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 X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EF83C433E3 for ; Fri, 21 Aug 2020 06:01:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F11B3214F1 for ; Fri, 21 Aug 2020 06:01:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="IyN+5kWg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726767AbgHUGBn (ORCPT ); Fri, 21 Aug 2020 02:01:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725908AbgHUGBn (ORCPT ); Fri, 21 Aug 2020 02:01:43 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A920DC061385; Thu, 20 Aug 2020 23:01:42 -0700 (PDT) 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=pMtaQn3ay+ptYcRtyTRCbYkpEwBnxB9UnKg+LUEYRH8=; b=IyN+5kWgoiB0LUFfan3Y0ec/RA PfrKZVDCY+Ia1MFgZE4U/08qG0GYXfJaQ/VCn9eDJnM8Fpe+AAe4D+E206rzvBU0TCElQBDoZB5PO ZYIeUX0M08LkEw+xnpc8B5FZB7ExH68BaD/fjyG/A9c0qpCgha/XyAAA+Oj5lCXUkIiwJEEc6nuFL Y6wgGdIYNXVWXgyoyIXxdfU5zHiiZzmsD4HSsNaOsXhVm5roDk57qbZREn5B2k3azZQKfJ8jqcgjC 8CZDq3y217y1KELbmiXvNF+Yr9g/6QzjvAYkh/VYPjjfP/Gp6muiD1XiXiGX45PXCN5t+B//lyObM 4hYnP27g==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k907P-0008PR-Gh; Fri, 21 Aug 2020 06:01:39 +0000 Date: Fri, 21 Aug 2020 07:01:39 +0100 From: Christoph Hellwig To: Dave Chinner Cc: Anju T Sudhakar , hch@infradead.org, darrick.wong@oracle.com, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, riteshh@linux.ibm.com Subject: Re: [PATCH] iomap: Fix the write_count in iomap_add_to_ioend(). Message-ID: <20200821060139.GB31091@infradead.org> References: <20200819102841.481461-1-anju@linux.vnet.ibm.com> <20200820231140.GE7941@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200820231140.GE7941@dread.disaster.area> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Aug 21, 2020 at 09:11:40AM +1000, Dave Chinner wrote: > On Wed, Aug 19, 2020 at 03:58:41PM +0530, Anju T Sudhakar wrote: > > From: Ritesh Harjani > > > > __bio_try_merge_page() may return same_page = 1 and merged = 0. > > This could happen when bio->bi_iter.bi_size + len > UINT_MAX. > > Ummm, silly question, but exactly how are we getting a bio that > large in ->writepages getting built? Even with 64kB pages, that's a > bio with 2^16 pages attached to it. We shouldn't be building single > bios in writeback that large - what storage hardware is allowing > such huge bios to be built? (i.e. can you dump all the values in > /sys/block//queue/* for that device for us?) NVMe controller should not have a problem with such huge I/O, especially if they support SGLs (extent based I/O :)) instead of the default dumb PRP scheme. Higher end SCSI controller should also have huge limits.