From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756358AbdEUCpt (ORCPT ); Sat, 20 May 2017 22:45:49 -0400 Received: from imap.thunk.org ([74.207.234.97]:46382 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756066AbdEUCpr (ORCPT ); Sat, 20 May 2017 22:45:47 -0400 Date: Sat, 20 May 2017 22:45:44 -0400 From: "Theodore Ts'o" To: Konstantin Khlebnikov Cc: Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] ext4: handle the rest of ext4_mb_load_buddy() ENOMEM errors Message-ID: <20170521024544.udju6nbsfdanf5pl@thunk.org> Mail-Followup-To: Theodore Ts'o , Konstantin Khlebnikov , Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <149517779388.33359.16474190951431954772.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <149517779388.33359.16474190951431954772.stgit@buzz> User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 19, 2017 at 10:09:54AM +0300, Konstantin Khlebnikov wrote: > I've got another report about breaking ext4 by ENOMEM error returned from > ext4_mb_load_buddy() caused by memory shortage in memory cgroup. > This time inside ext4_discard_preallocations(). > > This patch replaces ext4_error() with ext4_warning() where errors returned > from ext4_mb_load_buddy() are not fatal and handled by caller: > * ext4_mb_discard_group_preallocations() - called before generating ENOSPC, > we'll try to discard other group or return ENOSPC into user-space. > * ext4_trim_all_free() - just stop trimming and return ENOMEM from ioctl. > > Some callers cannot handle errors, thus __GFP_NOFAIL is used for them: > * ext4_discard_preallocations() > * ext4_mb_discard_lg_preallocations() > > The only unclear case is ext4_group_add_blocks(), probably ext4_std_error() > should handle ENOMEM as warning and don't break filesystem. > > Fixes: adb7ef600cc9 ("ext4: use __GFP_NOFAIL in ext4_free_blocks()") > Signed-off-by: Konstantin Khlebnikov Thanks, applied. - Ted