====================================================== WARNING: possible circular locking dependency detected 5.15.173-syzkaller #0 Not tainted ------------------------------------------------------ syz.5.638/6866 is trying to acquire lock: ffff0000d8c6a138 ((wq_completion)loop5){+.+.}-{0:0}, at: flush_workqueue+0x120/0x11c4 kernel/workqueue.c:2830 but task is already holding lock: ffff0000cbeaf468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa8/0x9b8 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+0x194/0x2154 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_killable_nested+0xa4/0xf8 kernel/locking/mutex.c:758 lo_open+0x6c/0x14c drivers/block/loop.c:2055 blkdev_get_whole+0x94/0x344 block/bdev.c:669 blkdev_get_by_dev+0x238/0x89c block/bdev.c:824 blkdev_open+0x10c/0x274 block/fops.c:463 do_dentry_open+0x780/0xed8 fs/open.c:826 vfs_open+0x7c/0x90 fs/open.c:956 do_open fs/namei.c:3608 [inline] path_openat+0x1ea0/0x26cc fs/namei.c:3742 do_filp_open+0x1a8/0x3b4 fs/namei.c:3769 do_sys_openat2+0x128/0x3e0 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] __arm64_sys_openat+0x1f0/0x240 fs/open.c:1280 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #6 (&disk->open_mutex){+.+.}-{3:3}: __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743 blkdev_get_by_dev+0x12c/0x89c block/bdev.c:817 swsusp_check+0xb8/0x2dc kernel/power/swap.c:1526 software_resume+0xe8/0x410 kernel/power/hibernate.c:977 resume_store+0xe4/0x12c kernel/power/hibernate.c:1179 kobj_attr_store+0x6c/0x90 lib/kobject.c:864 sysfs_kf_write+0x200/0x280 fs/sysfs/file.c:139 kernfs_fop_write_iter+0x334/0x48c fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x884/0xb44 fs/read_write.c:594 ksys_write+0x15c/0x26c fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #5 (system_transition_mutex/1){+.+.}-{3:3}: __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743 software_resume+0x9c/0x410 kernel/power/hibernate.c:932 resume_store+0xe4/0x12c kernel/power/hibernate.c:1179 kobj_attr_store+0x6c/0x90 lib/kobject.c:864 sysfs_kf_write+0x200/0x280 fs/sysfs/file.c:139 kernfs_fop_write_iter+0x334/0x48c fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x884/0xb44 fs/read_write.c:594 ksys_write+0x15c/0x26c fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #4 (&of->mutex){+.+.}-{3:3}: __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743 kernfs_seq_start+0x58/0x3a0 fs/kernfs/file.c:112 seq_read_iter+0x378/0xc44 fs/seq_file.c:225 kernfs_fop_read_iter+0x140/0x50c fs/kernfs/file.c:241 call_read_iter include/linux/fs.h:2168 [inline] new_sync_read fs/read_write.c:404 [inline] vfs_read+0x874/0xb18 fs/read_write.c:485 ksys_read+0x15c/0x26c fs/read_write.c:623 __do_sys_read fs/read_write.c:633 [inline] __se_sys_read fs/read_write.c:631 [inline] __arm64_sys_read+0x7c/0x90 fs/read_write.c:631 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #3 (&p->lock){+.+.}-{3:3}: __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743 seq_read_iter+0xac/0xc44 fs/seq_file.c:182 call_read_iter include/linux/fs.h:2168 [inline] generic_file_splice_read+0x3a0/0x60c fs/splice.c:311 do_splice_to fs/splice.c:796 [inline] splice_direct_to_actor+0x354/0x9a0 fs/splice.c:870 do_splice_direct+0x1f4/0x334 fs/splice.c:979 do_sendfile+0x4c0/0xcb0 fs/read_write.c:1249 __do_sys_sendfile64 fs/read_write.c:1317 [inline] __se_sys_sendfile64 fs/read_write.c:1303 [inline] __arm64_sys_sendfile64+0x160/0x408 fs/read_write.c:1303 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #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+0x21c/0xb4c 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+0x1f24/0x2798 drivers/block/loop.c:2274 loop_workfn+0x54/0x68 drivers/block/loop.c:2298 process_one_work+0x790/0x11b8 kernel/workqueue.c:2310 worker_thread+0x910/0x1034 kernel/workqueue.c:2457 kthread+0x37c/0x45c kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870 -> #1 ((work_completion)(&worker->work)){+.+.}-{0:0}: process_one_work+0x6d4/0x11b8 kernel/workqueue.c:2286 worker_thread+0x910/0x1034 kernel/workqueue.c:2457 kthread+0x37c/0x45c kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870 -> #0 ((wq_completion)loop5){+.+.}-{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+0x32d4/0x7638 kernel/locking/lockdep.c:5012 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623 flush_workqueue+0x14c/0x11c4 kernel/workqueue.c:2830 drain_workqueue+0xb8/0x32c kernel/workqueue.c:2995 destroy_workqueue+0x80/0xa34 kernel/workqueue.c:4439 __loop_clr_fd+0x1c0/0x9b8 drivers/block/loop.c:1383 loop_clr_fd drivers/block/loop.c:1509 [inline] lo_ioctl+0xe74/0x20d0 drivers/block/loop.c:1865 blkdev_ioctl+0x3d8/0xbd0 block/ioctl.c:604 block_ioctl+0xa8/0x114 block/fops.c:493 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Chain exists of: (wq_completion)loop5 --> &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)loop5); *** DEADLOCK *** 1 lock held by syz.5.638/6866: #0: ffff0000cbeaf468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa8/0x9b8 drivers/block/loop.c:1365 stack backtrace: CPU: 1 PID: 6866 Comm: syz.5.638 Not tainted 5.15.173-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Call trace: dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011 check_noncircular+0x2cc/0x378 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+0x32d4/0x7638 kernel/locking/lockdep.c:5012 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623 flush_workqueue+0x14c/0x11c4 kernel/workqueue.c:2830 drain_workqueue+0xb8/0x32c kernel/workqueue.c:2995 destroy_workqueue+0x80/0xa34 kernel/workqueue.c:4439 __loop_clr_fd+0x1c0/0x9b8 drivers/block/loop.c:1383 loop_clr_fd drivers/block/loop.c:1509 [inline] lo_ioctl+0xe74/0x20d0 drivers/block/loop.c:1865 blkdev_ioctl+0x3d8/0xbd0 block/ioctl.c:604 block_ioctl+0xa8/0x114 block/fops.c:493 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584