syzbot


INFO: task hung in blkdev_get

Status: upstream: reported C repro on 2021/12/18 01:06
Reported-by: syzbot+fc641afaef76ef2729e7@syzkaller.appspotmail.com
First crash: 914d, last: 477d
Fix bisection attempts (13)
Created Duration User Patch Repo Result
2023/02/28 04:06 28m bisect fix linux-4.14.y job log (0) log
2023/01/26 08:14 25m bisect fix linux-4.14.y job log (0) log
2022/11/17 14:25 22m bisect fix linux-4.14.y job log (0) log
2022/10/18 13:46 26m bisect fix linux-4.14.y job log (0) log
2022/09/15 12:14 20m bisect fix linux-4.14.y job log (0) log
2022/08/16 11:51 22m bisect fix linux-4.14.y job log (0) log
2022/07/17 11:23 27m bisect fix linux-4.14.y job log (0) log
2022/06/17 10:56 27m bisect fix linux-4.14.y job log (0) log
2022/05/18 10:27 29m bisect fix linux-4.14.y job log (0) log
2022/04/18 09:59 27m bisect fix linux-4.14.y job log (0) log
2022/03/19 05:14 31m bisect fix linux-4.14.y job log (0) log
2022/02/16 01:32 23m bisect fix linux-4.14.y job log (0) log
2022/01/17 01:05 27m bisect fix linux-4.14.y job log (0) log

Sample crash report:
INFO: task syz-executor678:8007 blocked for more than 140 seconds.
      Not tainted 4.14.258-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor678 D27384  8007   8005 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 context_switch kernel/sched/core.c:2811 [inline] kernel/sched/core.c:3387
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 kernel/sched/core.c:3431
 bd_prepare_to_claim fs/block_dev.c:1078 [inline]
 bd_start_claiming fs/block_dev.c:1149 [inline]
 bd_prepare_to_claim fs/block_dev.c:1078 [inline] fs/block_dev.c:1604
 bd_start_claiming fs/block_dev.c:1149 [inline] fs/block_dev.c:1604
 blkdev_get+0x3ee/0x890 fs/block_dev.c:1604 fs/block_dev.c:1604
 blkdev_get_by_path+0x38/0xa0 fs/block_dev.c:1692 fs/block_dev.c:1692
 mount_bdev+0x4c/0x360 fs/super.c:1092 fs/super.c:1092
 mount_fs+0x92/0x2a0 fs/super.c:1237 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2572 [inline]
 vfs_kern_mount fs/namespace.c:1036 [inline] fs/namespace.c:2902
 do_new_mount fs/namespace.c:2572 [inline] fs/namespace.c:2902
 do_mount+0xe65/0x2a10 fs/namespace.c:2902 fs/namespace.c:2902
 SYSC_mount fs/namespace.c:3118 [inline]
 SYSC_mount fs/namespace.c:3118 [inline] fs/namespace.c:3095
 SyS_mount+0xa8/0x120 fs/namespace.c:3095 fs/namespace.c:3095
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f6e55bd9579
RSP: 002b:00007fff88938738 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff88938770 RCX: 00007f6e55bd9579
RDX: 0000000020000040 RSI: 0000000020000140 RDI: 0000000020000080
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000f4240
R13: 0000000000000000 R14: 00007fff8893875c R15: 00007fff88938760
INFO: task syz-executor678:8010 blocked for more than 140 seconds.
      Not tainted 4.14.258-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor678 D27200  8010   8006 0x80000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 context_switch kernel/sched/core.c:2811 [inline] kernel/sched/core.c:3387
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 kernel/sched/core.c:3431
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3489 kernel/sched/core.c:3489
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock_common kernel/locking/mutex.c:833 [inline] kernel/locking/mutex.c:893
 __mutex_lock+0x669/0x1310 kernel/locking/mutex.c:893 kernel/locking/mutex.c:893
 lo_ioctl+0x87/0x1cd0 drivers/block/loop.c:1414 drivers/block/loop.c:1414
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 __blkdev_driver_ioctl block/ioctl.c:297 [inline] block/ioctl.c:594
 blkdev_ioctl+0x540/0x1830 block/ioctl.c:594 block/ioctl.c:594
 ioctl_by_bdev+0xa0/0x110 fs/block_dev.c:2092 fs/block_dev.c:2092
 udf_get_last_session+0x7c/0xd0 fs/udf/lowlevel.c:37 fs/udf/lowlevel.c:37
 udf_fill_super+0x11e6/0x1660 fs/udf/super.c:2159 fs/udf/super.c:2159
 mount_bdev+0x2b3/0x360 fs/super.c:1134 fs/super.c:1134
 mount_fs+0x92/0x2a0 fs/super.c:1237 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2572 [inline]
 vfs_kern_mount fs/namespace.c:1036 [inline] fs/namespace.c:2902
 do_new_mount fs/namespace.c:2572 [inline] fs/namespace.c:2902
 do_mount+0xe65/0x2a10 fs/namespace.c:2902 fs/namespace.c:2902
 SYSC_mount fs/namespace.c:3118 [inline]
 SYSC_mount fs/namespace.c:3118 [inline] fs/namespace.c:3095
 SyS_mount+0xa8/0x120 fs/namespace.c:3095 fs/namespace.c:3095
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f6e55bd9579
RSP: 002b:00007fff88938738 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff88938770 RCX: 00007f6e55bd9579
RDX: 0000000020000040 RSI: 0000000020000140 RDI: 0000000020000080
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000f4240
R13: 0000000000000000 R14: 00007fff8893875c R15: 00007fff88938760
INFO: task syz-executor678:8019 blocked for more than 140 seconds.
      Not tainted 4.14.258-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor678 D28912  8019   8016 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 context_switch kernel/sched/core.c:2811 [inline] kernel/sched/core.c:3387
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 kernel/sched/core.c:3431
 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] kernel/locking/rwsem-xadd.c:309
 rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309 kernel/locking/rwsem-xadd.c:309
 call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94 arch/x86/lib/rwsem.S:94
 __down_read arch/x86/include/asm/rwsem.h:66 [inline]
 __down_read arch/x86/include/asm/rwsem.h:66 [inline] kernel/locking/rwsem.c:26
 down_read+0x44/0x80 kernel/locking/rwsem.c:26 kernel/locking/rwsem.c:26
 __get_super.part.0+0x271/0x390 fs/super.c:678 fs/super.c:678
 __get_super include/linux/spinlock.h:317 [inline]
 __get_super include/linux/spinlock.h:317 [inline] fs/super.c:707
 get_super+0x2b/0x50 fs/super.c:707 fs/super.c:707
 fsync_bdev+0x14/0xc0 fs/block_dev.c:495 fs/block_dev.c:495
 invalidate_partition+0x74/0xb0 block/genhd.c:1509 block/genhd.c:1509
 drop_partitions.isra.0+0x83/0x150 block/partition-generic.c:442 block/partition-generic.c:442
 rescan_partitions+0xa9/0x800 block/partition-generic.c:515 block/partition-generic.c:515
 __blkdev_reread_part+0x140/0x1d0 block/ioctl.c:173 block/ioctl.c:173
 blkdev_reread_part+0x23/0x40 block/ioctl.c:193 block/ioctl.c:193
 loop_reread_partitions drivers/block/loop.c:624 [inline]
 loop_reread_partitions drivers/block/loop.c:624 [inline] drivers/block/loop.c:1193
 loop_set_status+0xeeb/0x12b0 drivers/block/loop.c:1193 drivers/block/loop.c:1193
 loop_set_status64+0x92/0xe0 drivers/block/loop.c:1311 drivers/block/loop.c:1311
 lo_ioctl+0x587/0x1cd0 drivers/block/loop.c:1441 drivers/block/loop.c:1441
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 __blkdev_driver_ioctl block/ioctl.c:297 [inline] block/ioctl.c:594
 blkdev_ioctl+0x540/0x1830 block/ioctl.c:594 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1893 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 vfs_ioctl fs/ioctl.c:46 [inline] fs/ioctl.c:684
 file_ioctl fs/ioctl.c:500 [inline] fs/ioctl.c:684
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SYSC_ioctl fs/ioctl.c:701 [inline] fs/ioctl.c:692
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f6e55bd9427
RSP: 002b:00007fff889384d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fff88938500 RCX: 00007f6e55bd9427
RDX: 00007fff88938610 RSI: 0000000000004c04 RDI: 0000000000000004
RBP: 0000000000000004 R08: 00007fff88938370 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000555556554384 R14: 00007fff88938610 R15: 00007fff88938760
INFO: task syz-executor678:8020 blocked for more than 140 seconds.
      Not tainted 4.14.258-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor678 D27544  8020   8018 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 context_switch kernel/sched/core.c:2811 [inline] kernel/sched/core.c:3387
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 kernel/sched/core.c:3431
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3489 kernel/sched/core.c:3489
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock_common kernel/locking/mutex.c:833 [inline] kernel/locking/mutex.c:893
 __mutex_lock+0x669/0x1310 kernel/locking/mutex.c:893 kernel/locking/mutex.c:893
 __blkdev_get+0x191/0x1090 fs/block_dev.c:1455 fs/block_dev.c:1455
 blkdev_get+0x441/0x890 fs/block_dev.c:1611 fs/block_dev.c:1611
 blkdev_get_by_path+0x38/0xa0 fs/block_dev.c:1692 fs/block_dev.c:1692
 mount_bdev+0x4c/0x360 fs/super.c:1092 fs/super.c:1092
 mount_fs+0x92/0x2a0 fs/super.c:1237 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2572 [inline]
 vfs_kern_mount fs/namespace.c:1036 [inline] fs/namespace.c:2902
 do_new_mount fs/namespace.c:2572 [inline] fs/namespace.c:2902
 do_mount+0xe65/0x2a10 fs/namespace.c:2902 fs/namespace.c:2902
 SYSC_mount fs/namespace.c:3118 [inline]
 SYSC_mount fs/namespace.c:3118 [inline] fs/namespace.c:3095
 SyS_mount+0xa8/0x120 fs/namespace.c:3095 fs/namespace.c:3095
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f6e55bd9579
RSP: 002b:00007fff88938738 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff88938770 RCX: 00007f6e55bd9579
RDX: 0000000020000040 RSI: 0000000020000140 RDI: 0000000020000080
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000f4240
R13: 0000000000000000 R14: 00007fff8893875c R15: 00007fff88938760
INFO: task syz-executor678:8021 blocked for more than 140 seconds.
      Not tainted 4.14.258-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor678 D27544  8021   8015 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 context_switch kernel/sched/core.c:2811 [inline] kernel/sched/core.c:3387
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 kernel/sched/core.c:3431
 bd_prepare_to_claim fs/block_dev.c:1078 [inline]
 bd_start_claiming fs/block_dev.c:1149 [inline]
 bd_prepare_to_claim fs/block_dev.c:1078 [inline] fs/block_dev.c:1604
 bd_start_claiming fs/block_dev.c:1149 [inline] fs/block_dev.c:1604
 blkdev_get+0x3ee/0x890 fs/block_dev.c:1604 fs/block_dev.c:1604
 blkdev_get_by_path+0x38/0xa0 fs/block_dev.c:1692 fs/block_dev.c:1692
 mount_bdev+0x4c/0x360 fs/super.c:1092 fs/super.c:1092
 mount_fs+0x92/0x2a0 fs/super.c:1237 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2572 [inline]
 vfs_kern_mount fs/namespace.c:1036 [inline] fs/namespace.c:2902
 do_new_mount fs/namespace.c:2572 [inline] fs/namespace.c:2902
 do_mount+0xe65/0x2a10 fs/namespace.c:2902 fs/namespace.c:2902
 SYSC_mount fs/namespace.c:3118 [inline]
 SYSC_mount fs/namespace.c:3118 [inline] fs/namespace.c:3095
 SyS_mount+0xa8/0x120 fs/namespace.c:3095 fs/namespace.c:3095
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f6e55bd9579
RSP: 002b:00007fff88938738 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff88938770 RCX: 00007f6e55bd9579
RDX: 0000000020000040 RSI: 0000000020000140 RDI: 0000000020000080
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000f4240
R13: 0000000000000000 R14: 00007fff8893875c R15: 00007fff88938760
INFO: task syz-executor678:8022 blocked for more than 140 seconds.
      Not tainted 4.14.258-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor678 D27544  8022   8017 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 context_switch kernel/sched/core.c:2811 [inline] kernel/sched/core.c:3387
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 kernel/sched/core.c:3431
 bd_prepare_to_claim fs/block_dev.c:1078 [inline]
 bd_start_claiming fs/block_dev.c:1149 [inline]
 bd_prepare_to_claim fs/block_dev.c:1078 [inline] fs/block_dev.c:1604
 bd_start_claiming fs/block_dev.c:1149 [inline] fs/block_dev.c:1604
 blkdev_get+0x3ee/0x890 fs/block_dev.c:1604 fs/block_dev.c:1604
 blkdev_get_by_path+0x38/0xa0 fs/block_dev.c:1692 fs/block_dev.c:1692
 mount_bdev+0x4c/0x360 fs/super.c:1092 fs/super.c:1092
 mount_fs+0x92/0x2a0 fs/super.c:1237 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2572 [inline]
 vfs_kern_mount fs/namespace.c:1036 [inline] fs/namespace.c:2902
 do_new_mount fs/namespace.c:2572 [inline] fs/namespace.c:2902
 do_mount+0xe65/0x2a10 fs/namespace.c:2902 fs/namespace.c:2902
 SYSC_mount fs/namespace.c:3118 [inline]
 SYSC_mount fs/namespace.c:3118 [inline] fs/namespace.c:3095
 SyS_mount+0xa8/0x120 fs/namespace.c:3095 fs/namespace.c:3095
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f6e55bd9579
RSP: 002b:00007fff88938738 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff88938770 RCX: 00007f6e55bd9579
RDX: 0000000020000040 RSI: 0000000020000140 RDI: 0000000020000080
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000f4240
R13: 0000000000000000 R14: 00007fff8893875c R15: 00007fff88938760
INFO: task systemd-udevd:8044 blocked for more than 140 seconds.
      Not tainted 4.14.258-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
systemd-udevd   D28912  8044   4627 0x00000104
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 context_switch kernel/sched/core.c:2811 [inline] kernel/sched/core.c:3387
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 kernel/sched/core.c:3431
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3489 kernel/sched/core.c:3489
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock_common kernel/locking/mutex.c:833 [inline] kernel/locking/mutex.c:893
 __mutex_lock+0x669/0x1310 kernel/locking/mutex.c:893 kernel/locking/mutex.c:893
 __blkdev_get+0x191/0x1090 fs/block_dev.c:1455 fs/block_dev.c:1455
 blkdev_get+0x88/0x890 fs/block_dev.c:1611 fs/block_dev.c:1611
 blkdev_open+0x1cc/0x250 fs/block_dev.c:1772 fs/block_dev.c:1772
 do_dentry_open+0x44b/0xec0 fs/open.c:777 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 do_last fs/namei.c:3428 [inline] fs/namei.c:3569
 path_openat+0x628/0x2970 fs/namei.c:3569 fs/namei.c:3569
 do_filp_open+0x179/0x3c0 fs/namei.c:3603 fs/namei.c:3603
 do_sys_open+0x296/0x410 fs/open.c:1081 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f36c4bdf840
RSP: 002b:00007ffd87b65888 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 000055a490895140 RCX: 00007f36c4bdf840
RDX: 000055a490061fe3 RSI: 00000000000a0800 RDI: 000055a49088e8f0
RBP: 00007ffd87b65a00 R08: 000055a490061670 R09: 0000000000000010
R10: 000055a490061d0c R11: 0000000000000246 R12: 00007ffd87b65950
R13: 000055a49088e7d0 R14: 0000000000000003 R15: 000000000000000e

Showing all locks held in the system:
1 lock held by khungtaskd/1534:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8701ebe7>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 kernel/locking/lockdep.c:4548
2 locks held by syz-executor678/8010:
 #0:  (&type->s_umount_key#46/1){+.+.}, at: [<ffffffff81875bd6>] alloc_super fs/super.c:251 [inline]
 #0:  (&type->s_umount_key#46/1){+.+.}, at: [<ffffffff81875bd6>] alloc_super fs/super.c:251 [inline] fs/super.c:516
 #0:  (&type->s_umount_key#46/1){+.+.}, at: [<ffffffff81875bd6>] sget_userns+0x556/0xc10 fs/super.c:516 fs/super.c:516
 #1:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff838dc7c7>] lo_ioctl+0x87/0x1cd0 drivers/block/loop.c:1414 drivers/block/loop.c:1414
3 locks held by syz-executor678/8019:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff838dc7c7>] lo_ioctl+0x87/0x1cd0 drivers/block/loop.c:1414 drivers/block/loop.c:1414
 #1:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff830b9c4b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192 block/ioctl.c:192
 #2:  (&type->s_umount_key#47){.+.+}, at: [<ffffffff81877471>] __get_super.part.0+0x271/0x390 fs/super.c:678 fs/super.c:678
1 lock held by syz-executor678/8020:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81940301>] __blkdev_get+0x191/0x1090 fs/block_dev.c:1455 fs/block_dev.c:1455
1 lock held by systemd-udevd/8044:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81940301>] __blkdev_get+0x191/0x1090 fs/block_dev.c:1455 fs/block_dev.c:1455

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1534 Comm: khungtaskd Not tainted 4.14.258-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 lib/dump_stack.c:17 [inline] lib/dump_stack.c:58
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] kernel/hung_task.c:274
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] kernel/hung_task.c:274
 watchdog+0x5b9/0xb40 kernel/hung_task.c:274 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8 Comm: rcu_preempt Not tainted 4.14.258-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880b5420200 task.stack: ffff8880b5428000
RIP: 0010:mark_held_locks+0xb6/0xf0 kernel/locking/lockdep.c:2858 kernel/locking/lockdep.c:2858
RSP: 0018:ffff8880b542fc20 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8880b5420200 RCX: 0000000000000000
RDX: 1ffff11016a84150 RSI: 0000000000000000 RDI: ffff8880b5420a80
RBP: ffffffff81485580 R08: ffffffff8b9c0bf0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000297
R13: ffff8880b5420200 R14: ffff8880b542fd18 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ac4857020 CR3: 00000000a102a000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:2875 [inline]
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:2875 [inline] kernel/locking/lockdep.c:2930
 trace_hardirqs_on_caller+0x288/0x580 kernel/locking/lockdep.c:2930 kernel/locking/lockdep.c:2930
 del_timer_sync+0x1a0/0x240 kernel/time/timer.c:1238 kernel/time/timer.c:1238
 schedule_timeout+0x4b7/0xe90 kernel/time/timer.c:1748 kernel/time/timer.c:1748
 rcu_gp_kthread+0xc0a/0x1e60 kernel/rcu/tree.c:2255 kernel/rcu/tree.c:2255
 kthread+0x30d/0x420 kernel/kthread.c:232 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 arch/x86/entry/entry_64.S:404
Code: c0 75 4c 0f b6 46 22 44 89 e2 a8 03 0f 45 d5 a8 04 74 0c 4c 89 ef e8 0a ef ff ff 85 c0 74 11 83 c3 01 41 39 9d 80 08 00 00 7f af <b8> 01 00 00 00 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f c3 89 
----------------
Code disassembly (best guess):
   0:	c0 75 4c 0f          	shlb   $0xf,0x4c(%rbp)
   4:	b6 46                	mov    $0x46,%dh
   6:	22 44 89 e2          	and    -0x1e(%rcx,%rcx,4),%al
   a:	a8 03                	test   $0x3,%al
   c:	0f 45 d5             	cmovne %ebp,%edx
   f:	a8 04                	test   $0x4,%al
  11:	74 0c                	je     0x1f
  13:	4c 89 ef             	mov    %r13,%rdi
  16:	e8 0a ef ff ff       	callq  0xffffef25
  1b:	85 c0                	test   %eax,%eax
  1d:	74 11                	je     0x30
  1f:	83 c3 01             	add    $0x1,%ebx
  22:	41 39 9d 80 08 00 00 	cmp    %ebx,0x880(%r13)
  29:	7f af                	jg     0xffffffda
* 2b:	b8 01 00 00 00       	mov    $0x1,%eax <-- trapping instruction
  30:	48 83 c4 08          	add    $0x8,%rsp
  34:	5b                   	pop    %rbx
  35:	5d                   	pop    %rbp
  36:	41 5c                	pop    %r12
  38:	41 5d                	pop    %r13
  3a:	41 5e                	pop    %r14
  3c:	41 5f                	pop    %r15
  3e:	c3                   	retq
  3f:	89                   	.byte 0x89
----------------
Code disassembly (best guess):
   0:	c0 75 4c 0f          	shlb   $0xf,0x4c(%rbp)
   4:	b6 46                	mov    $0x46,%dh
   6:	22 44 89 e2          	and    -0x1e(%rcx,%rcx,4),%al
   a:	a8 03                	test   $0x3,%al
   c:	0f 45 d5             	cmovne %ebp,%edx
   f:	a8 04                	test   $0x4,%al
  11:	74 0c                	je     0x1f
  13:	4c 89 ef             	mov    %r13,%rdi
  16:	e8 0a ef ff ff       	callq  0xffffef25
  1b:	85 c0                	test   %eax,%eax
  1d:	74 11                	je     0x30
  1f:	83 c3 01             	add    $0x1,%ebx
  22:	41 39 9d 80 08 00 00 	cmp    %ebx,0x880(%r13)
  29:	7f af                	jg     0xffffffda
* 2b:	b8 01 00 00 00       	mov    $0x1,%eax <-- trapping instruction
  30:	48 83 c4 08          	add    $0x8,%rsp
  34:	5b                   	pop    %rbx
  35:	5d                   	pop    %rbp
  36:	41 5c                	pop    %r12
  38:	41 5d                	pop    %r13
  3a:	41 5e                	pop    %r14
  3c:	41 5f                	pop    %r15
  3e:	c3                   	retq
  3f:	89                   	.byte 0x89

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/12/18 01:05 linux-4.14.y 9dfbac0e6b86 44068e19 .config console log report syz C ci2-linux-4-14 INFO: task hung in blkdev_get
* Struck through repros no longer work on HEAD.