syzbot


INFO: task hung in lo_release (2)

Status: auto-closed as invalid on 2020/03/16 04:39
Reported-by: syzbot+89caea70641cef1f152c@syzkaller.appspotmail.com
First crash: 1625d, last: 1613d
Similar bugs (7)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in lo_release block 1 2100d 2100d 11/26 fixed on 2019/01/15 20:25
android-49 INFO: task hung in lo_release 867 1735d 1830d 0/3 auto-closed as invalid on 2019/10/25 14:11
linux-4.14 INFO: task hung in lo_release (2) C 19 417d 1491d 0/1 upstream: reported C repro on 2020/03/19 00:28
upstream INFO: task hung in lo_release (2) block 38 877d 877d 0/26 closed as dup on 2021/11/23 00:29
android-414 INFO: task hung in lo_release syz 1670 1608d 1833d 0/1 public: reported syz repro on 2019/04/12 00:01
android-44 INFO: task hung in lo_release syz 59 1601d 1831d 0/2 public: reported syz repro on 2019/04/14 00:02
linux-4.14 INFO: task hung in lo_release syz done 128 1720d 1833d 1/1 fixed on 2019/12/17 00:29

Sample crash report:
INFO: task syz-executor.0:2131 blocked for more than 140 seconds.
      Not tainted 4.9.202+ #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D25544  2131      1 0x00000004
 0000000000000083 ffff8801cee82f80 0000000000000000 ffff8801db61ffc0
 ffffffff83031180 ffff8801db61ffd8 ffff8801a5dafb18 ffffffff8280a1de
 0000000000000046 0000000000000000 00ff8801cee82f80 ffff8801db6208b0
Call Trace:
 [<0000000034a28390>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<0000000050fc0b20>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<0000000047cfb80d>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<0000000047cfb80d>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<000000005ff16b64>] lo_release+0x20/0x1b0 drivers/block/loop.c:1664
 [<000000001ba1afea>] __blkdev_put+0x461/0x840 fs/block_dev.c:1606
 [<00000000b4190e93>] blkdev_put+0x88/0x560 fs/block_dev.c:1671
 [<00000000d8eadca5>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1678
 [<00000000bb8ef7cd>] __fput+0x274/0x720 fs/file_table.c:208
 [<00000000325e2cbd>] ____fput+0x16/0x20 fs/file_table.c:244
 [<00000000659bdba5>] task_work_run+0x108/0x180 kernel/task_work.c:116
 [<0000000078553dbf>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<0000000078553dbf>] exit_to_usermode_loop+0x13b/0x160 arch/x86/entry/common.c:163
 [<00000000fbf07d77>] prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 [<00000000fbf07d77>] syscall_return_slowpath arch/x86/entry/common.c:266 [inline]
 [<00000000fbf07d77>] do_syscall_64+0x3ab/0x5c0 arch/x86/entry/common.c:293
 [<000000009574e945>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<000000004f1ae7d4>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline]
 #0:  (rcu_read_lock){......}, at: [<000000004f1ae7d4>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263
 #1:  (tasklist_lock){.+.+..}, at: [<0000000084a91545>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339
1 lock held by rsyslogd/1902:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<000000007d6e58c3>] __fdget_pos+0xa8/0xd0 fs/file.c:782
2 locks held by getty/2030:
 #0:  (&tty->ldisc_sem){++++++}, at: [<000000003d166517>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<000000003176f4cf>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.0/2131:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<0000000078b0500c>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587
 #1:  (loop_index_mutex){+.+.+.}, at: [<000000005ff16b64>] lo_release+0x20/0x1b0 drivers/block/loop.c:1664
2 locks held by syz-executor.1/3805:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000d6dc1c63>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<0000000090f7b539>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189
2 locks held by syz-executor.4/3808:
 #0:  (loop_index_mutex){+.+.+.}, at: [<000000007ddbf89f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974
 #1:  (&lo->lo_ctl_mutex#2){+.+...}, at: [<00000000818fd02c>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1988
2 locks held by blkid/3810:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000004b8f96a7>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<000000001a52975d>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
1 lock held by blkid/3812:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000004b8f96a7>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.202+ #0
 ffff8801d98d7cc8 ffffffff81b55d2b 0000000000000001 0000000000000000
 0000000000000001 ffffffff8109a001 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b60fcc 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<0000000068f927da>] __dump_stack lib/dump_stack.c:15 [inline]
 [<0000000068f927da>] dump_stack+0xcb/0x130 lib/dump_stack.c:56
 [<00000000d3ea3dfb>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<00000000d9a147b1>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<00000000c8cb3140>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<000000009d59c717>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<000000009d59c717>] check_hung_task kernel/hung_task.c:126 [inline]
 [<000000009d59c717>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<000000009d59c717>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<00000000366892e5>] kthread+0x278/0x310 kernel/kthread.c:211
 [<000000008389186e>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff82819331

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/11/17 04:38 android-4.9 258971b8e1ac d5696d51 .config console log report ci-android-49-kasan-gce-root
2019/11/08 01:57 https://android.googlesource.com/kernel/common android-4.9 7fe05eede1c8 f39aff9e .config console log report ci-android-49-kasan-gce-root
2019/11/05 09:02 https://android.googlesource.com/kernel/common android-4.9 7fe05eede1c8 76630fc9 .config console log report ci-android-49-kasan-gce-root
* Struck through repros no longer work on HEAD.