Mon, 15 Feb 2021 14:39:19 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D17A8D013A; Mon, 15 Feb 2021 14:39:19 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 3442F8D012C for ; Mon, 15 Feb 2021 14:39:19 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id EA8A31827E90F for ; Mon, 15 Feb 2021 19:39:18 +0000 (UTC) X-FDA: 77821515996.24.236BDFB Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf08.hostedemail.com (Postfix) with ESMTP id B038F80192C7 for ; Mon, 15 Feb 2021 19:39:12 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1613417957; h=from:from:reply-to: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=Fx2cr07cmhwLgVLKoMIL0c93fXgTqa4GArm3bCqwx58=; b=gmTzrbK2+uwQ0IULYjwTpZT7v8vs5KhYk9UoGVvxF/J51TVevzHw+bL/LFKeTPWTkK4woE 93/CuIfpEbenm1Odqa3C2PLHH7jGrJ8I2jSce3cYUWBJh5fsXETgfRVFc2vaT9YnHGtX6W v/lZPWRPIyz1VR0+PmlB/NMWpRX2NUo= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C133DAD29; Mon, 15 Feb 2021 19:39:16 +0000 (UTC) Date: Mon, 15 Feb 2021 20:39:15 +0100 From: Michal Hocko To: Muchun Song Cc: Jonathan Corbet , Mike Kravetz , Thomas Gleixner , mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, Peter Zijlstra , viro@zeniv.linux.org.uk, Andrew Morton , paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, Randy Dunlap , oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, Mina Almasry , David Rientjes , Matthew Wilcox , Oscar Salvador , "Song Bao Hua (Barry Song)" , David Hildenbrand , HORIGUCHI =?utf-8?B?TkFPWUEo5aCA5Y+jIOebtOS5nyk=?= , Joao Martins , Xiongchun duan , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , linux-fsdevel Subject: Re: [External] Re: [PATCH v15 4/8] mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Stat-Signature: zdjmk1mus6so56msanzn7qcn8aryw3tm X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B038F80192C7 Received-SPF: none (suse.com>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1613417952-565035 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: On Tue 16-02-21 02:19:20, Muchun Song wrote: > On Tue, Feb 16, 2021 at 1:48 AM Muchun Song = wrote: > > > > On Tue, Feb 16, 2021 at 12:28 AM Michal Hocko wrote= : > > > > > > On Mon 15-02-21 23:36:49, Muchun Song wrote: > > > [...] > > > > > There shouldn't be any real reason why the memory allocation fo= r > > > > > vmemmaps, or handling vmemmap in general, has to be done from w= ithin the > > > > > hugetlb lock and therefore requiring a non-sleeping semantic. A= ll that > > > > > can be deferred to a more relaxed context. If you want to make = a > > > > > > > > Yeah, you are right. We can put the freeing hugetlb routine to a > > > > workqueue. Just like I do in the previous version (before v13) pa= tch. > > > > I will pick up these patches. > > > > > > I haven't seen your v13 and I will unlikely have time to revisit th= at > > > version. I just wanted to point out that the actual allocation does= n't > > > have to happen from under the spinlock. There are multiple ways to = go > > > around that. Dropping the lock would be one of them. Preallocation > > > before the spin lock is taken is another. WQ is certainly an option= but > > > I would take it as the last resort when other paths are not feasibl= e. > > > > > > > "Dropping the lock" and "Preallocation before the spin lock" can limi= t > > the context of put_page to non-atomic context. I am not sure if there > > is a page puted somewhere under an atomic context. e.g. compaction. > > I am not an expert on this. >=20 > Using GFP_KERNEL will also use the current task cpuset to allocate > memory. Do we have an interface to ignore current task cpuset=EF=BC=9FI= f not, > WQ may be the only option and it also will not limit the context of > put_page. Right? Well, GFP_KERNEL is constrained to the task cpuset only if the said cpuset is hardwalled IIRC. But I do not see why this is a problem. --=20 Michal Hocko SUSE Labs