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 346C4C4332F for ; Fri, 11 Nov 2022 09:09:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233366AbiKKJJz (ORCPT ); Fri, 11 Nov 2022 04:09:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232921AbiKKJJx (ORCPT ); Fri, 11 Nov 2022 04:09:53 -0500 Received: from mout.gmx.net (mout.gmx.net [212.227.17.21]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14A0365D7; Fri, 11 Nov 2022 01:09:51 -0800 (PST) Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.net (mrgmx104 [212.227.17.174]) with ESMTPSA (Nemesis) id 1MiJVG-1pVUgY2FMM-00fS1p; Fri, 11 Nov 2022 10:09:30 +0100 Message-ID: Date: Fri, 11 Nov 2022 17:09:18 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.0 Content-Language: en-US To: ChenXiaoSong , clm@fb.com, josef@toxicpanda.com, dsterba@suse.com Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, zhangxiaoxu5@huawei.com References: <20221111090212.2266807-1-chenxiaosong2@huawei.com> From: Qu Wenruo Subject: Re: [PATCH v2] btrfs: qgroup: fix sleep from invalid context bug in update_qgroup_limit_item() In-Reply-To: <20221111090212.2266807-1-chenxiaosong2@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K1:adN0BvpY9LFW83nGRg2sI4NzI0n5q9vd7DcF/upA6ogrTnaTe++ 7UgwSGVj7uFsEiPD/a74sSIZRNXL92kHgV3enPbnl4N4/icc94245Er872ezOoxSYUywdQn r9GhcCBp1Ff8jg8f1KHcivRYFWgdj30tg1m9ueoXmmazzd+anouruVLZgBEuVFVu0OYjuNO C3O6AxRhGwvM5d+HgBUKQ== UI-OutboundReport: notjunk:1;M01:P0:XhtG/YgKL7A=;aHOHIZ1BRv8H/ZdpVFE23iyv8b1 Tnd/2h5C79fwMW2l5585UL5TtvZLPnMKlBk2bQB174cn8KX730VMd4XRkhf05CW3u//dIzq/U TmhpZk3G63vrQFotqdDhcPKsfOVX7B08/AMXFJsagLbTazTpCLV226L8FIlA+k29AcrUbqTSd x+KZX78D8cEDGeMGKIbo0m6UZzVxahaBl7JCTs73R4xAIsG3ZDuroPj8ML/ENvwQTPNDYNtX5 gFDodHJJXBUyUskXs4ln6luH5yTnZ49M+FxRITeonfmDNpEGEhxH3rgAsQBysgeatw/1dIIwG n3w+YPV/McTzCmrWYLkOsd5kmlr9ljrqILPQ5PnNAYnelY5ffbIGIn+6BiNrhvazRwZUVXbBy Bo/yJl/GD19C1QiG3h7Kvpnlb4BE55//37X4COGaWY0WSGw6zbEgQfKuuGXTw4UllnxzrVi7P 7KZ8j7MqCNqmkDqsmm7OqwFl/M8rIO4ogWS5wcz6UI8IueHllF76MnJrPy7rrHPjbWQcnylab E24XOMkFhoM9KUBJqWkKmwS3v9axoTf3HWbf/XmZL4v1gJfMOz0yIQQZcJeljjLOt/KO2p8Ex IKoQXcVEf50A8T/stgZSl3+pyI/VJoFM+a3vlBHq7NQ+yNj6HD0KeUAmqc03bU5KsnmfdH92h gekmvftQrkLa6mFox7DgEvth9zhLr2OYUDcqIxn5DvsF4SNffDfbQSMNYKFbHiUXHpDNOOKVh TShgBX777AvQnjJrK6mPdeQE7OdLCoe8CWpDM/wu+dCHkm51/RFekQA9hXE2eXu9QfUyWtuHS stNyJxicdCH9QcYb2KA/tDEVrcIGzMlbbxaB3TbeIEysf67L3wwJUEKSQ8AMYUbjfxMi9SCb9 dCamuhE7YzVXjJncwnbzVj9qTKsFFWeCiorWTAQaZ8K9cja/kSITA4g0qg/R/OI2bWyDjrpqx tC196Tfqufd0bFU/q3etnesnGss= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/11/11 17:02, ChenXiaoSong wrote: > Syzkaller reported BUG as follows: > > BUG: sleeping function called from invalid context at > include/linux/sched/mm.h:274 > Call Trace: > > dump_stack_lvl+0xcd/0x134 > __might_resched.cold+0x222/0x26b > kmem_cache_alloc+0x2e7/0x3c0 > update_qgroup_limit_item+0xe1/0x390 > btrfs_qgroup_inherit+0x147b/0x1ee0 > create_subvol+0x4eb/0x1710 > btrfs_mksubvol+0xfe5/0x13f0 > __btrfs_ioctl_snap_create+0x2b0/0x430 > btrfs_ioctl_snap_create_v2+0x25a/0x520 > btrfs_ioctl+0x2a1c/0x5ce0 > __x64_sys_ioctl+0x193/0x200 > do_syscall_64+0x35/0x80 > > Fix this by delaying the limit item updates until unlock the spin lock. The overall idea is way better now. But sorry that I didn't immediately find out the best solution at the first glance. In fact, your v2 path just lets me remember what is the correct way to handle such situation. > > Signed-off-by: ChenXiaoSong > --- > fs/btrfs/qgroup.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c > index 9334c3157c22..2792d63c0da4 100644 > --- a/fs/btrfs/qgroup.c > +++ b/fs/btrfs/qgroup.c [...] > @@ -2985,6 +2978,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid, > dstgroup->max_excl = srcgroup->max_excl; > dstgroup->rsv_rfer = srcgroup->rsv_rfer; > dstgroup->rsv_excl = srcgroup->rsv_excl; > + update_limit = true; > > qgroup_dirty(fs_info, dstgroup); > qgroup_dirty(fs_info, srcgroup); You caught the "if (srcid)" branch, which also changed the limit/rfer/excl numbers of the destination qgroup, but didn't call update_qgroup_limit_item(). But if you check the function qgroup_dirty() a little deeper, you can find out that, qgroup_dirty() will move the target qgroup into fs_info->dirty_qgroups list. And later at btrfs_run_qgroups() (which is called during btrfs_commit_transaction(), and also after create_pending_snapshots()), we will update the quota tree to reflect the result. So this means, all you need is just call qgroup_dirty() on @dstqgroup, and call it a day. Everything else will be properly handled. Sorry I didn't notice this earlier... Thanks, Qu > @@ -3053,6 +3047,12 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid, > > unlock: > spin_unlock(&fs_info->qgroup_lock); > + if (update_limit && update_qgroup_limit_item(trans, dstgroup)) { > + qgroup_mark_inconsistent(fs_info); > + btrfs_info(fs_info, > + "unable to update quota limit for %llu", > + dstgroup->qgroupid); > + } > if (!ret) > ret = btrfs_sysfs_add_one_qgroup(fs_info, dstgroup); > out: