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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA7CEC04A68 for ; Thu, 28 Jul 2022 14:18:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C1D378E0001; Thu, 28 Jul 2022 10:18:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BCCF26B0073; Thu, 28 Jul 2022 10:18:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ABCC78E0001; Thu, 28 Jul 2022 10:18:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 9D1C36B0072 for ; Thu, 28 Jul 2022 10:18:26 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 68702140F89 for ; Thu, 28 Jul 2022 14:18:26 +0000 (UTC) X-FDA: 79736713812.01.8616822 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf02.hostedemail.com (Postfix) with ESMTP id B00428008A for ; Thu, 28 Jul 2022 14:18:23 +0000 (UTC) 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=6yJFmCjq7j3EiYzdT5riiMxTlawWcPIvBh3hMXTowos=; b=tDxZoPKAWg0/dgNc8WPgDxg/GU Cqip0gnoyz6wHT16FW+cISsYnciiRhJQJoGBhyEmDgr10vWdGHxQXgbeDwINuXO1kbuYeC/sjZeP2 YL5Bpzb4pLuVMHRMIHWGx6dbCQi7z1ISYzcN47FWNn18S3/wfhc0CFZHU9ceHq/TicqjYXSfKnnCt I0DHO+icFRZdgyIVmdT2GTmVVBn7V03KFoXARG+dX9D58LufJWqhEowXnKE+LUR4DRG9po0cLJxOp TYaxF9dYUmUynkBu2lr+XSm3QjPMO+x2rTqUDBoj57SfwUhRSelbReS+MITKMnHaLp4cre6i304W5 NZ9iEqTw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oH4Kx-003toI-8v; Thu, 28 Jul 2022 14:18:03 +0000 Date: Thu, 28 Jul 2022 15:18:03 +0100 From: Matthew Wilcox To: Jan Kara Cc: Christoph Hellwig , Bob Peterson , Andreas Gruenbacher , "Darrick J. Wong" , Damien Le Moal , Naohiro Aota , Johannes Thumshirn , cluster-devel@redhat.com, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Mel Gorman Subject: Re: remove iomap_writepage v2 Message-ID: References: <20220719041311.709250-1-hch@lst.de> <20220728111016.uwbaywprzkzne7ib@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220728111016.uwbaywprzkzne7ib@quack3> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659017906; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6yJFmCjq7j3EiYzdT5riiMxTlawWcPIvBh3hMXTowos=; b=ZowIUR5bzPCv209KcF7BYI4Aw4VMc15Vt1wozz8tkX8gY+idAEaHA67boH82uJItgBtFnp AYNOKI/4gsMxo5oEJ9sZXYoL6dKi3n3iHrLQc1XK8PhTtD+5xTM5zTsXlNSgm7zzYClMvU 01Gh0NIgRpkTvMDIINWHdiHcRMgVIOE= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=tDxZoPKA; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659017906; a=rsa-sha256; cv=none; b=8CO5aptlLQ6GxQ4Sjrs0EYaa4oNAOnBe12KYIawFnGgQ3FVSle1appb3pC4WhB0gGaSnc+ E6alEzPPQYr5BJRg66Rj/G6N31r/j7n06e+X98tSRNh5wBxW65l2MI8JjeVfedhuavrAwH 9wMwTPlGPzVTYr6hIhuHd+Ooj9DUiq4= X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: B00428008A X-Rspam-User: Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=tDxZoPKA; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Stat-Signature: f55mzge5dzwg8paedeqonb5mkrbse8ux X-HE-Tag: 1659017903-238823 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 Thu, Jul 28, 2022 at 01:10:16PM +0200, Jan Kara wrote: > Hi Christoph! > > On Tue 19-07-22 06:13:07, Christoph Hellwig wrote: > > this series removes iomap_writepage and it's callers, following what xfs > > has been doing for a long time. > > So this effectively means "no writeback from page reclaim for these > filesystems" AFAICT (page migration of dirty pages seems to be handled by > iomap_migrate_page()) which is going to make life somewhat harder for > memory reclaim when memory pressure is high enough that dirty pages are > reaching end of the LRU list. I don't expect this to be a problem on big > machines but it could have some undesirable effects for small ones > (embedded, small VMs). I agree per-page writeback has been a bad idea for > efficiency reasons for at least last 10-15 years and most filesystems > stopped dealing with more complex situations (like block allocation) from > ->writepage() already quite a few years ago without any bug reports AFAIK. > So it all seems like a sensible idea from FS POV but are MM people on board > or at least aware of this movement in the fs land? I mentioned it during my folio session at LSFMM, but didn't put a huge emphasis on it. For XFS, writeback should already be in progress on other pages if we're getting to the point of trying to call ->writepage() in vmscan. Surely this is also true for other filesystems?