linux-kernel - INFO: task hung in ctrl_cdev

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Message-ID: <000000000000337c5e059bd16c9d@google.com>
Date:   Fri, 10 Jan 2020 15:24:09 -0800
From:   syzbot <syzbot+12eda31c0851e1cdabf4@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org,
        miquel.raynal@...tlin.com, richard@....at,
        syzkaller-bugs@...glegroups.com, vigneshr@...com
Subject: INFO: task hung in ctrl_cdev_ioctl

Hello,

syzbot found the following crash on:

HEAD commit:    b07f636f Merge tag 'tpmdd-next-20200108' of git://git.infr..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1622069ee00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=18698c0c240ba616
dashboard link: https://syzkaller.appspot.com/bug?extid=12eda31c0851e1cdabf4
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13bb85c6e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+12eda31c0851e1cdabf4@...kaller.appspotmail.com

INFO: task syz-executor.3:13404 blocked for more than 143 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D27816 13404   9705 0x00004004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007fdf84a75c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf84a766d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.0:13413 blocked for more than 143 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28536 13413   9712 0x00004004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007fbe949bbc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbe949bc6d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.1:13418 blocked for more than 143 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D27816 13418   9711 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007f3b1600dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3b1600e6d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.5:13424 blocked for more than 144 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D27816 13424   9713 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007fd996268c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd9962696d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.5:13425 blocked for more than 144 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D28536 13425   9713 0x00004004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871
  do_wait_for_common kernel/sched/completion.c:83 [inline]
  __wait_for_common kernel/sched/completion.c:104 [inline]
  wait_for_common kernel/sched/completion.c:115 [inline]
  wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136
  kthread_stop+0x187/0x800 kernel/kthread.c:559
  ubi_detach_mtd_dev+0x219/0x402 drivers/mtd/ubi/build.c:1080
  ctrl_cdev_ioctl+0x1d6/0x2d0 drivers/mtd/ubi/cdev.c:1068
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007fd996247c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040046f41 RDI: 0000000000000004
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd9962486d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.4:13428 blocked for more than 144 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D28536 13428   9703 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007f3b65a23c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3b65a246d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.4:13430 blocked for more than 144 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D28536 13430   9703 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x1cd/0x2d0 drivers/mtd/ubi/cdev.c:1067
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007f3b65a02c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040046f41 RDI: 0000000000000004
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3b65a036d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.4:13440 blocked for more than 145 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D29712 13440   9703 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007f3b659e1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3b659e26d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.2:13435 blocked for more than 145 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2  D28536 13435   9707 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007f0382d55c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040186f40 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0382d566d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff
INFO: task syz-executor.2:13436 blocked for more than 145 seconds.
       Not tainted 5.5.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2  D28536 13436   9707 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:3385 [inline]
  __schedule+0x934/0x1f90 kernel/sched/core.c:4081
  schedule+0xdc/0x2b0 kernel/sched/core.c:4155
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
  __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
  __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
  ctrl_cdev_ioctl+0x1cd/0x2d0 drivers/mtd/ubi/cdev.c:1067
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: cc e9 1b c6 ff ff cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 b8 e7  
00 00 00 0f 05 c3 cc cc cc cc 48 8b 44 24 08 c7 00 00 00 <00> 00 bf 00 00  
00 00 b8 3c 00 00 00 0f 05 cd 03 eb fe cc cc cc cc
RSP: 002b:00007f0382d34c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000000076006e RSI: 0000000040046f41 RDI: 0000000000000004
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0382d356d4
R13: 00000000004c288a R14: 00000000004d8b90 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1115:
  #0: ffffffff899a5340 (rcu_read_lock){....}, at:  
debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334
2 locks held by getty/9655:
  #0: ffff88808f490090 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
  #1: ffffc9000178b2e0 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9656:
  #0: ffff88809fa7f090 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
  #1: ffffc9000177b2e0 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9657:
  #0: ffff8880a0677090 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
  #1: ffffc900017cb2e0 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9658:
  #0: ffff8880a2e1f090 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
  #1: ffffc900017bb2e0 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9659:
  #0: ffff8880a1bdd090 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
  #1: ffffc900017db2e0 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9660:
  #0: ffff8880940c4090 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
  #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9661:
  #0: ffff8880a874e090 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
  #1: ffffc900017232e0 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.3/13404:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
1 lock held by syz-executor.0/13413:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
1 lock held by syz-executor.1/13418:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
1 lock held by syz-executor.5/13424:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
1 lock held by syz-executor.5/13425:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x1cd/0x2d0 drivers/mtd/ubi/cdev.c:1067
1 lock held by syz-executor.4/13428:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
1 lock held by syz-executor.4/13430:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x1cd/0x2d0 drivers/mtd/ubi/cdev.c:1067
1 lock held by syz-executor.4/13440:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
1 lock held by syz-executor.2/13435:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042
1 lock held by syz-executor.2/13436:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x1cd/0x2d0 drivers/mtd/ubi/cdev.c:1067
1 lock held by syz-executor.2/13442:
  #0: ffffffff8a0dc340 (ubi_devices_mutex){+.+.}, at:  
ctrl_cdev_ioctl+0x22b/0x2d0 drivers/mtd/ubi/cdev.c:1042

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

NMI backtrace for cpu 0
CPU: 0 PID: 1115 Comm: khungtaskd Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x197/0x210 lib/dump_stack.c:118
  nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
  nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline]
  check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
  watchdog+0xb11/0x10c0 kernel/hung_task.c:289
  kthread+0x361/0x430 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 451 Comm: kworker/u4:5 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
RIP: 0010:rcu_read_lock include/linux/rcupdate.h:618 [inline]
RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:407  
[inline]
RIP: 0010:batadv_nc_worker+0x128/0x760 net/batman-adv/network-coding.c:718
Code: d2 31 f6 b9 02 00 00 00 68 03 2f b9 87 48 c7 c7 40 53 9a 89 e8 09 da  
a1 f9 e8 d4 30 a8 f9 31 ff 41 89 c4 89 c6 e8 28 f9 bb f9 <45> 85 e4 58 74  
20 e8 9d f7 bb f9 44 0f b6 25 65 bf bd 02 31 ff 44
RSP: 0018:ffffc90002747cd8 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffff8880a6abe900 RCX: ffffffff87b92f48
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000005
RBP: ffffc90002747d30 R08: ffff8880a87e0340 R09: fffffbfff165eba5
R10: ffff8880a87e0c28 R11: ffff8880a87e0340 R12: 0000000000000001
R13: 000000000000008a R14: ffff88808e188450 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 000000009ec9c000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  process_one_work+0x9af/0x1740 kernel/workqueue.c:2264
  worker_thread+0x98/0xe40 kernel/workqueue.c:2410
  kthread+0x361/0x430 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352


---
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