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Content-Language: en-US To: Zi Yan , David Hildenbrand , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Michael Ellerman , Christoph Hellwig , Marek Szyprowski , Robin Murphy , linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org References: <20211115193725.737539-1-zi.yan@sent.com> From: Vlastimil Babka In-Reply-To: <20211115193725.737539-1-zi.yan@sent.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 41E9AB000180 Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=Rj0Bb7aN; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=37Ndmb7m; dmarc=none; spf=pass (imf25.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Stat-Signature: cx7m5hmw4ftcggmhho86ra4ajzsdma63 X-HE-Tag: 1637325185-316881 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 11/15/21 20:37, Zi Yan wrote: > From: Zi Yan > > Hi David, > > You suggested to make alloc_contig_range() deal with pageblock_order instead of > MAX_ORDER - 1 and get rid of MAX_ORDER - 1 dependency in virtio_mem[1]. This > patchset is my attempt to achieve that. Please take a look and let me know if > I am doing it correctly or not. > > From what my understanding, cma required alignment of > max(MAX_ORDER - 1, pageblock_order), because when MIGRATE_CMA was introduced, > __free_one_page() does not prevent merging two different pageblocks, when > MAX_ORDER - 1 > pageblock_order. But current __free_one_page() implementation > does prevent that. But it does prevent that only for isolated pageblock, not CMA, and yout patchset doesn't seem to expand that to CMA? Or am I missing something. > It should be OK to just align cma to pageblock_order. > alloc_contig_range() relies on MIGRATE_CMA to get free pages, so it can use > pageblock_order as alignment too. > > In terms of virtio_mem, if I understand correctly, it relies on > alloc_contig_range() to obtain contiguous free pages and offlines them to reduce > guest memory size. As the result of alloc_contig_range() alignment change, > virtio_mem should be able to just align PFNs to pageblock_order. > > Thanks. > > > [1] https://lore.kernel.org/linux-mm/28b57903-fae6-47ac-7e1b-a1dd41421349@redhat.com/ > > Zi Yan (3): > mm: cma: alloc_contig_range: use pageblock_order as the single > alignment. > drivers: virtio_mem: use pageblock size as the minimum virtio_mem > size. > arch: powerpc: adjust fadump alignment to be pageblock aligned. > > arch/powerpc/include/asm/fadump-internal.h | 4 +--- > drivers/virtio/virtio_mem.c | 6 ++---- > include/linux/mmzone.h | 5 +---- > kernel/dma/contiguous.c | 2 +- > mm/cma.c | 6 ++---- > mm/page_alloc.c | 12 +++++------- > 6 files changed, 12 insertions(+), 23 deletions(-) >