From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2BCD212880D for ; Thu, 1 Feb 2024 20:23:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706819008; cv=none; b=pvJ6U1EmeoS3tRZbW61nUjsXTqjvQ9czpwocV5PO5eM1B8jNTCc4Tr+7+7f59tpqOct7so1ok4w8nSj8lNvDkduf7gXw44a3KvyIPdO/KJrS1QOWOuJxEBO2HuNp0jC/W81TidChSHX0S0Depm3Szrr2YPh4GbGjN0BLJxveOmg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706819008; c=relaxed/simple; bh=Ul+NGisJHiIjILztE+udTNbfja29Xn6UZg3lAr3kDHs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fdmfby0Vwm535ikZpKvUvdEW1rUYdDxTRgFHETYNHmeU5bxdT8sr+ryFMSgVQnr69avTIYt08QpR0h12ylChAB5LxtZV5cnmy92D8xfb2wSwHR7f0cub3enuJ+++ffUsMlN8MFThHEybAWk2hdKdjSnwdIUxVuzJGwwEbk07SOU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=qQvSp7Ln; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qQvSp7Ln" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ls73UDXLTul69kZxFyEUzYQs+IXMDVS27If7g9tm5jc=; b=qQvSp7Ln+qaGIdJxaR9LI10OeP 6oou1d6bk/0uILyLl2LYkyoRg/3N2dPJNk49vrqLPDYmmsZUYT4Sw88zDj+uJQMaQ6WdWJBnxpKEc 9LELpQ7SGEPUwTrpEGoXFbfJtoA3BZTHpH1aKXmd5XU1MxxxyiqZNGlxjupaCztSwCLWnwU+DExj6 ST7YVH1azmB1elQdPv3I0z8SIf9gj3I4pLFKWiy+ZohAZM4kfhn6jL5Exfj250ljpUVEyJAIo6yEB NTDe/lxZ3r+hTJVL96uFvXBRq0z0D7Rl1L1eJvmI7z2jhKNbn18jWFujJGimspZNPKOOh9CJ3N9ys cs2OGBLA==; 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> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240129070934.3717659-5-wangkefeng.wang@huawei.com> 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!