====================================================== WARNING: possible circular locking dependency detected 5.15.0-syzkaller #0 Not tainted ------------------------------------------------------ systemd-udevd/32363 is trying to acquire lock: ffff88807912c138 ((wq_completion)loop3){+.+.}-{0:0}, at: flush_workqueue+0x172/0x16b0 kernel/workqueue.c:2818 but task is already holding lock: ffff888147390b60 (&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: -> #8 (&lo->lo_mutex){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5640 __mutex_lock_common+0x1d5/0x2590 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+0x298/0xb80 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_open fs/open.c:1236 [inline] __se_sys_open fs/open.c:1232 [inline] __x64_sys_open+0x221/0x270 fs/open.c:1232 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 -> #7 (&disk->open_mutex){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5640 __mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607 __mutex_lock kernel/locking/mutex.c:740 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792 bd_register_pending_holders+0x32/0x370 block/holder.c:161 device_add_disk+0x4e5/0xe50 block/genhd.c:478 add_disk include/linux/genhd.h:212 [inline] loop_add+0x5c4/0x8b0 drivers/block/loop.c:2053 blk_request_module+0x19d/0x1c0 block/genhd.c:683 blkdev_get_no_open+0x37/0x180 block/bdev.c:742 blkdev_get_by_dev+0x84/0xb80 block/bdev.c:806 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_open fs/open.c:1236 [inline] __se_sys_open fs/open.c:1232 [inline] __x64_sys_open+0x221/0x270 fs/open.c:1232 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 (major_names_lock){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5640 __mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:607 __mutex_lock kernel/locking/mutex.c:740 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:792 blk_request_module+0x2f/0x1c0 block/genhd.c:680 blkdev_get_no_open+0x37/0x180 block/bdev.c:742 blkdev_get_by_dev+0x84/0xb80 block/bdev.c:806 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:5640 __mutex_lock_common+0x1d5/0x2590 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:5640 __mutex_lock_common+0x1d5/0x2590 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:5640 __mutex_lock_common+0x1d5/0x2590 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:5640 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:3009 [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:5640 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)loop3){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3066 [inline] check_prevs_add kernel/locking/lockdep.c:3189 [inline] validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3804 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5030 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5640 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_whole block/bdev.c:694 [inline] blkdev_put+0x477/0x7b0 block/bdev.c:956 blkdev_close+0x58/0x80 block/fops.c:515 __fput+0x3fc/0x870 fs/file_table.c:280 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)loop3 --> &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)loop3); *** DEADLOCK *** 2 locks held by systemd-udevd/32363: #0: ffff88801a8d4118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfa/0x7b0 block/bdev.c:914 #1: ffff888147390b60 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x6d/0x9b0 drivers/block/loop.c:1106 stack backtrace: CPU: 0 PID: 32363 Comm: systemd-udevd Not tainted 5.15.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __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:2146 check_prev_add kernel/locking/lockdep.c:3066 [inline] check_prevs_add kernel/locking/lockdep.c:3189 [inline] validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3804 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5030 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5640 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_whole block/bdev.c:694 [inline] blkdev_put+0x477/0x7b0 block/bdev.c:956 blkdev_close+0x58/0x80 block/fops.c:515 __fput+0x3fc/0x870 fs/file_table.c:280 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: 0033:0x7fa38db4c270 Code: 73 01 c3 48 8b 0d 38 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c1 20 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24 RSP: 002b:00007ffc87bf1808 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fa38db4c270 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 00007fa38ea06710 R08: 00005612d6bfe3f0 R09: 00005612d6c04f00 R10: 00007fa38ea068c0 R11: 0000000000000246 R12: 0000000000000000 R13: 00005612d6bffc00 R14: 0000000000000003 R15: 000000000000000e