bisecting fixing commit since f79dc86058bc0c8317eea2a0f968382c6ffb0cfb building syzkaller on 65a7a8540d29e72622fca06522587f7e66539fd3 testing commit f79dc86058bc0c8317eea2a0f968382c6ffb0cfb with gcc (GCC) 8.4.1 20210217 kernel signature: f9e6ee48aa61852b1ad4d22a86d51d0ee6c1d00ed1e1a02efe90f4efe88d7788 run #0: crashed: INFO: task hung in __get_super run #1: crashed: INFO: task hung in __blkdev_get run #2: crashed: INFO: task hung in __blkdev_get run #3: crashed: INFO: task hung in lo_ioctl run #4: crashed: INFO: task hung in __get_super run #5: crashed: INFO: task hung in lo_ioctl run #6: crashed: INFO: task hung in lo_ioctl run #7: crashed: INFO: task hung in __get_super run #8: crashed: INFO: task hung in lo_ioctl run #9: crashed: INFO: task hung in lo_ioctl run #10: crashed: INFO: task hung in __get_super run #11: crashed: INFO: task hung in lo_ioctl run #12: crashed: INFO: task hung in __blkdev_get run #13: crashed: INFO: task hung in lo_ioctl run #14: crashed: INFO: task hung in __get_super run #15: crashed: INFO: task hung in __blkdev_get run #16: crashed: INFO: task hung in __get_super run #17: crashed: INFO: task hung in __blkdev_get run #18: crashed: INFO: task hung in __blkdev_get run #19: crashed: INFO: task hung in lo_ioctl testing current HEAD cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 testing commit cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 with gcc (GCC) 8.4.1 20210217 kernel signature: 95735e58615cdac37e05f780a9606b4f2cd205d5b65d3ef11cc2bf8332e45858 run #0: crashed: INFO: task hung in __blkdev_get run #1: crashed: INFO: task hung in lo_ioctl run #2: crashed: INFO: task hung in __get_super run #3: crashed: INFO: task hung in lo_ioctl run #4: crashed: INFO: task hung in __get_super run #5: crashed: INFO: task hung in lo_ioctl run #6: crashed: INFO: task hung in __get_super run #7: crashed: INFO: task hung in __blkdev_get run #8: crashed: INFO: task hung in __get_super run #9: crashed: INFO: task hung in __blkdev_get revisions tested: 2, total time: 29m9.002070787s (build: 14m41.78254953s, test: 14m0.975841185s) the crash still happens on HEAD commit msg: Linux 4.14.231 crash: INFO: task hung in __blkdev_get Bluetooth: hci0 command 0x0406 tx timeout Bluetooth: hci5 command 0x0406 tx timeout Bluetooth: hci4 command 0x0406 tx timeout Bluetooth: hci1 command 0x0406 tx timeout Bluetooth: hci3 command 0x0406 tx timeout INFO: task systemd-udevd:4621 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. systemd-udevd D25480 4621 1 0x00000104 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x519/0x1490 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 blkdev_get+0x265/0x890 fs/block_dev.c:1611 blkdev_open+0x19f/0x200 fs/block_dev.c:1772 do_dentry_open+0x3e4/0xde0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xb6f/0x2760 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1d0/0x350 fs/open.c:1081 SYSC_open fs/open.c:1099 [inline] SyS_open+0x19/0x20 fs/open.c:1094 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fa9b0280840 RSP: 002b:00007ffdbbb6b378 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007ffdbbb6b430 RCX: 00007fa9b0280840 RDX: 0000562100945fe3 RSI: 00000000000a0800 RDI: 0000562101a8c8e0 RBP: 0000000000000000 R08: 0000562100945670 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdbbb6b520 R13: 0000562101a7b010 R14: 0000562101a8c0a0 R15: 00007ffdbbb6b3f0 INFO: task syz-executor.5:9870 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28936 9870 8312 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x1fb/0x390 kernel/locking/rwsem-xadd.c:309 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:66 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 __get_super.part.2+0x190/0x260 fs/super.c:678 __get_super include/linux/spinlock.h:317 [inline] get_super+0x23/0x30 fs/super.c:707 fsync_bdev+0x13/0xb0 fs/block_dev.c:495 invalidate_partition+0x1f/0x40 block/genhd.c:1509 drop_partitions block/partition-generic.c:442 [inline] rescan_partitions+0xac/0x8c0 block/partition-generic.c:515 __blkdev_reread_part+0x12a/0x190 block/ioctl.c:173 blkdev_reread_part+0x20/0x40 block/ioctl.c:193 loop_reread_partitions+0x5d/0x70 drivers/block/loop.c:624 loop_set_status+0xb04/0x1070 drivers/block/loop.c:1193 loop_set_status64+0x83/0xc0 drivers/block/loop.c:1311 lo_ioctl+0x53e/0x1c30 drivers/block/loop.c:1441 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x7c0/0x1760 block/ioctl.c:594 block_ioctl+0xd7/0x130 fs/block_dev.c:1893 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4658c7 RSP: 002b:00007f24c7a02ef8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f24c7a02f40 RCX: 00000000004658c7 RDX: 00007f24c7a03050 RSI: 0000000000004c04 RDI: 0000000000000004 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007f24c7a03050 R13: 00007ffc0d3cb66f R14: 00007f24c7a03300 R15: 0000000000022000 INFO: task syz-executor.0:9834 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D27512 9834 8309 0x80000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x519/0x1490 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_ioctl+0x8a/0x1c30 drivers/block/loop.c:1414 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x7c0/0x1760 block/ioctl.c:594 ioctl_by_bdev+0x95/0x110 fs/block_dev.c:2078 udf_get_last_block+0x91/0x180 fs/udf/lowlevel.c:59 udf_load_vrs+0x469/0xa00 fs/udf/super.c:1971 udf_fill_super+0x6c4/0x14f0 fs/udf/super.c:2170 mount_bdev+0x26f/0x330 fs/super.c:1134 udf_mount+0x10/0x20 fs/udf/super.c:132 mount_fs+0x7f/0x270 fs/super.c:1237 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x352/0x2af0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb1/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x465b09 RSP: 002b:00007ff4f1020188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09 RDX: 0000000020000040 RSI: 0000000020000280 RDI: 00000000200004c0 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffe28740e9f R14: 00007ff4f1020300 R15: 0000000000022000 INFO: task syz-executor.0:9842 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D26904 9842 8309 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x519/0x1490 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 blkdev_get+0x417/0x890 fs/block_dev.c:1611 blkdev_get_by_path+0x71/0xb0 fs/block_dev.c:1692 mount_bdev+0x43/0x330 fs/super.c:1092 udf_mount+0x10/0x20 fs/udf/super.c:132 mount_fs+0x7f/0x270 fs/super.c:1237 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x352/0x2af0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb1/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x465b09 RSP: 002b:00007ff4f0fff188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465b09 RDX: 0000000020000040 RSI: 0000000020000280 RDI: 00000000200004c0 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008 R13: 00007ffe28740e9f R14: 00007ff4f0fff300 R15: 0000000000022000 INFO: task syz-executor.1:9848 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28560 9848 8313 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x1fb/0x390 kernel/locking/rwsem-xadd.c:309 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:66 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 __get_super.part.2+0x190/0x260 fs/super.c:678 __get_super include/linux/spinlock.h:317 [inline] get_super+0x23/0x30 fs/super.c:707 fsync_bdev+0x13/0xb0 fs/block_dev.c:495 invalidate_partition+0x1f/0x40 block/genhd.c:1509 drop_partitions block/partition-generic.c:442 [inline] rescan_partitions+0xac/0x8c0 block/partition-generic.c:515 __blkdev_reread_part+0x12a/0x190 block/ioctl.c:173 blkdev_reread_part+0x20/0x40 block/ioctl.c:193 loop_reread_partitions+0x5d/0x70 drivers/block/loop.c:624 loop_set_status+0xb04/0x1070 drivers/block/loop.c:1193 loop_set_status64+0x83/0xc0 drivers/block/loop.c:1311 lo_ioctl+0x53e/0x1c30 drivers/block/loop.c:1441 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x7c0/0x1760 block/ioctl.c:594 block_ioctl+0xd7/0x130 fs/block_dev.c:1893 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4658c7 RSP: 002b:00007ff589130ef8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ff589130f40 RCX: 00000000004658c7 RDX: 00007ff589131050 RSI: 0000000000004c04 RDI: 0000000000000004 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007ff589131050 R13: 00007ffeef28601f R14: 00007ff589131300 R15: 0000000000022000 INFO: task syz-executor.1:9880 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28904 9880 8313 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x519/0x1490 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 blkdev_get+0x265/0x890 fs/block_dev.c:1611 blkdev_open+0x19f/0x200 fs/block_dev.c:1772 do_dentry_open+0x3e4/0xde0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xb6f/0x2760 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1d0/0x350 fs/open.c:1081 SYSC_openat fs/open.c:1108 [inline] SyS_openat+0xf/0x20 fs/open.c:1102 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4190f4 RSP: 002b:00007ff58910fe20 EFLAGS: 00000293 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000004bf6b0 RCX: 00000000004190f4 RDX: 0000000000000002 RSI: 00007ff58910ff40 RDI: 00000000ffffff9c RBP: 00007ff58910ff40 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002 R13: 0000000000000003 R14: 00000000200002d8 R15: 0000000000000001 INFO: task syz-executor.2:9865 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27512 9865 8306 0x80000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x519/0x1490 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_ioctl+0x8a/0x1c30 drivers/block/loop.c:1414 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x7c0/0x1760 block/ioctl.c:594 ioctl_by_bdev+0x95/0x110 fs/block_dev.c:2078 udf_get_last_block+0x91/0x180 fs/udf/lowlevel.c:59 udf_load_vrs+0x469/0xa00 fs/udf/super.c:1971 udf_fill_super+0x6c4/0x14f0 fs/udf/super.c:2170 mount_bdev+0x26f/0x330 fs/super.c:1134 udf_mount+0x10/0x20 fs/udf/super.c:132 mount_fs+0x7f/0x270 fs/super.c:1237 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x352/0x2af0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb1/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x465b09 RSP: 002b:00007f2e00db8188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09 RDX: 0000000020000040 RSI: 0000000020000280 RDI: 00000000200004c0 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffc9ddec7bf R14: 00007f2e00db8300 R15: 0000000000022000 INFO: task syz-executor.2:9866 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D26904 9866 8306 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x519/0x1490 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 blkdev_get+0x417/0x890 fs/block_dev.c:1611 blkdev_get_by_path+0x71/0xb0 fs/block_dev.c:1692 mount_bdev+0x43/0x330 fs/super.c:1092 udf_mount+0x10/0x20 fs/udf/super.c:132 mount_fs+0x7f/0x270 fs/super.c:1237 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x352/0x2af0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb1/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x465b09 RSP: 002b:00007f2e00d97188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465b09 RDX: 0000000020000040 RSI: 0000000020000280 RDI: 00000000200004c0 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008 R13: 00007ffc9ddec7bf R14: 00007f2e00d97300 R15: 0000000000022000 Showing all locks held in the system: 1 lock held by khungtaskd/1532: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4548 1 lock held by systemd-udevd/4621: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 3 locks held by syz-executor.5/9870: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [] lo_ioctl+0x8a/0x1c30 drivers/block/loop.c:1414 #1: (&bdev->bd_mutex){+.+.}, at: [] blkdev_reread_part+0x18/0x40 block/ioctl.c:192 #2: (&type->s_umount_key#49){++++}, at: [] __get_super.part.2+0x190/0x260 fs/super.c:678 2 locks held by syz-executor.0/9834: #0: (&type->s_umount_key#48/1){+.+.}, at: [] alloc_super fs/super.c:251 [inline] #0: (&type->s_umount_key#48/1){+.+.}, at: [] sget_userns+0x429/0xb40 fs/super.c:516 #1: (&lo->lo_ctl_mutex/1){+.+.}, at: [] lo_ioctl+0x8a/0x1c30 drivers/block/loop.c:1414 1 lock held by syz-executor.0/9842: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 3 locks held by syz-executor.1/9848: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [] lo_ioctl+0x8a/0x1c30 drivers/block/loop.c:1414 #1: (&bdev->bd_mutex){+.+.}, at: [] blkdev_reread_part+0x18/0x40 block/ioctl.c:192 #2: (&type->s_umount_key#49){++++}, at: [] __get_super.part.2+0x190/0x260 fs/super.c:678 1 lock held by syz-executor.1/9880: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 2 locks held by syz-executor.2/9865: #0: (&type->s_umount_key#48/1){+.+.}, at: [] alloc_super fs/super.c:251 [inline] #0: (&type->s_umount_key#48/1){+.+.}, at: [] sget_userns+0x429/0xb40 fs/super.c:516 #1: (&lo->lo_ctl_mutex/1){+.+.}, at: [] lo_ioctl+0x8a/0x1c30 drivers/block/loop.c:1414 1 lock held by syz-executor.2/9866: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x185/0xff0 fs/block_dev.c:1455 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1532 Comm: khungtaskd Not tainted 4.14.231-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1e7 lib/dump_stack.c:58 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf6/0x120 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x51b/0xa70 kernel/hung_task.c:274 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff87359b32