======================================================
WARNING: possible circular locking dependency detected
5.15.175-syzkaller #0 Not tainted
------------------------------------------------------
udevd/3564 is trying to acquire lock:
ffff88811b528d38 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x86/0x6b0 kernel/workqueue.c:2827

but task is already holding lock:
ffff88810a1a7468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x60/0x8c0 drivers/block/loop.c:1365

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (&lo->lo_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:596 [inline]
       __mutex_lock+0x60/0x660 kernel/locking/mutex.c:729
       lo_open+0x2e/0x90 drivers/block/loop.c:2055
       blkdev_get_whole+0x36/0x110 block/bdev.c:669
       blkdev_get_by_dev+0x1b3/0x480 block/bdev.c:824
       blkdev_open+0xc9/0x140 block/fops.c:463
       do_dentry_open+0x311/0x660 fs/open.c:826
       do_open fs/namei.c:3608 [inline]
       path_openat+0xe37/0x1370 fs/namei.c:3742
       do_filp_open+0xc1/0x1b0 fs/namei.c:3769
       do_sys_openat2+0xed/0x260 fs/open.c:1253
       do_sys_open fs/open.c:1269 [inline]
       __do_sys_openat fs/open.c:1285 [inline]
       __se_sys_openat fs/open.c:1280 [inline]
       __x64_sys_openat+0x7f/0xe0 fs/open.c:1280
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x33/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #6 (&disk->open_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:596 [inline]
       __mutex_lock+0x60/0x660 kernel/locking/mutex.c:729
       blkdev_get_by_dev+0x172/0x480 block/bdev.c:817
       swsusp_check+0x30/0x1f0 kernel/power/swap.c:1526
       software_resume.part.0+0x102/0x1f0 kernel/power/hibernate.c:977
       software_resume kernel/power/hibernate.c:86 [inline]
       resume_store+0x136/0x150 kernel/power/hibernate.c:1179
       kobj_attr_store+0x35/0x60 lib/kobject.c:864
       sysfs_kf_write+0xb4/0x100 fs/sysfs/file.c:139
       kernfs_fop_write_iter+0x1d3/0x2e0 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2174 [inline]
       new_sync_write+0x1da/0x2b0 fs/read_write.c:507
       vfs_write+0x3a8/0x560 fs/read_write.c:594
       ksys_write+0xa6/0x170 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x33/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #5 (system_transition_mutex/1){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:596 [inline]
       __mutex_lock+0x60/0x660 kernel/locking/mutex.c:729
       software_resume.part.0+0x19/0x1f0 kernel/power/hibernate.c:932
       software_resume kernel/power/hibernate.c:86 [inline]
       resume_store+0x136/0x150 kernel/power/hibernate.c:1179
       kobj_attr_store+0x35/0x60 lib/kobject.c:864
       sysfs_kf_write+0xb4/0x100 fs/sysfs/file.c:139
       kernfs_fop_write_iter+0x1d3/0x2e0 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2174 [inline]
       new_sync_write+0x1da/0x2b0 fs/read_write.c:507
       vfs_write+0x3a8/0x560 fs/read_write.c:594
       ksys_write+0xa6/0x170 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x33/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #4 (&of->mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:596 [inline]
       __mutex_lock+0x60/0x660 kernel/locking/mutex.c:729
       kernfs_seq_start+0x2a/0x110 fs/kernfs/file.c:112
       seq_read_iter+0x177/0x700 fs/seq_file.c:225
       kernfs_fop_read_iter+0x226/0x2b0 fs/kernfs/file.c:241
       call_read_iter include/linux/fs.h:2168 [inline]
       new_sync_read+0x1dd/0x2f0 fs/read_write.c:404
       vfs_read+0x1c0/0x2b0 fs/read_write.c:485
       ksys_read+0xa6/0x170 fs/read_write.c:623
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x33/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #3 (&p->lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:596 [inline]
       __mutex_lock+0x60/0x660 kernel/locking/mutex.c:729
       seq_read_iter+0x72/0x700 fs/seq_file.c:182
       call_read_iter include/linux/fs.h:2168 [inline]
       generic_file_splice_read+0x1b9/0x300 fs/splice.c:311
       do_splice_to+0xbf/0x100 fs/splice.c:796
       splice_direct_to_actor+0xe2/0x340 fs/splice.c:870
       do_splice_direct+0xee/0x150 fs/splice.c:979
       do_sendfile+0x5bf/0x9a0 fs/read_write.c:1249
       __do_sys_sendfile64 fs/read_write.c:1317 [inline]
       __se_sys_sendfile64 fs/read_write.c:1303 [inline]
       __x64_sys_sendfile64+0xf7/0x110 fs/read_write.c:1303
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x33/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (sb_writers#5){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1813 [inline]
       sb_start_write include/linux/fs.h:1883 [inline]
       file_start_write include/linux/fs.h:3044 [inline]
       lo_write_bvec+0x119/0x3a0 drivers/block/loop.c:315
       lo_write_simple drivers/block/loop.c:338 [inline]
       do_req_filebacked drivers/block/loop.c:656 [inline]
       loop_handle_cmd drivers/block/loop.c:2234 [inline]
       loop_process_work+0x626/0x12e0 drivers/block/loop.c:2274
       process_one_work+0x32a/0x680 kernel/workqueue.c:2310
       worker_thread+0x5b/0x520 kernel/workqueue.c:2457
       kthread+0x148/0x170 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
       process_one_work+0x2e8/0x680 kernel/workqueue.c:2286
       worker_thread+0x5b/0x520 kernel/workqueue.c:2457
       kthread+0x148/0x170 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x10b6/0x1a40 kernel/locking/lockdep.c:5012
       lock_acquire kernel/locking/lockdep.c:5623 [inline]
       lock_acquire+0xbb/0x290 kernel/locking/lockdep.c:5588
       flush_workqueue+0xb2/0x6b0 kernel/workqueue.c:2830
       drain_workqueue+0xed/0x1b0 kernel/workqueue.c:2995
       destroy_workqueue+0x42/0x380 kernel/workqueue.c:4439
       __loop_clr_fd+0xd9/0x8c0 drivers/block/loop.c:1383
       lo_release+0xeb/0xf0 drivers/block/loop.c:2083
       blkdev_put_whole+0x4e/0xc0 block/bdev.c:692
       blkdev_put+0x18d/0x300 block/bdev.c:954
       blkdev_close+0x26/0x30 block/fops.c:475
       __fput+0xf9/0x420 fs/file_table.c:280
       task_work_run+0x73/0xb0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:181 [inline]
       exit_to_user_mode_prepare+0x20b/0x210 kernel/entry/common.c:214
       __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
       syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:307
       do_syscall_64+0x40/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  (wq_completion)loop0 --> &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)loop0);

 *** DEADLOCK ***

2 locks held by udevd/3564:
 #0: ffff888109f70b18 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x5b/0x300 block/bdev.c:912
 #1: ffff88810a1a7468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x60/0x8c0 drivers/block/loop.c:1365

stack backtrace:
CPU: 0 PID: 3564 Comm: udevd Not tainted 5.15.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 check_noncircular+0xcc/0xe0 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x10b6/0x1a40 kernel/locking/lockdep.c:5012
 lock_acquire kernel/locking/lockdep.c:5623 [inline]
 lock_acquire+0xbb/0x290 kernel/locking/lockdep.c:5588
 flush_workqueue+0xb2/0x6b0 kernel/workqueue.c:2830
 drain_workqueue+0xed/0x1b0 kernel/workqueue.c:2995
 destroy_workqueue+0x42/0x380 kernel/workqueue.c:4439
 __loop_clr_fd+0xd9/0x8c0 drivers/block/loop.c:1383
 lo_release+0xeb/0xf0 drivers/block/loop.c:2083
 blkdev_put_whole+0x4e/0xc0 block/bdev.c:692
 blkdev_put+0x18d/0x300 block/bdev.c:954
 blkdev_close+0x26/0x30 block/fops.c:475
 __fput+0xf9/0x420 fs/file_table.c:280
 task_work_run+0x73/0xb0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:181 [inline]
 exit_to_user_mode_prepare+0x20b/0x210 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:307
 do_syscall_64+0x40/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff9cedb60a8
Code: 48 8b 05 83 9d 0d 00 64 c7 00 16 00 00 00 83 c8 ff 48 83 c4 20 5b c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 5b 48 8b 15 51 9d 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffdd635abc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007ff9cec8aae0 RCX: 00007ff9cedb60a8
RDX: 0000560e0dccf857 RSI: 00007ffdd635a3c8 RDI: 0000000000000008
RBP: 0000560b6d791490 R08: 0000000000000006 R09: 5ecd7edec439cbb5
R10: 000000000000010f R11: 0000000000000246 R12: 0000000000000002
R13: 0000560b6d777330 R14: 0000000000000008 R15: 0000560b6d764910
 </TASK>