syzbot


INFO: task hung in loop_control_ioctl (2)

Status: upstream: reported C repro on 2020/02/29 17:00
Reported-by: syzbot+aca8490dd31a8e51f127@syzkaller.appspotmail.com
First crash: 1574d, last: 653d
Fix bisection the fix commit could be any of (bisect log):
  78d697fc93f9 Linux 4.14.172
  4139fb08c05f Linux 4.14.187
  
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in loop_control_ioctl block 4 2080d 2274d 11/27 fixed on 2019/01/15 20:25
android-414 INFO: task hung in loop_control_ioctl C 23 1700d 1897d 0/1 public: reported C repro on 2019/04/13 00:01
android-49 INFO: task hung in loop_control_ioctl C 59 1669d 1898d 0/3 public: reported C repro on 2019/04/12 00:00
android-44 INFO: task hung in loop_control_ioctl 6 2241d 2365d 0/2 auto-closed as invalid on 2019/02/22 15:22
linux-4.14 INFO: task hung in loop_control_ioctl 1 1731d 1731d 0/1 auto-closed as invalid on 2020/01/24 04:19
Fix bisection attempts (3)
Created Duration User Patch Repo Result
2020/06/25 20:55 37m (4) bisect fix linux-4.14.y job log (2)
2020/05/26 20:16 39m bisect fix linux-4.14.y job log (0) log
2020/03/30 16:59 39m bisect fix linux-4.14.y job log (0) log

Sample crash report:
audit: type=1400 audit(1582995064.265:36): avc:  denied  { map } for  pid=7488 comm="syz-executor848" path="/root/syz-executor848947954" dev="sda1" ino=1426 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
INFO: task syz-executor848:7517 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor848 D26960  7517   7494 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 loop_control_ioctl+0x15b/0x2d0 drivers/block/loop.c:2007
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441b09
RSP: 002b:00007ffcd646a208 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441b09
RDX: 9999999999999999 RSI: 0000000000004c81 RDI: 0000000000000004
RBP: 00000000000bce1f R08: 00000000004028b0 R09: 00000000004028b0
R10: 00000000004028b0 R11: 0000000000000246 R12: 0000000000402820
R13: 00000000004028b0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor848:7519 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor848 D27408  7519   7489 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
 loop_reread_partitions+0x72/0x80 drivers/block/loop.c:624
 loop_clr_fd+0x839/0xad0 drivers/block/loop.c:1078
 lo_ioctl+0x8a5/0x1c40 drivers/block/loop.c:1424
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1881
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441a17
RSP: 002b:00007ffcd6469fa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000441a17
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000000c
R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000402820
R13: 00000000004028b0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor848:7520 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor848 D28688  7520   7490 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
 loop_reread_partitions+0x72/0x80 drivers/block/loop.c:624
 loop_set_status+0xbfc/0x11f0 drivers/block/loop.c:1193
 loop_set_status64+0x92/0xe0 drivers/block/loop.c:1311
 lo_ioctl+0x590/0x1c40 drivers/block/loop.c:1441
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1881
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441a17
RSP: 002b:00007ffcd6469fa8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000441a17
RDX: 00007ffcd646a070 RSI: 0000000000004c04 RDI: 0000000000000004
RBP: 00000000000bce21 R08: 0000000000000000 R09: 000000000000000a
R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000402820
R13: 00000000004028b0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor848:7521 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor848 D27408  7521   7492 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
 loop_reread_partitions+0x72/0x80 drivers/block/loop.c:624
 loop_clr_fd+0x839/0xad0 drivers/block/loop.c:1078
 lo_ioctl+0x8a5/0x1c40 drivers/block/loop.c:1424
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1881
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441a17
RSP: 002b:00007ffcd6469fa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000441a17
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000000c
R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000402820
R13: 00000000004028b0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor848:7522 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor848 D28688  7522   7493 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
 loop_reread_partitions+0x72/0x80 drivers/block/loop.c:624
 loop_set_status+0xbfc/0x11f0 drivers/block/loop.c:1193
 loop_set_status64+0x92/0xe0 drivers/block/loop.c:1311
 lo_ioctl+0x590/0x1c40 drivers/block/loop.c:1441
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1881
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441a17
RSP: 002b:00007ffcd6469fa8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000441a17
RDX: 00007ffcd646a070 RSI: 0000000000004c04 RDI: 0000000000000004
RBP: 00000000000bce32 R08: 0000000000000000 R09: 000000000000000a
R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000402820
R13: 00000000004028b0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor848:7523 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor848 D26832  7523   7491 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
 loop_reread_partitions+0x72/0x80 drivers/block/loop.c:624
 loop_set_status+0xbfc/0x11f0 drivers/block/loop.c:1193
 loop_set_status64+0x92/0xe0 drivers/block/loop.c:1311
 lo_ioctl+0x590/0x1c40 drivers/block/loop.c:1441
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1881
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441a17
RSP: 002b:00007ffcd6469fa8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000441a17
RDX: 00007ffcd646a070 RSI: 0000000000004c04 RDI: 0000000000000004
RBP: 00000000000bce3b R08: 0000000000000000 R09: 000000000000000a
R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000402820
R13: 00000000004028b0 R14: 0000000000000000 R15: 0000000000000000
INFO: task blkid:7526 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid           D29200  7526   7473 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 lo_open+0x19/0xb0 drivers/block/loop.c:1634
 __blkdev_get+0xa70/0x10d0 fs/block_dev.c:1537
 blkdev_get+0x84/0x8a0 fs/block_dev.c:1612
 blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
 do_dentry_open+0x732/0xe90 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:891
 do_last fs/namei.c:3428 [inline]
 path_openat+0x8ca/0x3c50 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x29d/0x3f0 fs/open.c:1084
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7f12ea021120
RSP: 002b:00007ffc3106ba78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f12ea021120
RDX: 00007ffc3106cf41 RSI: 0000000000000000 RDI: 00007ffc3106cf41
RBP: 0000000000000000 R08: 0000000000000078 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000017e1030
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005
INFO: task blkid:7527 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid           D29200  7527   7513 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 lo_open+0x19/0xb0 drivers/block/loop.c:1634
 __blkdev_get+0xa70/0x10d0 fs/block_dev.c:1537
 blkdev_get+0x84/0x8a0 fs/block_dev.c:1612
 blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
 do_dentry_open+0x732/0xe90 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:891
 do_last fs/namei.c:3428 [inline]
 path_openat+0x8ca/0x3c50 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x29d/0x3f0 fs/open.c:1084
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7f3b61993120
RSP: 002b:00007fff489797b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3b61993120
RDX: 00007fff4897bf34 RSI: 0000000000000000 RDI: 00007fff4897bf34
RBP: 0000000000000000 R08: 0000000000000078 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000007e7030
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005
INFO: task blkid:7528 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid           D29200  7528   7501 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 lo_open+0x19/0xb0 drivers/block/loop.c:1634
 __blkdev_get+0xa70/0x10d0 fs/block_dev.c:1537
 blkdev_get+0x84/0x8a0 fs/block_dev.c:1612
 blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
 do_dentry_open+0x732/0xe90 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:891
 do_last fs/namei.c:3428 [inline]
 path_openat+0x8ca/0x3c50 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x29d/0x3f0 fs/open.c:1084
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7f49a9a84120
RSP: 002b:00007ffcdcc67598 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f49a9a84120
RDX: 00007ffcdcc68f41 RSI: 0000000000000000 RDI: 00007ffcdcc68f41
RBP: 0000000000000000 R08: 0000000000000078 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000015e8030
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005
INFO: task blkid:7532 blocked for more than 140 seconds.
      Not tainted 4.14.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid           D28272  7532   7503 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 lo_open+0x19/0xb0 drivers/block/loop.c:1634
 __blkdev_get+0xa70/0x10d0 fs/block_dev.c:1537
 blkdev_get+0x84/0x8a0 fs/block_dev.c:1612
 blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
 do_dentry_open+0x732/0xe90 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:891
 do_last fs/namei.c:3428 [inline]
 path_openat+0x8ca/0x3c50 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x29d/0x3f0 fs/open.c:1084
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7f6511807120
RSP: 002b:00007ffd7cb03a58 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6511807120
RDX: 00007ffd7cb05f41 RSI: 0000000000000000 RDI: 00007ffd7cb05f41
RBP: 0000000000000000 R08: 0000000000000078 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000758030
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005

Showing all locks held in the system:
1 lock held by khungtaskd/1054:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff81465b23>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544
2 locks held by getty/7464:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833aa792>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8339e3d4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7465:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833aa792>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8339e3d4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7466:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833aa792>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8339e3d4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7467:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833aa792>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8339e3d4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7468:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833aa792>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8339e3d4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7469:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833aa792>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8339e3d4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7470:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833aa792>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8339e3d4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by syz-executor848/7517:
 #0:  (loop_index_mutex){+.+.}, at: [<ffffffff839d1341>] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993
 #1:  (&lo->lo_ctl_mutex#2){+.+.}, at: [<ffffffff839d143b>] loop_control_ioctl+0x15b/0x2d0 drivers/block/loop.c:2007
2 locks held by syz-executor848/7519:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff839d1797>] lo_ioctl+0x87/0x1c40 drivers/block/loop.c:1414
 #1:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff82f08c4b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
2 locks held by syz-executor848/7520:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff839d1797>] lo_ioctl+0x87/0x1c40 drivers/block/loop.c:1414
 #1:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff82f08c4b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
2 locks held by syz-executor848/7521:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff839d1797>] lo_ioctl+0x87/0x1c40 drivers/block/loop.c:1414
 #1:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff82f08c4b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
2 locks held by syz-executor848/7522:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff839d1797>] lo_ioctl+0x87/0x1c40 drivers/block/loop.c:1414
 #1:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff82f08c4b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
2 locks held by syz-executor848/7523:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff839d1797>] lo_ioctl+0x87/0x1c40 drivers/block/loop.c:1414
 #1:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff82f08c4b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
2 locks held by blkid/7526:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff8197c9c1>] __blkdev_get+0x131/0x10d0 fs/block_dev.c:1457
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff839cb189>] lo_open+0x19/0xb0 drivers/block/loop.c:1634
2 locks held by blkid/7527:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff8197c9c1>] __blkdev_get+0x131/0x10d0 fs/block_dev.c:1457
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff839cb189>] lo_open+0x19/0xb0 drivers/block/loop.c:1634
2 locks held by blkid/7528:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff8197c9c1>] __blkdev_get+0x131/0x10d0 fs/block_dev.c:1457
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff839cb189>] lo_open+0x19/0xb0 drivers/block/loop.c:1634
2 locks held by blkid/7532:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff8197c9c1>] __blkdev_get+0x131/0x10d0 fs/block_dev.c:1457
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff839cb189>] lo_open+0x19/0xb0 drivers/block/loop.c:1634
2 locks held by blkid/7536:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff8197c9c1>] __blkdev_get+0x131/0x10d0 fs/block_dev.c:1457
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff839cb189>] lo_open+0x19/0xb0 drivers/block/loop.c:1634
2 locks held by blkid/7537:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff8197c9c1>] __blkdev_get+0x131/0x10d0 fs/block_dev.c:1457
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff839cb189>] lo_open+0x19/0xb0 drivers/block/loop.c:1634

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

NMI backtrace for cpu 1
CPU: 1 PID: 1054 Comm: khungtaskd Not tainted 4.14.172-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+0x13e/0x194 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x139/0x17e 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]
 watchdog+0x5e2/0xb80 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff86401cbe

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/02/29 16:59 linux-4.14.y 78d697fc93f9 c88c7b75 .config console log report syz C ci2-linux-4-14
2022/09/07 21:32 linux-4.14.y 65640c873dcf c5b7bc57 .config console log report info [disk image] [vmlinux] ci2-linux-4-14 INFO: task hung in loop_control_ioctl
2022/07/21 02:59 linux-4.14.y 424a46ea058e 88cb1383 .config console log report info ci2-linux-4-14 INFO: task hung in loop_control_ioctl
2021/05/16 21:53 linux-4.14.y 7d7d1c0ab3eb f54a5c09 .config console log report info ci2-linux-4-14 INFO: task hung in loop_control_ioctl
2021/04/29 22:54 linux-4.14.y 7d7d1c0ab3eb 77e2b668 .config console log report info ci2-linux-4-14 INFO: task hung in loop_control_ioctl
2021/01/22 08:01 linux-4.14.y 2762b48e9611 d4f4eca5 .config console log report info ci2-linux-4-14 INFO: task hung in loop_control_ioctl
2020/04/26 20:16 linux-4.14.y 050272a0423e 0ce7569e .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.