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=-2.5 required=3.0 tests=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 CC33DECE587 for ; Mon, 14 Oct 2019 13:00:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8F3DC20673 for ; Mon, 14 Oct 2019 13:00:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F3DC20673 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3938F8E0006; Mon, 14 Oct 2019 09:00:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 320E28E0001; Mon, 14 Oct 2019 09:00:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 20BD88E0006; Mon, 14 Oct 2019 09:00:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id F25FF8E0001 for ; Mon, 14 Oct 2019 09:00:27 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 631865DF0 for ; Mon, 14 Oct 2019 13:00:27 +0000 (UTC) X-FDA: 76042398894.14.lead14_3ec50d885730 X-HE-Tag: lead14_3ec50d885730 X-Filterd-Recvd-Size: 4238 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Mon, 14 Oct 2019 13:00:26 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0AD0FB87C; Mon, 14 Oct 2019 13:00:25 +0000 (UTC) Date: Mon, 14 Oct 2019 15:00:23 +0200 From: Michal Hocko To: Anshuman Khandual Cc: akpm@linux-foundation.org, ard.biesheuvel@linaro.org, broonie@kernel.org, christophe.leroy@c-s.fr, dan.j.williams@intel.com, dave.hansen@intel.com, davem@davemloft.net, gerald.schaefer@de.ibm.com, gregkh@linuxfoundation.org, heiko.carstens@de.ibm.com, jgg@ziepe.ca, jhogan@kernel.org, keescook@chromium.org, kirill@shutemov.name, linux@armlinux.org.uk, mark.rutland@arm.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, mpe@ellerman.id.au, paul.burton@mips.com, paulus@samba.org, penguin-kernel@i-love.sakura.ne.jp, peterz@infradead.org, ralf@linux-mips.org, rppt@linux.vnet.ibm.com, schowdary@nvidia.com, schwidefsky@de.ibm.com, Steven.Price@arm.com, tglx@linutronix.de, vbabka@suse.cz, vgupta@synopsys.com, willy@infradead.org, yamada.masahiro@socionext.com, linux-mm@kvack.org Subject: Re: + mm-hugetlb-make-alloc_gigantic_page-available-for-general-use.patch added to -mm tree Message-ID: <20191014130023.GF317@dhcp22.suse.cz> References: <20191011202932.GZoUOoURm%akpm@linux-foundation.org> <20191014121730.GE317@dhcp22.suse.cz> <89f328f0-ca00-a9b0-8df6-808a53bfcdd4@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <89f328f0-ca00-a9b0-8df6-808a53bfcdd4@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Mon 14-10-19 18:23:00, Anshuman Khandual wrote: > > > On 10/14/2019 05:47 PM, Michal Hocko wrote: > > On Fri 11-10-19 13:29:32, Andrew Morton wrote: > >> alloc_gigantic_page() implements an allocation method where it scans over > >> various zones looking for a large contiguous memory block which could not > >> have been allocated through the buddy allocator. A subsequent patch which > >> tests arch page table helpers needs such a method to allocate PUD_SIZE > >> sized memory block. In the future such methods might have other use cases > >> as well. So alloc_gigantic_page() has been split carving out actual > >> memory allocation method and made available via new > >> alloc_gigantic_page_order(). > > > > You are exporting a helper used for hugetlb internally. Is this really > > Right, because the helper i.e alloc_gigantic_page() is generic enough which > scans over various zones to allocate a page order which could not be allocated > through the buddy. Only thing which is HugeTLB specific in there, is struct > hstate from where the order is derived with huge_page_order(). Otherwise it > is very generic. > > > what is needed? I haven't followed this patchset but don't you simply > > Originally I had just implemented similar allocator inside the test itself > but then figured that alloc_gigantic_page() can be factored out to create > a generic enough allocator helper. > > > need a generic 1GB allocator? If yes then you should be looking at > > The test needs a PUD_SIZE allocator. > > > alloc_contig_range. > > IIUC alloc_contig_range() requires (start pfn, end pfn) for the region to be > allocated. But before that all applicable zones need to be scanned to figure > out any available and suitable pfn range for alloc_contig_range() to try. In > this case pfn_range_valid_gigantic() check seemed reasonable while scanning > the zones. > > If pfn_range_valid_gigantic() is good enough or could be made more generic, > then the new factored alloc_gigantic_page_order() could be made a helper in > mm/page_alloc.c OK, thanks for the clarification. This all means that this patch is not the right approach. If you need a more generic alloc_contig_range then add it to page_alloc.c and make it completely independent on the hugetlb config and the code. Hugetlb allocator can reuse that helper. -- Michal Hocko SUSE Labs