INFO: task hung in con

INFO: task hung in con_install
Status: upstream: reported on 2020/01/07 08:17
Reported-by: syzbot+370b0e19c5405cfd7173@syzkaller.appspotmail.com
First crash: 151d, last: 22d

similar bugs (2):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
linux-4.14	INFO: task hung in con_install			1	42d	42d	0/1	upstream: reported on 2020/04/18 15:03
linux-4.19	INFO: task hung in con_install			1	121d	121d	0/1	auto-closed as invalid on 2020/05/29 01:06

Sample crash report:

INFO: task syz-executor.0:26626 blocked for more than 143 seconds.
      Not tainted 5.7.0-rc4-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28576 26626   7039 0x00004004
Call Trace:
 context_switch kernel/sched/core.c:3367 [inline]
 __schedule+0x805/0xc90 kernel/sched/core.c:4083
 schedule+0x188/0x220 kernel/sched/core.c:4158
 schedule_timeout+0x43/0x250 kernel/time/timer.c:1874
 mark_held_locks kernel/locking/lockdep.c:3628 [inline]
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:3657 [inline]
 lockdep_hardirqs_on+0x4a4/0x8a0 kernel/locking/lockdep.c:3702
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
 _raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199
 __down_common+0x28a/0x520 kernel/locking/semaphore.c:220
 down+0x65/0xa0 kernel/locking/semaphore.c:61
 console_lock+0x24/0x70 kernel/printk/printk.c:2314
 con_install+0x50/0x650 drivers/tty/vt/vt.c:3247
 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline]
 tty_init_dev+0xc6/0x4c0 drivers/tty/tty_io.c:1341
 tty_open_by_driver drivers/tty/tty_io.c:1983 [inline]
 tty_open+0x7cd/0xca0 drivers/tty/tty_io.c:2031
 chrdev_open+0x498/0x580 fs/char_dev.c:414
 cd_forget+0x150/0x150 include/linux/spinlock.h:393
 do_dentry_open+0x82e/0x10b0 fs/open.c:797
 do_open fs/namei.c:3229 [inline]
 path_openat+0x2790/0x38b0 fs/namei.c:3346
 do_filp_open+0x191/0x3a0 fs/namei.c:3373
 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock+0x24/0x40 kernel/locking/spinlock.c:183
 do_sys_openat2+0x463/0x770 fs/open.c:1148
 do_sys_open fs/open.c:1164 [inline]
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1170 [inline]
 __se_sys_open fs/open.c:1168 [inline]
 __x64_sys_open+0x1af/0x1e0 fs/open.c:1168
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Showing all locks held in the system:
1 lock held by khungtaskd/1141:
 #0: ffffffff892e8550 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 net/mptcp/pm_netlink.c:860
1 lock held by in:imklog/6695:
 #0: ffff88809f379af0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x25d/0x2f0 fs/file.c:826
1 lock held by syz-executor.4/26622:
2 locks held by syz-executor.0/26626:
 #0: ffffffff89475378 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:1947 [inline]
 #0: ffffffff89475378 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x338/0xca0 drivers/tty/tty_io.c:2031
 #1: ffff8880927671c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x6a/0x4c0 drivers/tty/tty_io.c:1340

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

NMI backtrace for cpu 0
CPU: 0 PID: 1141 Comm: khungtaskd Not tainted 5.7.0-rc4-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+0x1e9/0x30e lib/dump_stack.c:118
 nmi_cpu_backtrace+0x9f/0x180 lib/nmi_backtrace.c:101
 arch_trigger_cpumask_backtrace+0x10/0x10 arch/x86/kernel/apic/hw_nmi.c:38
 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xd2a/0xd40 kernel/hung_task.c:289
 kthread+0x353/0x380 kernel/kthread.c:268
 hungtask_pm_notify+0x50/0x50 kernel/hung_task.c:265
 kthread_blkcg+0xd0/0xd0 kernel/kthread.c:1247
 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: 26622 Comm: syz-executor.4 Not tainted 5.7.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:vga16fb_fillrect+0xfd4/0x13e0 drivers/video/fbdev/vga16fb.c:922
Code: b2 c9 a1 fd 49 ff c5 45 85 e4 74 38 4d 01 f5 e8 a2 c9 a1 fd 41 ff cc 83 7c 24 18 00 74 1c 44 89 fd 0f 1f 44 00 00 41 88 5d 00 <85> ed 74 d1 49 ff c5 e8 80 c9 a1 fd ff cd eb ec e8 77 c9 a1 fd 45
RSP: 0018:ffffc90006e6f848 EFLAGS: 00000206
RAX: ffffffff83d1a830 RBX: 0000000000000000 RCX: 0000000000040000
RDX: ffffc90012090000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: 000000000000002d R08: ffffffff83d1a7eb R09: ffffffff83d19f5f
R10: ffff8880a4040080 R11: 0000000000000002 R12: 00000000dc218571
R13: ffff8880000a0022 R14: ffffffffffffffb0 R15: 000000000000004f
FS:  00007f77ca9f8700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0001f3c80 CR3: 00000000a43f0000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bit_clear_margins+0x37b/0x620 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins drivers/video/fbdev/core/fbcon.c:1381 [inline]
 fbcon_do_set_font+0xce2/0x1220 drivers/video/fbdev/core/fbcon.c:2613
 fbcon_set_font+0x782/0x970 drivers/video/fbdev/core/fbcon.c:2705
 fbcon_blank+0x930/0x930 drivers/video/fbdev/core/fbcon.c:2390
 con_font_set drivers/tty/vt/vt.c:4566 [inline]
 con_font_op+0xebc/0x1630 drivers/tty/vt/vt.c:4631
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0x125/0x190 mm/kasan/common.c:456
 vt_ioctl+0x179d/0x3eb0 drivers/tty/vt/vt_ioctl.c:265
 rcu_lock_release+0x5/0x20 include/linux/rcupdate.h:212
 tomoyo_path_number_perm+0x58f/0x690 security/tomoyo/file.c:739
 tty_jobctrl_ioctl+0x1e8/0xc20 drivers/tty/tty_jobctrl.c:539
 tty_ioctl+0xee4/0x15c0 drivers/tty/tty_io.c:2656
 tty_do_resize+0x180/0x180 drivers/tty/tty_io.c:2248
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl fs/ioctl.c:771 [inline]
 __do_sys_ioctl fs/ioctl.c:780 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:778
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f77ca9f7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e6920 RCX: 000000000045c829
RDX: 0000000020000000 RSI: 0000000000004b61 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000375 R14: 00000000004c5e6f R15: 00007f77ca9f86d4

Crashes (4):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Maintainers
ci-upstream-kasan-gce-smack-root	2020/05/07 23:50	upstream	6e7f2eac	6c70a1c2	.config	log	report	daniel.vetter@ffwll.ch, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net, sam@ravnborg.org
ci-upstream-kasan-gce	2020/03/05 17:38	upstream	63623fd4	c88c7b75	.config	log	report	b.zolnierkie@samsung.com, daniel.vetter@ffwll.ch, ghalat@redhat.com, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, lukas@wunner.de, nico@fluxnic.net, okash.khawaja@gmail.com, sam@ravnborg.org
ci-upstream-kasan-gce-selinux-root	2020/01/20 14:19	upstream	def9d278	d2557fb5	.config	log	report	daniel.vetter@ffwll.ch, ghalat@redhat.com, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, maarten.lankhorst@linux.intel.com, nico@fluxnic.net, okash.khawaja@gmail.com, oleksandr@redhat.com, sam@ravnborg.org
ci-upstream-kasan-gce-root	2019/12/30 22:36	upstream	fd698849	af6b8ef8	.config	log	report	daniel.vetter@ffwll.ch, ghalat@redhat.com, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net, sam@ravnborg.org, textshell@uchuujin.de