[PATCH 5.10 101/129] ext4: fix bug_on in start_this_handle during umount filesystem

Greg Kroah-Hartman
2022-05-04T17:06:42Z

From: Ye Bin <yebin10@huawei.com>

[ Upstream commit b98535d091795a79336f520b0708457aacf55c67 ]

We got issue as follows:
------------[ cut here ]------------
kernel BUG at fs/jbd2/transaction.c:389!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 9 PID: 131 Comm: kworker/9:1 Not tainted 5.17.0-862.14.0.6.x86_64-00001-g23f87daf7d74-dirty #197
Workqueue: events flush_stashed_error_work
RIP: 0010:start_this_handle+0x41c/0x1160
RSP: 0018:ffff888106b47c20 EFLAGS: 00010202
RAX: ffffed10251b8400 RBX: ffff888128dc204c RCX: ffffffffb52972ac
RDX: 0000000000000200 RSI: 0000000000000004 RDI: ffff888128dc2050
RBP: 0000000000000039 R08: 0000000000000001 R09: ffffed10251b840a
R10: ffff888128dc204f R11: ffffed10251b8409 R12: ffff888116d78000
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff888128dc2000
FS: 0000000000000000(0000) GS:ffff88839d680000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001620068 CR3: 0000000376c0e000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
jbd2__journal_start+0x38a/0x790
jbd2_journal_start+0x19/0x20
flush_stashed_error_work+0x110/0x2b3
process_one_work+0x688/0x1080
worker_thread+0x8b/0xc50
kthread+0x26f/0x310
ret_from_fork+0x22/0x30
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---

Above issue may happen as follows:
umount read procfs error_work
ext4_put_super
flush_work(&sbi->s_error_work);

ext4_mb_seq_groups_show
ext4_mb_load_buddy_gfp
ext4_mb_init_group
ext4_mb_init_cache
ext4_read_block_bitmap_nowait
ext4_validate_block_bitmap
ext4_error
ext4_handle_error
schedule_work(&EXT4_SB(sb)->s_error_work);

ext4_unregister_sysfs(sb);
jbd2_journal_destroy(sbi->s_journal);
journal_kill_thread
journal->j_flags |= JBD2_UNMOUNT;

flush_stashed_error_work
jbd2_journal_start
start_this_handle
BUG_ON(journal->j_flags & JBD2_UNMOUNT);

To solve this issue, we call 'ext4_unregister_sysfs() before flushing
s_error_work in ext4_put_super().

Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20220322012419.725457-1-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/super.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5e6c03458317..3e26edeca8c7 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1176,18 +1176,23 @@ static void ext4_put_super(struct super_block *sb)
int aborted = 0;
int i, err;

- ext4_unregister_li_request(sb);
- ext4_quota_off_umount(sb);
-
- destroy_workqueue(sbi->rsv_conversion_wq);
-
/*
* Unregister sysfs before destroying jbd2 journal.
* Since we could still access attr_journal_task attribute via sysfs
* path which could have sbi->s_journal->j_task as NULL
+ * Unregister sysfs before flush sbi->s_error_work.
+ * Since user may read /proc/fs/ext4/xx/mb_groups during umount, If
+ * read metadata verify failed then will queue error work.
+ * flush_stashed_error_work will call start_this_handle may trigger
+ * BUG_ON.
*/
ext4_unregister_sysfs(sb);

+ ext4_unregister_li_request(sb);
+ ext4_quota_off_umount(sb);
+
+ destroy_workqueue(sbi->rsv_conversion_wq);
+
if (sbi->s_journal) {
aborted = is_journal_aborted(sbi->s_journal);
err = jbd2_journal_destroy(sbi->s_journal);
--
2.35.1