====================================================== WARNING: possible circular locking dependency detected 5.15.185-syzkaller #0 Not tainted ------------------------------------------------------ kworker/u4:5/4226 is trying to acquire lock: ffff88802279fe80 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182 but task is already holding lock: ffffc900031cfd00 ((work_completion)(&worker->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #8 ((work_completion)(&worker->work)){+.+.}-{0:0}: process_one_work+0x7bf/0x1000 kernel/workqueue.c:2286 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #7 ((wq_completion)loop0){+.+.}-{0:0}: flush_workqueue+0x142/0x1380 kernel/workqueue.c:2830 drain_workqueue+0xcf/0x380 kernel/workqueue.c:2995 destroy_workqueue+0x7b/0xb20 kernel/workqueue.c:4439 __loop_clr_fd+0x234/0xb90 drivers/block/loop.c:1384 blkdev_put_whole block/bdev.c:692 [inline] blkdev_put+0x53f/0x7d0 block/bdev.c:957 deactivate_locked_super+0x93/0xf0 fs/super.c:335 cleanup_mnt+0x418/0x4d0 fs/namespace.c:1139 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #6 (&lo->lo_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_killable_nested+0x17/0x20 kernel/locking/mutex.c:758 lo_open+0x6a/0x100 drivers/block/loop.c:2056 blkdev_get_whole+0x90/0x390 block/bdev.c:669 blkdev_get_by_dev+0x2d0/0xa60 block/bdev.c:827 blkdev_open+0x12d/0x2c0 block/fops.c:466 do_dentry_open+0x7ff/0xf80 fs/open.c:826 do_open fs/namei.c:3608 [inline] path_openat+0x2682/0x2f30 fs/namei.c:3742 do_filp_open+0x1b3/0x3e0 fs/namei.c:3769 do_sys_openat2+0x142/0x4a0 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+0x135/0x160 fs/open.c:1280 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #5 (&disk->open_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 bd_register_pending_holders+0x33/0x310 block/holder.c:161 device_add_disk+0x5a7/0xd40 block/genhd.c:486 add_disk include/linux/genhd.h:200 [inline] md_alloc+0x809/0xc00 drivers/md/md.c:5782 blk_probe_dev block/genhd.c:685 [inline] blk_request_module+0x26e/0x290 block/genhd.c:-1 blkdev_get_no_open+0x38/0x1d0 block/bdev.c:740 blkdev_get_by_dev+0x77/0xa60 block/bdev.c:807 swsusp_check+0x9b/0x2a0 kernel/power/swap.c:1526 software_resume+0xc6/0x3b0 kernel/power/hibernate.c:982 resume_store+0xe4/0x130 kernel/power/hibernate.c:1184 kernfs_fop_write_iter+0x379/0x4c0 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2172 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x712/0xd00 fs/read_write.c:594 ksys_write+0x14d/0x250 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #4 (disks_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 md_alloc+0x48/0xc00 drivers/md/md.c:5723 blk_probe_dev block/genhd.c:685 [inline] blk_request_module+0x26e/0x290 block/genhd.c:-1 blkdev_get_no_open+0x38/0x1d0 block/bdev.c:740 blkdev_get_by_dev+0x77/0xa60 block/bdev.c:807 swsusp_check+0x9b/0x2a0 kernel/power/swap.c:1526 software_resume+0xc6/0x3b0 kernel/power/hibernate.c:982 resume_store+0xe4/0x130 kernel/power/hibernate.c:1184 kernfs_fop_write_iter+0x379/0x4c0 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2172 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x712/0xd00 fs/read_write.c:594 ksys_write+0x14d/0x250 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #3 (major_names_lock){+.+.}-{3:3}: __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 blk_probe_dev block/genhd.c:682 [inline] blk_request_module+0x31/0x290 block/genhd.c:698 blkdev_get_no_open+0x38/0x1d0 block/bdev.c:740 blkdev_get_by_dev+0x77/0xa60 block/bdev.c:807 swsusp_check+0x9b/0x2a0 kernel/power/swap.c:1526 software_resume+0xc6/0x3b0 kernel/power/hibernate.c:982 resume_store+0xe4/0x130 kernel/power/hibernate.c:1184 kernfs_fop_write_iter+0x379/0x4c0 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2172 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x712/0xd00 fs/read_write.c:594 ksys_write+0x14d/0x250 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #2 (system_transition_mutex/1){+.+.}-{3:3}: __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 software_resume+0x7c/0x3b0 kernel/power/hibernate.c:937 resume_store+0xe4/0x130 kernel/power/hibernate.c:1184 kernfs_fop_write_iter+0x379/0x4c0 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2172 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x712/0xd00 fs/read_write.c:594 ksys_write+0x14d/0x250 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #1 (&of->mutex){+.+.}-{3:3}: __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112 seq_read_iter+0x3c4/0xd50 fs/seq_file.c:225 call_read_iter include/linux/fs.h:2166 [inline] new_sync_read fs/read_write.c:404 [inline] vfs_read+0x725/0xcf0 fs/read_write.c:485 ksys_read+0x14d/0x250 fs/read_write.c:623 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #0 (&p->lock){+.+.}-{3:3}: 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 seq_read_iter+0xad/0xd50 fs/seq_file.c:182 do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1 do_iter_read+0x20b/0x7c0 fs/read_write.c:790 lo_read_simple drivers/block/loop.c:392 [inline] do_req_filebacked drivers/block/loop.c:663 [inline] loop_handle_cmd drivers/block/loop.c:2235 [inline] loop_process_work+0x18dc/0x2480 drivers/block/loop.c:2275 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 other info that might help us debug this: Chain exists of: &p->lock --> (wq_completion)loop0 --> (work_completion)(&worker->work) Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&worker->work)); lock((wq_completion)loop0); lock((work_completion)(&worker->work)); lock(&p->lock); *** DEADLOCK *** 2 locks held by kworker/u4:5/4226: #0: ffff88807de77938 ((wq_completion)loop9){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1 #1: ffffc900031cfd00 ((work_completion)(&worker->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285 stack backtrace: CPU: 0 PID: 4226 Comm: kworker/u4:5 Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: loop9 loop_workfn Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 check_noncircular+0x274/0x310 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 seq_read_iter+0xad/0xd50 fs/seq_file.c:182 do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1 do_iter_read+0x20b/0x7c0 fs/read_write.c:790 lo_read_simple drivers/block/loop.c:392 [inline] do_req_filebacked drivers/block/loop.c:663 [inline] loop_handle_cmd drivers/block/loop.c:2235 [inline] loop_process_work+0x18dc/0x2480 drivers/block/loop.c:2275 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287