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 629F9C4332F for ; Mon, 7 Nov 2022 20:28:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BA3476B0071; Mon, 7 Nov 2022 15:28:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B2C046B0072; Mon, 7 Nov 2022 15:28:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9CC8A6B0073; Mon, 7 Nov 2022 15:28:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 8AE226B0071 for ; Mon, 7 Nov 2022 15:28:10 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 65AC54100F for ; Mon, 7 Nov 2022 20:28:10 +0000 (UTC) X-FDA: 80107783140.22.DAD87A5 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf19.hostedemail.com (Postfix) with ESMTP id 8F8731A0002 for ; Mon, 7 Nov 2022 20:28:08 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 01587CE177C; Mon, 7 Nov 2022 20:28:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 08E6AC433C1; Mon, 7 Nov 2022 20:28:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1667852883; bh=aREzJ82LETov4vyswWcOqUzCcN34+DHGiNT7LfzWG0Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DHCP+2OjA8EgywON23IT4+vnOk/fdY7XK9Rg4447v3d3sxZLqSrcM950Y78FKY3gu BVGb1uQZnSqZzAG9PCl2ZSo7NSXyEZ6DAbdiIDVlLKuV0jolBGi+Grh1uPsR+O4kiy ArHLLs5zXjOyZfsx3CMI/OXFoBMbYIAf4jN2jp8M= Date: Mon, 7 Nov 2022 12:28:02 -0800 From: Andrew Morton To: Brian Foster Cc: linux-mm@kvack.org Subject: Re: [PATCH] filemap: skip range writeback if end offset precedes start Message-Id: <20221107122802.d214dd0a3c546d3a35c71e9c@linux-foundation.org> In-Reply-To: References: <20221028125428.976549-1-bfoster@redhat.com> <20221030215100.f5e7116e848077c96d86591d@linux-foundation.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667852889; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=GyABFjN2/5PKf+NfJj00/ajcLJd/GKXBHhfQizn8Z+A=; b=HZm3tprjIzi3Di/QH/7I9yAEqL+ESItuWrrEc3+G53MZech5DD4SKbZQm5eTdfLbfhOzpC u2zGng954hQfJBNeg4P5D4tVQPbcRKNJGnNoCbshdujzHcSVM5gqmizY2rJX+kuDZ2pHL1 5fHBNRHA7wzIFXiFgKx1oJ9U4MxSkQg= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=DHCP+2Oj; spf=pass (imf19.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667852889; a=rsa-sha256; cv=none; b=AGZ9a5AyDEbhz/I1pwUlyOuqzV4eAdPDDDa2zh4zDIuKjuF9o6oS/rBE93IO4blEJKcxAt iLgKmm1VDOggErqhbJkvmfCMXjVHj4WkGfnNpXXYOJ4c17ysk4Auwb2wIMavYoXJ4Ck6ZD eAmHErr+2P4o5gDz0ImOuZUrKCqiq60= X-Rspamd-Queue-Id: 8F8731A0002 X-Rspam-User: X-Rspamd-Server: rspam08 Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=DHCP+2Oj; spf=pass (imf19.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Stat-Signature: zre4jfky9aj5muimdesp3y4xp8n7w9qa X-HE-Tag: 1667852888-686781 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 Mon, 7 Nov 2022 11:33:46 -0500 Brian Foster wrote: > Perhaps a good starting point would be to wrap the check in > this patch with a WARN_ON_ONCE() and let it soak in -next for a while? > That would avoid excessive noise from repetitive callers [1] but still > allow those callsites to be identified/fixed. If there is some really > weird fdatawrite-only caller that conflicts, the change could always be > loosened up from there (as unlikely as that seems).. Hm? Sounds reasonable. Please let's be clear in the changelog why we're adding this. I mean, we could add a zillion checks everywhere for misbehaving callers. Why choose this one place in particular?