Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in freeze_super
======================================================
WARNING: possible circular locking dependency detected
6.2.0-rc2-syzkaller-00127-g69b41ac87e4a-dirty #0 Not tainted
------------------------------------------------------
kworker/1:1H/93 is trying to acquire lock:
ffff88802666e0e0 (&type->s_umount_key#50){+.+.}-{3:3}, at: freeze_super+0x45/0x420 fs/super.c:1655
but task is already holding lock:
ffffc90002587d00 ((work_completion)(&(&gl->gl_work)->work)){+.+.}-{0:0}, at: process_one_work+0x831/0xdb0 kernel/workqueue.c:2264
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 ((work_completion)(&(&gl->gl_work)->work)){+.+.}-{0:0}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
process_one_work+0x852/0xdb0 kernel/workqueue.c:2265
worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
-> #1 ((wq_completion)glock_workqueue){+.+.}-{0:0}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__flush_workqueue+0x17c/0x16d0 kernel/workqueue.c:2809
gfs2_gl_hash_clear+0xa3/0x300 fs/gfs2/glock.c:2191
gfs2_put_super+0x862/0x8d0 fs/gfs2/super.c:627
generic_shutdown_super+0x130/0x310 fs/super.c:492
kill_block_super+0x79/0xd0 fs/super.c:1386
deactivate_locked_super+0xa7/0xf0 fs/super.c:332
cleanup_mnt+0x494/0x520 fs/namespace.c:1291
task_work_run+0x243/0x300 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0x124/0x150 kernel/entry/common.c:171
exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:203
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:296
do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
-> #0 (&type->s_umount_key#50){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
down_write+0x9c/0x270 kernel/locking/rwsem.c:1562
freeze_super+0x45/0x420 fs/super.c:1655
freeze_go_sync+0x178/0x340 fs/gfs2/glops.c:577
do_xmote+0x34d/0x13d0 fs/gfs2/glock.c:708
glock_work_func+0x2c2/0x450 fs/gfs2/glock.c:1056
process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
other info that might help us debug this:
Chain exists of:
&type->s_umount_key#50 --> (wq_completion)glock_workqueue --> (work_completion)(&(&gl->gl_work)->work)
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock((work_completion)(&(&gl->gl_work)->work));
lock((wq_completion)glock_workqueue);
lock((work_completion)(&(&gl->gl_work)->work));
lock(&type->s_umount_key#50);
*** DEADLOCK ***
2 locks held by kworker/1:1H/93:
#0: ffff888012bf7d38 ((wq_completion)glock_workqueue){+.+.}-{0:0}, at: process_one_work+0x7f2/0xdb0
#1: ffffc90002587d00 ((work_completion)(&(&gl->gl_work)->work)){+.+.}-{0:0}, at: process_one_work+0x831/0xdb0 kernel/workqueue.c:2264
stack backtrace:
CPU: 1 PID: 93 Comm: kworker/1:1H Not tainted 6.2.0-rc2-syzkaller-00127-g69b41ac87e4a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: glock_workqueue glock_work_func
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106
check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
down_write+0x9c/0x270 kernel/locking/rwsem.c:1562
freeze_super+0x45/0x420 fs/super.c:1655
freeze_go_sync+0x178/0x340 fs/gfs2/glops.c:577
do_xmote+0x34d/0x13d0 fs/gfs2/glock.c:708
glock_work_func+0x2c2/0x450 fs/gfs2/glock.c:1056
process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Tested on:
commit: 69b41ac8 Merge tag 'for-6.2-rc2-tag' of git://git.kern..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=154506dc480000
kernel config: https://syzkaller.appspot.com/x/.config?x=9babfdc3dd4772d0
dashboard link: https://syzkaller.appspot.com/bug?extid=f51cb4b9afbd87ec06f2
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=11d59a52480000
