Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752001AbbLVGCe (ORCPT ); Tue, 22 Dec 2015 01:02:34 -0500 Received: from mail-pf0-f170.google.com ([209.85.192.170]:35637 "EHLO mail-pf0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750772AbbLVGCc (ORCPT ); Tue, 22 Dec 2015 01:02:32 -0500 Date: Mon, 21 Dec 2015 21:02:27 -0900 From: Kent Overstreet To: "Artem S. Tashkinov" Cc: Junichi Nomura , Tejun Heo , "Artem S. Tashkinov" , Christoph Hellwig , Ming Lin , Jens Axboe , Linus Torvalds , Steven Whitehouse , IDE-ML , Linux Kernel Mailing List , Ming Lei Subject: Re: IO errors after "block: remove bio_get_nr_vecs()" Message-ID: <20151222060227.GD26544@kmo-pixel> References: <20151221193550.GM4026@mtj.duckdns.org> <20151221200721.GN4026@mtj.duckdns.org> <20151221210811.GO4026@mtj.duckdns.org> <20151222035944.GG20661@kmo-pixel> <20151222052611.GA10487@xzibit.linux.bs1.fc.nec.co.jp> <20151222053849.GB26544@kmo-pixel> <62de5f2365e58309503720ec3ad2fafd@lycos.com> <20151222055510.GC26544@kmo-pixel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2085 Lines: 52 On Tue, Dec 22, 2015 at 10:59:09AM +0500, Artem S. Tashkinov wrote: > On 2015-12-22 10:55, Kent Overstreet wrote: > >On Tue, Dec 22, 2015 at 10:52:37AM +0500, Artem S. Tashkinov wrote: > >>On 2015-12-22 10:38, Kent Overstreet wrote: > >>>On Tue, Dec 22, 2015 at 05:26:12AM +0000, Junichi Nomura wrote: > >>>>On 12/22/15 12:59, Kent Overstreet wrote: > >>>>> reproduced it with 32 bit pae: > >>>>> > >>>>>> 1. Exclude memory above 4G line with boot param "max_addr=4G". > >>>>> > >>>>> doesn't work - max_addr=1G doesn't work either > >>>>> > >>>>>> 2. Disable highmem with "highmem=0". > >>>>> > >>>>> works! > >>>>> > >>>>>> 3. Try booting 64bit kernel. > >>>>> > >>>>> works > >>>> > >>>>blk_queue_bio() does split then bounce, which makes the segment > >>>>counting based on pages before bouncing and could go wrong. > >>>> > >>>>What do you think of a patch like this? > >>> > >>>Artem, can you give this patch a try? > >> > >> > >>This patch ostensibly fixes the issue - at least I cannot immediately > >>reproduce it. You can count me in as "Tested-by: Artem S. Tashkinov" > > > >Let's all contemplate the fact that blk_segment_map_sg() _overrunning the > >end of > >the provided sglist_ was this much of a clusterfuck to debug. > > From the look of it this fix has nothing to do with PAE, so then why only > PAE users like me were affected by the original > (b54ffb73cadcdcff9cc1ae0e11f502407e3e2e4c) patch? The amusing thing is that I doubt PAE actually requires bouncing - addressing limits come from the device, not the cpu. But evidently in PAE mode, the block layer is in fact bouncing bios. Probably from some default setting in the queue limits that no one ever looks at. The whole queue limits design is an atrocity, it leads to exactly this kind of crap where no one can predict the actual behaviour of any given setup. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/