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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 82EC6C433E0 for ; Thu, 28 Jan 2021 10:00:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 31DA164DBD for ; Thu, 28 Jan 2021 10:00:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232071AbhA1KAC (ORCPT ); Thu, 28 Jan 2021 05:00:02 -0500 Received: from mx2.suse.de ([195.135.220.15]:60244 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231779AbhA1J74 (ORCPT ); Thu, 28 Jan 2021 04:59:56 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 58EA1AC97; Thu, 28 Jan 2021 09:59:14 +0000 (UTC) Date: Thu, 28 Jan 2021 10:59:06 +0100 From: Oscar Salvador To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Thomas Gleixner , "Peter Zijlstra (Intel)" , Mike Rapoport , Michal Hocko , Wei Yang Subject: Re: [PATCH v1 1/2] mm/cma: expose all pages to the buddy if activation of an area fails Message-ID: <20210128095906.GA5250@localhost.localdomain> References: <20210127101813.6370-1-david@redhat.com> <20210127101813.6370-2-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210127101813.6370-2-david@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 27, 2021 at 11:18:12AM +0100, David Hildenbrand wrote: > Right now, if activation fails, we might already have exposed some pages to > the buddy for CMA use (although they will never get actually used by CMA), > and some pages won't be exposed to the buddy at all. > > Let's check for "single zone" early and on error, don't expose any pages > for CMA use - instead, expose them to the buddy available for any use. > Simply call free_reserved_page() on every single page - easier than > going via free_reserved_area(), converting back and forth between pfns > and virt addresses. > > In addition, make sure to fixup totalcma_pages properly. > > Example: 6 GiB QEMU VM with "... hugetlb_cma=2G movablecore=20% ...": > [ 0.006891] hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node > [ 0.006893] cma: Reserved 2048 MiB at 0x0000000100000000 > [ 0.006893] hugetlb_cma: reserved 2048 MiB on node 0 > ... > [ 0.175433] cma: CMA area hugetlb0 could not be activated > > Before this patch: > # cat /proc/meminfo > MemTotal: 5867348 kB > MemFree: 5692808 kB > MemAvailable: 5542516 kB > ... > CmaTotal: 2097152 kB > CmaFree: 1884160 kB > > After this patch: > # cat /proc/meminfo > MemTotal: 6077308 kB > MemFree: 5904208 kB > MemAvailable: 5747968 kB > ... > CmaTotal: 0 kB > CmaFree: 0 kB > > Note: cma_init_reserved_mem() makes sure that we always cover full > pageblocks / MAX_ORDER - 1 pages. > > Cc: Andrew Morton > Cc: Thomas Gleixner > Cc: "Peter Zijlstra (Intel)" > Cc: Mike Rapoport > Cc: Oscar Salvador > Cc: Michal Hocko > Cc: Wei Yang > Signed-off-by: David Hildenbrand Besides benefit of the error handling, I find this code much more cleaer: Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE L3