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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 8EBC3C4320A for ; Wed, 25 Aug 2021 07:40:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7159F61214 for ; Wed, 25 Aug 2021 07:40:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235922AbhHYHlS (ORCPT ); Wed, 25 Aug 2021 03:41:18 -0400 Received: from verein.lst.de ([213.95.11.211]:55132 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231687AbhHYHlS (ORCPT ); Wed, 25 Aug 2021 03:41:18 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 2F4E067357; Wed, 25 Aug 2021 09:40:30 +0200 (CEST) Date: Wed, 25 Aug 2021 09:40:29 +0200 From: Christoph Hellwig To: Alex Sierra Cc: akpm@linux-foundation.org, Felix.Kuehling@amd.com, linux-mm@kvack.org, rcampbell@nvidia.com, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, hch@lst.de, jgg@nvidia.com, jglisse@redhat.com Subject: Re: [PATCH v1 03/14] mm: add iomem vma selection for memory migration Message-ID: <20210825074029.GC29433@lst.de> References: <20210825034828.12927-1-alex.sierra@amd.com> <20210825034828.12927-4-alex.sierra@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210825034828.12927-4-alex.sierra@amd.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Aug 24, 2021 at 10:48:17PM -0500, Alex Sierra wrote: > In this case, this is used to migrate pages from device memory, back to > system memory. This particular device memory type should be accessible > by the CPU, through IOMEM access. Typically, zone device public type > memory falls into this category. > > Signed-off-by: Alex Sierra > --- > include/linux/migrate.h | 1 + > mm/migrate.c | 3 ++- > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index 4bb4e519e3f5..6b16f417384f 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -156,6 +156,7 @@ static inline unsigned long migrate_pfn(unsigned long pfn) > enum migrate_vma_direction { > MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, > MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, > + MIGRATE_VMA_SELECT_IOMEM = 1 << 2, > }; > > struct migrate_vma { > diff --git a/mm/migrate.c b/mm/migrate.c > index e3a10e2a1bb3..d4ae2da99607 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -2406,7 +2406,8 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, > if (is_write_device_private_entry(entry)) > mpfn |= MIGRATE_PFN_WRITE; > } else { > - if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) > + if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM) && > + !(migrate->flags & MIGRATE_VMA_SELECT_IOMEM)) This makes the MIGRATE_VMA_SELECT_SYSTEM and MIGRATE_VMA_SELECT_IOMEM behave entirely identifical, that is redundant. I think we need to distinguish between the dfferent cases here. I think the right check would be pfn_valid(), which should be true for system memory, and false for iomem. Also shouldn't this be called DEVICE_PUBLIC instead of IOMEM?