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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rVdag-0000000GjJx-3Ppq; Thu, 01 Feb 2024 20:23:18 +0000 Date: Thu, 1 Feb 2024 20:23:18 +0000 From: Matthew Wilcox To: Kefeng Wang Cc: Andrew Morton , linux-mm@kvack.org, Tony Luck , Naoya Horiguchi , Miaohe Lin , David Hildenbrand , Muchun Song , Benjamin LaHaise , jglisse@redhat.com, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH rfc 4/9] mm: remove MIGRATE_SYNC_NO_COPY mode Message-ID: References: <20240129070934.3717659-1-wangkefeng.wang@huawei.com> <20240129070934.3717659-5-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240129070934.3717659-5-wangkefeng.wang@huawei.com> X-Rspamd-Queue-Id: 34641A0007 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: w97cm8ai7ifepp9nsp4uftef1wgw7r66 X-HE-Tag: 1706819000-520279 X-HE-Meta: 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 xqIO0T5s qMqt89K+GbIdUv563QwNWyUaanBm9+FFEY8qNjwIWGbNCeXS8es+hg+ReKomJzhOKcu6QH3iho3UsutKXUq1688TJf1cdK/y3561BqW7xL34FgmmEkPu2A0UpUvOVicqoop31lNjOkt93y1Z7lc2mli/sTEOONh7/S/n7S8UAZQpd1LrDHpfFN6gAlw== 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: List-Subscribe: List-Unsubscribe: On Mon, Jan 29, 2024 at 03:09:29PM +0800, Kefeng Wang wrote: > Commit 2916ecc0f9d4 ("mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY") > introduce a new MIGRATE_SYNC_NO_COPY mode to allow to offload the copy to > a device DMA engine, which is only used __migrate_device_pages() to decide > whether or not copy the old page, and the MIGRATE_SYNC_NO_COPY mode only > set in hmm, as the MIGRATE_SYNC_NO_COPY set is removed by previous cleanup, > it seems that we could remove the unnecessary MIGRATE_SYNC_NO_COPY. Ah! I didn't understand the point of what you were doing in the previous patch. Now it makes a lot more sense. This is a big improvement, thanks!