======================================================
WARNING: possible circular locking dependency detected
5.16.0-rc8-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/9709 is trying to acquire lock:
ffff8880231b7938 ((wq_completion)loop1){+.+.}-{0:0}, at: flush_workqueue+0x172/0x16b0 kernel/workqueue.c:2818

but task is already holding lock:
ffff88801af69360 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x6d/0x9b0 drivers/block/loop.c:1106

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (&lo->lo_mutex){+.+.}-{3:3}:
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       __mutex_lock_common+0x1d3/0x2490 kernel/locking/mutex.c:607
       __mutex_lock kernel/locking/mutex.c:740 [inline]
       mutex_lock_killable_nested+0x1a/0x20 kernel/locking/mutex.c:807
       lo_open+0x68/0x100 drivers/block/loop.c:1733
       blkdev_get_whole+0x8c/0x3d0 block/bdev.c:671
       blkdev_get_by_dev+0x2ff/0xba0 block/bdev.c:826
       blkdev_open+0x137/0x2f0 block/fops.c:501
       do_dentry_open+0x78b/0x1020 fs/open.c:822
       do_open fs/namei.c:3426 [inline]
       path_openat+0x2896/0x3660 fs/namei.c:3559
       do_filp_open+0x277/0x4f0 fs/namei.c:3586
       do_sys_openat2+0x13b/0x500 fs/open.c:1212
       do_sys_open fs/open.c:1228 [inline]
       __do_sys_openat fs/open.c:1244 [inline]
       __se_sys_openat fs/open.c:1239 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1239
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #6 (&disk->open_mutex){+.+.}-{3:3}:
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       __mutex_lock_common+0x1d3/0x2490 kernel/locking/mutex.c:607
       __mutex_lock kernel/locking/mutex.c:740 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
       blkdev_get_by_dev+0xf7/0xba0 block/bdev.c:817
       swsusp_check+0xb0/0x2b0 kernel/power/swap.c:1520
       software_resume+0xc8/0x3d0 kernel/power/hibernate.c:979
       resume_store+0xdc/0x120 kernel/power/hibernate.c:1181
       kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2162 [inline]
       new_sync_write fs/read_write.c:503 [inline]
       vfs_write+0xb11/0xe90 fs/read_write.c:590
       ksys_write+0x18f/0x2c0 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #5 (system_transition_mutex/1){+.+.}-{3:3}:
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       __mutex_lock_common+0x1d3/0x2490 kernel/locking/mutex.c:607
       __mutex_lock kernel/locking/mutex.c:740 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
       software_resume+0x7a/0x3d0 kernel/power/hibernate.c:934
       resume_store+0xdc/0x120 kernel/power/hibernate.c:1181
       kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2162 [inline]
       new_sync_write fs/read_write.c:503 [inline]
       vfs_write+0xb11/0xe90 fs/read_write.c:590
       ksys_write+0x18f/0x2c0 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #4 (&of->mutex){+.+.}-{3:3}:
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       __mutex_lock_common+0x1d3/0x2490 kernel/locking/mutex.c:607
       __mutex_lock kernel/locking/mutex.c:740 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
       kernfs_seq_start+0x50/0x3b0 fs/kernfs/file.c:112
       seq_read_iter+0x401/0xdc0 fs/seq_file.c:225
       call_read_iter include/linux/fs.h:2156 [inline]
       new_sync_read fs/read_write.c:400 [inline]
       vfs_read+0xaf9/0xe60 fs/read_write.c:481
       ksys_read+0x18f/0x2c0 fs/read_write.c:619
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #3 (&p->lock){+.+.}-{3:3}:
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       __mutex_lock_common+0x1d3/0x2490 kernel/locking/mutex.c:607
       __mutex_lock kernel/locking/mutex.c:740 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792
       seq_read_iter+0xb6/0xdc0 fs/seq_file.c:182
       call_read_iter include/linux/fs.h:2156 [inline]
       generic_file_splice_read+0x482/0x760 fs/splice.c:311
       do_splice_to fs/splice.c:796 [inline]
       splice_direct_to_actor+0x45f/0xd00 fs/splice.c:870
       do_splice_direct+0x291/0x3e0 fs/splice.c:979
       do_sendfile+0x6fe/0x1040 fs/read_write.c:1245
       __do_sys_sendfile64 fs/read_write.c:1310 [inline]
       __se_sys_sendfile64+0x171/0x1d0 fs/read_write.c:1296
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #2 (sb_writers#3){.+.+}-{0:0}:
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1810 [inline]
       sb_start_write include/linux/fs.h:1880 [inline]
       file_start_write include/linux/fs.h:3008 [inline]
       lo_write_bvec drivers/block/loop.c:242 [inline]
       lo_write_simple drivers/block/loop.c:265 [inline]
       do_req_filebacked drivers/block/loop.c:494 [inline]
       loop_handle_cmd drivers/block/loop.c:1857 [inline]
       loop_process_work+0x1682/0x22d0 drivers/block/loop.c:1897
       process_one_work+0x853/0x1140 kernel/workqueue.c:2298
       worker_thread+0xac1/0x1320 kernel/workqueue.c:2445
       kthread+0x468/0x490 kernel/kthread.c:327
       ret_from_fork+0x1f/0x30

-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       process_one_work+0x827/0x1140 kernel/workqueue.c:2274
       worker_thread+0xac1/0x1320 kernel/workqueue.c:2445
       kthread+0x468/0x490 kernel/kthread.c:327
       ret_from_fork+0x1f/0x30

-> #0 ((wq_completion)loop1){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3063 [inline]
       check_prevs_add kernel/locking/lockdep.c:3186 [inline]
       validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3801
       __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5027
       lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
       flush_workqueue+0x18e/0x16b0 kernel/workqueue.c:2818
       drain_workqueue+0xc3/0x3a0 kernel/workqueue.c:2983
       destroy_workqueue+0x7d/0xed0 kernel/workqueue.c:4420
       __loop_clr_fd+0x1ec/0x9b0 drivers/block/loop.c:1124
       blkdev_put+0x5a7/0x7a0
       kill_f2fs_super+0x2f9/0x3c0 fs/f2fs/super.c:4478
       deactivate_locked_super+0xa7/0xf0 fs/super.c:335
       cleanup_mnt+0x462/0x510 fs/namespace.c:1137
       task_work_run+0x146/0x1c0 kernel/task_work.c:164
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
       exit_to_user_mode_prepare+0x209/0x220 kernel/entry/common.c:207
       __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
       syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300
       do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
  (wq_completion)loop1 --> &disk->open_mutex --> &lo->lo_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&lo->lo_mutex);
                               lock(&disk->open_mutex);
                               lock(&lo->lo_mutex);
  lock((wq_completion)loop1);

 *** DEADLOCK ***

2 locks held by syz-executor.1/9709:
 #0: ffff88801af6d918 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf8/0x7a0 block/bdev.c:915
 #1: ffff88801af69360 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x6d/0x9b0 drivers/block/loop.c:1106

stack backtrace:
CPU: 0 PID: 9709 Comm: syz-executor.1 Not tainted 5.16.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
 check_noncircular+0x2f9/0x3b0 kernel/locking/lockdep.c:2143
 check_prev_add kernel/locking/lockdep.c:3063 [inline]
 check_prevs_add kernel/locking/lockdep.c:3186 [inline]
 validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3801
 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5027
 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637
 flush_workqueue+0x18e/0x16b0 kernel/workqueue.c:2818
 drain_workqueue+0xc3/0x3a0 kernel/workqueue.c:2983
 destroy_workqueue+0x7d/0xed0 kernel/workqueue.c:4420
 __loop_clr_fd+0x1ec/0x9b0 drivers/block/loop.c:1124
 blkdev_put+0x5a7/0x7a0
 kill_f2fs_super+0x2f9/0x3c0 fs/f2fs/super.c:4478
 deactivate_locked_super+0xa7/0xf0 fs/super.c:335
 cleanup_mnt+0x462/0x510 fs/namespace.c:1137
 task_work_run+0x146/0x1c0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
 exit_to_user_mode_prepare+0x209/0x220 kernel/entry/common.c:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300
 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f9e9c7e2307
Code: ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff93da3588 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f9e9c7e2307
RDX: 00007fff93da3659 RSI: 000000000000000a RDI: 00007fff93da3650
RBP: 00007fff93da3650 R08: 00000000ffffffff R09: 00007fff93da3420
R10: 00005555566608b3 R11: 0000000000000246 R12: 00007f9e9c83a172
R13: 00007fff93da4710 R14: 0000555556660810 R15: 00007fff93da4750
 </TASK>