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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 254D4C433F5 for ; Fri, 18 Feb 2022 07:52:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232200AbiBRHwf (ORCPT ); Fri, 18 Feb 2022 02:52:35 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:51628 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232171AbiBRHwd (ORCPT ); Fri, 18 Feb 2022 02:52:33 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62B7F580E8; Thu, 17 Feb 2022 23:52:16 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id E0E7AB82537; Fri, 18 Feb 2022 07:52:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9F70C340ED; Fri, 18 Feb 2022 07:52:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645170733; bh=V+9C48iv9XRk+MUoKRdXyp5e9Ugr2dXDUyMumpaYQ6g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=J50nw6T8dG5KzH/M8aFe8tHATxgNAosOGLEUAPRWPC99g6+YSWDb3TC1slK7qRKWZ r78c+ZEleASEcNm80gohZLsLprX9bBCL6K6KaMuVr2gqJBrcyOrVrFUF3a4hahRmSw sXqJy5WNvMLvQQMBN93Q3HkJKsbSpOSsUalvBZyA= Date: Fri, 18 Feb 2022 08:51:54 +0100 From: Greg Kroah-Hartman To: Theodore Ts'o Cc: John Hubbard , Lee Jones , linux-ext4@vger.kernel.org, Christoph Hellwig , Dave Chinner , Goldwyn Rodrigues , "Darrick J . Wong" , Bob Peterson , Damien Le Moal , Andreas Gruenbacher , Ritesh Harjani , Johannes Thumshirn , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, cluster-devel@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [REPORT] kernel BUG at fs/ext4/inode.c:2620 - page_buffers() Message-ID: References: <82d0f4e4-c911-a245-4701-4712453592d9@nvidia.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: linux-ext4@vger.kernel.org On Thu, Feb 17, 2022 at 11:08:38PM -0500, Theodore Ts'o wrote: > On Thu, Feb 17, 2022 at 05:06:45PM -0800, John Hubbard wrote: > > Yes. And looking at the pair of backtraces below, this looks very much > > like another aspect of the "get_user_pages problem" [1], originally > > described in Jan Kara's 2018 email [2]. > > Hmm... I just posted my analysis, which tracks with yours; but I had > forgotten about Jan's 2018 e-mail on the matter. > > > I'm getting close to posting an RFC for the direct IO conversion to > > FOLL_PIN, but even after that, various parts of the kernel (reclaim, > > filesystems/block layer) still need to be changed so as to use > > page_maybe_dma_pinned() to help avoid this problem. There's a bit > > more than that, actually. > > The challenge is that fixing this "the right away" is probably not > something we can backport into an LTS kernel, whether it's 5.15 or > 5.10... or 4.19. Don't worry about stable backports to start with. Do it the "right way" first and then we can consider if it needs to be backported or not. thanks, greg k-h