Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752062AbdDCWpb (ORCPT ); Mon, 3 Apr 2017 18:45:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55370 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751734AbdDCWpa (ORCPT ); Mon, 3 Apr 2017 18:45:30 -0400 Date: Mon, 3 Apr 2017 15:45:28 -0700 From: Andrew Morton To: Minchan Kim Cc: , Sergey Senozhatsky , , Jens Axboe , Hannes Reinecke , Johannes Thumshirn Subject: Re: [PATCH 1/5] zram: handle multiple pages attached bio's bvec Message-Id: <20170403154528.6470165dd791cf8a23ae57c8@linux-foundation.org> In-Reply-To: <1491196653-7388-2-git-send-email-minchan@kernel.org> References: <1491196653-7388-1-git-send-email-minchan@kernel.org> <1491196653-7388-2-git-send-email-minchan@kernel.org> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1465 Lines: 37 On Mon, 3 Apr 2017 14:17:29 +0900 Minchan Kim wrote: > Johannes Thumshirn reported system goes the panic when using NVMe over > Fabrics loopback target with zram. > > The reason is zram expects each bvec in bio contains a single page > but nvme can attach a huge bulk of pages attached to the bio's bvec > so that zram's index arithmetic could be wrong so that out-of-bound > access makes panic. > > It can be solved by limiting max_sectors with SECTORS_PER_PAGE like > [1] but it makes zram slow because bio should split with each pages > so this patch makes zram aware of multiple pages in a bvec so it > could solve without any regression. > > [1] 0bc315381fe9, zram: set physical queue limits to avoid array out of > bounds accesses This isn't a cleanup - it fixes a panic (or is it a BUG or is it an oops, or...) How serious is this bug? Should the fix be backported into -stable kernels? etc. A better description of the bug's behaviour would be appropriate. > Cc: Jens Axboe > Cc: Hannes Reinecke > Reported-by: Johannes Thumshirn > Tested-by: Johannes Thumshirn > Reviewed-by: Johannes Thumshirn > Signed-off-by: Johannes Thumshirn > Signed-off-by: Minchan Kim This signoff trail is confusing. It somewhat implies that Johannes authored the patch which I don't think is the case?