INFO: task hung in vt_resize

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: e1f7d50a Linux 4.14.160
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=179dbac6e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=46599517442ad9fb
dashboard link: https://syzkaller.appspot.com/bug?extid=d1dbf945b18cf3eec89b
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d1dbf9...@syzkaller.appspotmail.com

kobject: 'loop3' (ffff8880a40ef760): fill_kobj_path: path
= '/devices/virtual/block/loop3'
protocol 88fb is buggy, dev hsr_slave_0
kobject: 'loop1' (ffff8880a4050de0): kobject_uevent_env
kobject: 'loop1' (ffff8880a4050de0): fill_kobj_path: path
= '/devices/virtual/block/loop1'
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0
sclass=netlink_route_socket pig=8324 comm=syz-executor.5
INFO: task syz-executor.0:8314 blocked for more than 140 seconds.
Not tainted 4.14.160-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D29328 8314 7158 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1723
__down_common kernel/locking/semaphore.c:221 [inline]
__down+0x160/0x290 kernel/locking/semaphore.c:238
down+0x64/0x90 kernel/locking/semaphore.c:62
console_lock+0x28/0x80 kernel/printk/printk.c:2216
vt_resize+0x48/0xf0 drivers/tty/vt/vt.c:994
tiocswinsz drivers/tty/tty_io.c:2267 [inline]
tty_ioctl+0x73b/0x1320 drivers/tty/tty_io.c:2576
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a919
RSP: 002b:00007f313c8e5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000020000380 RSI: 0000000000005414 RDI: 0000000000000006
RBP: 000000000075c118 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f313c8e66d4
R13: 00000000004c5e37 R14: 00000000004dc2d8 R15: 00000000ffffffff
INFO: task syz-executor.5:8310 blocked for more than 140 seconds.
Not tainted 4.14.160-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D26480 8310 7156 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1723
__down_common kernel/locking/semaphore.c:221 [inline]
__down+0x160/0x290 kernel/locking/semaphore.c:238
down+0x64/0x90 kernel/locking/semaphore.c:62
console_lock+0x28/0x80 kernel/printk/printk.c:2216
vcs_open+0x41/0x80 drivers/tty/vt/vc_screen.c:599
chrdev_open+0x207/0x590 fs/char_dev.c:423
do_dentry_open+0x73b/0xeb0 fs/open.c:777
vfs_open+0x105/0x220 fs/open.c:891
do_last fs/namei.c:3425 [inline]
path_openat+0x8bd/0x3f70 fs/namei.c:3566
do_filp_open+0x18e/0x250 fs/namei.c:3600
do_sys_open+0x2c5/0x430 fs/open.c:1084
SYSC_openat fs/open.c:1111 [inline]
SyS_openat+0x30/0x40 fs/open.c:1105
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a919
RSP: 002b:00007fa6b9005c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a919
RDX: 0000000000000001 RSI: 00000000200000c0 RDI: ffffffffffffff9c
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa6b90066d4
R13: 00000000004c86f4 R14: 00000000004dfc50 R15: 00000000ffffffff
INFO: task syz-executor.5:8316 blocked for more than 140 seconds.
Not tainted 4.14.160-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D28640 8316 7156 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1723
__down_common kernel/locking/semaphore.c:221 [inline]
__down+0x160/0x290 kernel/locking/semaphore.c:238
down+0x64/0x90 kernel/locking/semaphore.c:62
console_lock+0x28/0x80 kernel/printk/printk.c:2216
vcs_open+0x41/0x80 drivers/tty/vt/vc_screen.c:599
chrdev_open+0x207/0x590 fs/char_dev.c:423
do_dentry_open+0x73b/0xeb0 fs/open.c:777
vfs_open+0x105/0x220 fs/open.c:891
do_last fs/namei.c:3425 [inline]
path_openat+0x8bd/0x3f70 fs/namei.c:3566
do_filp_open+0x18e/0x250 fs/namei.c:3600
do_sys_open+0x2c5/0x430 fs/open.c:1084
SYSC_openat fs/open.c:1111 [inline]
SyS_openat+0x30/0x40 fs/open.c:1105
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a919
RSP: 002b:00007fa6b8fc3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a919
RDX: 0000000000000001 RSI: 00000000200000c0 RDI: ffffffffffffff9c
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa6b8fc46d4
R13: 00000000004c86f4 R14: 00000000004dfc50 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1044:
#0: (tasklist_lock){.+.+}, at: [<ffffffff8148c8d8>]
debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544
1 lock held by rsyslogd/6988:
#0: (&f->f_pos_lock){+.+.}, at: [<ffffffff81966a5b>]
__fdget_pos+0xab/0xd0 fs/file.c:769
2 locks held by getty/7110:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f823>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491c76>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7111:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f823>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491c76>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7112:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f823>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491c76>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7113:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f823>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491c76>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7114:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f823>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491c76>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7115:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f823>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491c76>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7116:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f823>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491c76>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 1
CPU: 1 PID: 1044 Comm: khungtaskd Not tainted 4.14.160-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+0x142/0x197 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x141/0x189 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+0x5e7/0xb90 kernel/hung_task.c:274
kthread+0x319/0x430 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
CPU: 0 PID: 8258 Comm: syz-executor.0 Not tainted 4.14.160-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff888048342600 task.stack: ffff88803a888000
RIP: 0010:bitfill_aligned+0x6/0x190
drivers/video/fbdev/core/cfbfillrect.c:37
RSP: 0018:ffff88803a88f6f0 EFLAGS: 00000246
RAX: ffffffff8328b160 RBX: ffff88821931ae40 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8880000a0000 RDI: ffff88821931ae40
RBP: ffff88803a88f6f8 R08: 0000000000000100 R09: 0000000000000040
R10: ffffed10432b7beb R11: ffff8882195bdf5f R12: ffff8880000a0000
R13: 0000000000000000 R14: 0000000000000100 R15: 000000003b203eb7
FS: 00007f313c928700(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000007176b4 CR3: 00000000776f8000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
cfb_fillrect+0x3d0/0x720 drivers/video/fbdev/core/cfbfillrect.c:327
vga16fb_fillrect+0x618/0x1880 drivers/video/fbdev/vga16fb.c:951
bit_clear_margins+0x2d5/0x4f0 drivers/video/fbdev/core/bitblit.c:232
fbcon_clear_margins+0x292/0x320 drivers/video/fbdev/core/fbcon.c:1317
fbcon_switch+0xd38/0x1820 drivers/video/fbdev/core/fbcon.c:2299
redraw_screen+0x335/0x7c0 drivers/tty/vt/vt.c:688
vc_do_resize+0xc8a/0xec0 drivers/tty/vt/vt.c:954
vt_resize+0xaa/0xf0 drivers/tty/vt/vt.c:995
tiocswinsz drivers/tty/tty_io.c:2267 [inline]
tty_ioctl+0x73b/0x1320 drivers/tty/tty_io.c:2576
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a919
RSP: 002b:00007f313c927c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000020000380 RSI: 0000000000005414 RDI: 0000000000000006
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f313c9286d4
R13: 00000000004c5e37 R14: 00000000004dc2d8 R15: 00000000ffffffff
Code: e8 90 2b 5f fe 8b 45 c8 e9 2f fb ff ff e8 83 2b 5f fe e9 f4 fa ff ff
0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 <49> 89 cf 41
56 49 89 f6 41 55 41 54 41 89 d4 53 44 89 c3 48 83


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.