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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 2E78CC433DB for ; Fri, 5 Mar 2021 08:27:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E698165016 for ; Fri, 5 Mar 2021 08:27:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229469AbhCEI1L (ORCPT ); Fri, 5 Mar 2021 03:27:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:47412 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229494AbhCEI1L (ORCPT ); Fri, 5 Mar 2021 03:27:11 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 502B265014; Fri, 5 Mar 2021 08:27:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614932830; bh=BOASgRiX/anyBYwyGt5CoZ1avHZlm10qLQx9FzJQMQQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rmTOuV1dgAPy4LsKiOB1P2ZRT8wBd6gxH+xJMcSDY+xbjp76e+87zg4v4Sh3L6DmF PlS3kc4euNYVnjiGvdpSIlCYDaUlIsyfifKhLdKW32m+u+0A1JXKophgL8+7zRGN3v sOFf1PIFHxcSaXCbqlVnX87jKkOOfWOv3ONtHfCo= Date: Fri, 5 Mar 2021 09:27:08 +0100 From: Greg Kroah-Hartman To: Anthony Iliopoulos Cc: Jens Axboe , Andrew Morton , Matthew Wilcox , stable@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH STABLE 5.10 5.11] swap: fix swapfile page to sector mapping Message-ID: References: <20210304150824.29878-1-ailiop@suse.com> <20210304150824.29878-5-ailiop@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Mar 04, 2021 at 10:17:08PM +0100, Anthony Iliopoulos wrote: > On Thu, Mar 04, 2021 at 05:58:49PM +0100, Greg Kroah-Hartman wrote: > > On Thu, Mar 04, 2021 at 05:30:00PM +0100, Anthony Iliopoulos wrote: > > > On Thu, Mar 04, 2021 at 04:16:26PM +0100, Greg Kroah-Hartman wrote: > > > > On Thu, Mar 04, 2021 at 04:08:24PM +0100, Anthony Iliopoulos wrote: > > > > > commit caf6912f3f4af7232340d500a4a2008f81b93f14 upstream. > > > > > > > > No, this does not look like that commit. > > > > > > > > Why can I not just take caf6912f3f4a ("swap: fix swapfile read/write > > > > offset") directly for 5.10 and 5.11? WHat has changed to prevent that? > > > > > > You're right of course, the upstream fix applies even on v5.4 so you > > > could just take it directly for those branches if this is preferable. > > > > But, that commit says it fixes 48d15436fde6 ("mm: remove get_swap_bio"), > > which is NOT what you are saying here in these patches. > > It is admittedly a bit confusing as the upstream commit fixes two issues > in one swoop: > > - the bug which was introduced in v5.12-rc1 via 48d15436fde6 ("mm: > remove get_swap_bio"), which affected swapfiles running on regular > block devices, in addition to: > > - an identical bug which up until 48d15436fde6 was only applicable to > swapfiles on top of blockdevs that can do page io without the block > layer, which was introduced with dd6bd0d9c7db ("swap: use > bdev_read_page() / bdev_write_page()") > > > So which is it? Is there a problem in 5.11 and older kernels > > (48d15436fde6 ("mm: remove get_swap_bio") showed up in 5.12-rc1), that > > requires this fix, or is there nothing needed to be backported? > > The second point/bug mentioned above is present on 5.11 and all older > kernels, so some form of this fix is required. > > > As a note, I've been running swapfiles on 5.11 and earlier just fine for > > a very long time now, so is this really an issue? > > Yes there is an issue on all kernels since v3.16-rc1 when dd6bd0d9c7db > was introduced, but it is applicable only to setups with swapfiles on > filesystems sitting on top of brd, zram, btt or pmem. > > I can trivially reproduce this e.g. on v5.11 by creating a swapfile on > top of a zram or pmem blockdev and pushing the system to swap out pages, > at which point it corrupts filesystem blocks that don't belong to the > swapfile. Ok, thanks for the detailed description, all now queued up. greg k-h