====================================================== WARNING: possible circular locking dependency detected 5.15.98-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/3624 is trying to acquire lock: ffff8880788c1138 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x154/0x1610 kernel/workqueue.c:2826 but task is already holding lock: ffff88807d780468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1348 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #7 (&lo->lo_mutex){+.+.}-{3:3}: lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 __mutex_lock_common+0x1da/0x25a0 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+0x68/0x100 drivers/block/loop.c:2038 blkdev_get_whole+0x94/0x390 block/bdev.c:669 blkdev_get_by_dev+0x2b2/0xa50 block/bdev.c:824 blkdev_open+0x138/0x2d0 block/fops.c:448 do_dentry_open+0x807/0xfb0 fs/open.c:826 do_open fs/namei.c:3480 [inline] path_openat+0x26c3/0x2ed0 fs/namei.c:3615 do_filp_open+0x21c/0x460 fs/namei.c:3642 do_sys_openat2+0x13b/0x500 fs/open.c:1211 do_sys_open fs/open.c:1227 [inline] __do_sys_openat fs/open.c:1243 [inline] __se_sys_openat fs/open.c:1238 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1238 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x61/0xcb -> #6 (&disk->open_mutex){+.+.}-{3:3}: lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 blkdev_get_by_dev+0x14d/0xa50 block/bdev.c:817 swsusp_check+0xb1/0x2c0 kernel/power/swap.c:1526 software_resume+0xc6/0x3c0 kernel/power/hibernate.c:977 resume_store+0xe3/0x130 kernel/power/hibernate.c:1179 kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2101 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacf/0xe50 fs/read_write.c:594 ksys_write+0x1a2/0x2c0 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x61/0xcb -> #5 (system_transition_mutex/1){+.+.}-{3:3}: lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 __mutex_lock_common+0x1da/0x25a0 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/0x3c0 kernel/power/hibernate.c:932 resume_store+0xe3/0x130 kernel/power/hibernate.c:1179 kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2101 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacf/0xe50 fs/read_write.c:594 ksys_write+0x1a2/0x2c0 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x61/0xcb -> #4 (&of->mutex){+.+.}-{3:3}: lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 __mutex_lock_common+0x1da/0x25a0 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+0x50/0x3b0 fs/kernfs/file.c:112 seq_read_iter+0x3d0/0xd10 fs/seq_file.c:225 call_read_iter include/linux/fs.h:2095 [inline] new_sync_read fs/read_write.c:404 [inline] vfs_read+0xa9f/0xe10 fs/read_write.c:485 ksys_read+0x1a2/0x2c0 fs/read_write.c:623 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x61/0xcb -> #3 (&p->lock){+.+.}-{3:3}: lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 __mutex_lock_common+0x1da/0x25a0 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+0xae/0xd10 fs/seq_file.c:182 proc_reg_read_iter+0x1b7/0x280 fs/proc/inode.c:300 call_read_iter include/linux/fs.h:2095 [inline] generic_file_splice_read+0x4ad/0x790 fs/splice.c:311 do_splice_to fs/splice.c:796 [inline] splice_direct_to_actor+0x448/0xc10 fs/splice.c:870 do_splice_direct+0x285/0x3d0 fs/splice.c:979 do_sendfile+0x625/0xff0 fs/read_write.c:1249 __do_sys_sendfile64 fs/read_write.c:1317 [inline] __se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1303 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x61/0xcb -> #2 (sb_writers#3){.+.+}-{0:0}: lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1742 [inline] sb_start_write include/linux/fs.h:1812 [inline] file_start_write include/linux/fs.h:2964 [inline] lo_write_bvec+0x1a3/0x710 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:2208 [inline] loop_process_work+0x209c/0x2b30 drivers/block/loop.c:2248 process_one_work+0x8e6/0x1230 kernel/workqueue.c:2306 worker_thread+0xaca/0x1280 kernel/workqueue.c:2453 kthread+0x3f6/0x4f0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 :298 -> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}: lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 process_one_work+0x7ee/0x1230 kernel/workqueue.c:2282 worker_thread+0xaca/0x1280 kernel/workqueue.c:2453 kthread+0x3f6/0x4f0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 :298 -> #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+0x1646/0x58b0 kernel/locking/lockdep.c:3787 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011 lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 flush_workqueue+0x170/0x1610 kernel/workqueue.c:2826 drain_workqueue+0xc5/0x390 kernel/workqueue.c:2991 destroy_workqueue+0x7b/0xae0 kernel/workqueue.c:4426 __loop_clr_fd+0x241/0xbe0 drivers/block/loop.c:1366 blkdev_put_whole block/bdev.c:692 [inline] blkdev_put+0x455/0x790 block/bdev.c:954 deactivate_locked_super+0xa0/0x110 fs/super.c:335 cleanup_mnt+0x44e/0x500 fs/namespace.c:1143 task_work_run+0x129/0x1a0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:175 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x5d/0x2a0 kernel/entry/common.c:300 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x61/0xcb 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 syz-executor.0/3624: #0: ffff88807caaf918 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfb/0x790 block/bdev.c:912 #1: ffff88807d780468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1348 stack backtrace: CPU: 1 PID: 3624 Comm: syz-executor.0 Not tainted 5.15.98-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2f8/0x3b0 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+0x1646/0x58b0 kernel/locking/lockdep.c:3787 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011 lock_acquire+0x1f6/0x560 kernel/locking/lockdep.c:5622 flush_workqueue+0x170/0x1610 kernel/workqueue.c:2826 drain_workqueue+0xc5/0x390 kernel/workqueue.c:2991 destroy_workqueue+0x7b/0xae0 kernel/workqueue.c:4426 __loop_clr_fd+0x241/0xbe0 drivers/block/loop.c:1366 blkdev_put_whole block/bdev.c:692 [inline] blkdev_put+0x455/0x790 block/bdev.c:954 deactivate_locked_super+0xa0/0x110 fs/super.c:335 cleanup_mnt+0x44e/0x500 fs/namespace.c:1143 task_work_run+0x129/0x1a0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:175 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x5d/0x2a0 kernel/entry/common.c:300 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f987922b567 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe19b87f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f987922b567 RDX: 00007ffe19b8802c RSI: 000000000000000a RDI: 00007ffe19b88020 RBP: 00007ffe19b88020 R08: 00000000ffffffff R09: 00007ffe19b87df0 R10: 000055555740a873 R11: 0000000000000246 R12: 00007f9879284b24 R13: 00007ffe19b890e0 R14: 000055555740a810 R15: 00007ffe19b89120