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: 224d, last: 34d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
linux-4.14	INFO: task hung in con_install	1	114d	114d	0/1	upstream: reported on 2020/04/18 15:03
linux-4.19	INFO: task hung in con_install (2)	1	60d	60d	0/1	upstream: reported on 2020/06/11 22:35
linux-4.19	INFO: task hung in con_install	1	193d	193d	0/1	auto-closed as invalid on 2020/05/29 01:06

Sample crash report:

INFO: task syz-executor.1:10663 blocked for more than 143 seconds.
      Not tainted 5.8.0-rc3-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D27896 10663   6937 0x00004004
Call Trace:
 context_switch kernel/sched/core.c:3453 [inline]
 __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4178
 schedule+0xd0/0x2a0 kernel/sched/core.c:4253
 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1873
 __down_common kernel/locking/semaphore.c:220 [inline]
 __down+0x183/0x2a0 kernel/locking/semaphore.c:237
 down+0x57/0x80 kernel/locking/semaphore.c:61
 console_lock+0x25/0x80 kernel/printk/printk.c:2309
 con_install+0x8c/0x5c0 drivers/tty/vt/vt.c:3252
 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline]
 tty_init_dev.part.0+0x9e/0x610 drivers/tty/tty_io.c:1341
 tty_init_dev include/linux/err.h:36 [inline]
 tty_open_by_driver drivers/tty/tty_io.c:1983 [inline]
 tty_open+0xb2e/0xf60 drivers/tty/tty_io.c:2031
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x501/0x1290 fs/open.c:828
 do_open fs/namei.c:3243 [inline]
 path_openat+0x1bb9/0x2750 fs/namei.c:3360
 do_filp_open+0x17e/0x3c0 fs/namei.c:3387
 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179
 do_sys_open fs/open.c:1195 [inline]
 ksys_open include/linux/syscalls.h:1388 [inline]
 __do_sys_open fs/open.c:1201 [inline]
 __se_sys_open fs/open.c:1199 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1199
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416921
Code: Bad RIP value.
RSP: 002b:00007f55346a67a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 000000000050ade0 RCX: 0000000000416921
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007f55346a67d0
RBP: 000000000078bf00 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000064 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000c5d R14: 00000000004ceb70 R15: 00007f55346a76d4
INFO: task syz-executor.1:10665 blocked for more than 143 seconds.
      Not tainted 5.8.0-rc3-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D28760 10665   6937 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:3453 [inline]
 __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4178
 schedule+0xd0/0x2a0 kernel/sched/core.c:4253
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4312
 __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
 __mutex_lock+0x3e2/0x10d0 kernel/locking/mutex.c:1103
 tty_open_by_driver drivers/tty/tty_io.c:1947 [inline]
 tty_open+0x51d/0xf60 drivers/tty/tty_io.c:2031
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x501/0x1290 fs/open.c:828
 do_open fs/namei.c:3243 [inline]
 path_openat+0x1bb9/0x2750 fs/namei.c:3360
 do_filp_open+0x17e/0x3c0 fs/namei.c:3387
 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179
 do_sys_open fs/open.c:1195 [inline]
 ksys_open include/linux/syscalls.h:1388 [inline]
 __do_sys_open fs/open.c:1201 [inline]
 __se_sys_open fs/open.c:1199 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1199
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416921
Code: Bad RIP value.
RSP: 002b:00007f55346857a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 000000000050ade0 RCX: 0000000000416921
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007f55346857d0
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000064 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000c5d R14: 00000000004ceb70 R15: 00007f55346866d4

Showing all locks held in the system:
1 lock held by khungtaskd/1147:
 #0: ffffffff89bc1180 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779
1 lock held by in:imklog/6483:
 #0: ffff8880a2da9630 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826
2 locks held by agetty/6497:
 #0: ffff888096ad7098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267
 #1: ffffc90000f942e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.5/10653:
2 locks held by syz-executor.1/10663:
 #0: ffffffff8a1762c8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:1947 [inline]
 #0: ffffffff8a1762c8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x51d/0xf60 drivers/tty/tty_io.c:2031
 #1: ffff88804fae51c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0xbd/0x120 drivers/tty/tty_mutex.c:19
1 lock held by syz-executor.1/10665:
 #0: ffffffff8a1762c8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:1947 [inline]
 #0: ffffffff8a1762c8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x51d/0xf60 drivers/tty/tty_io.c:2031

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

NMI backtrace for cpu 0
CPU: 0 PID: 1147 Comm: khungtaskd Not tainted 5.8.0-rc3-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+0x18f/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline]
 watchdog+0xd7d/0x1000 kernel/hung_task.c:295
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 10653 Comm: syz-executor.5 Not tainted 5.8.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__sanitizer_cov_trace_pc+0x55/0x60 kernel/kcov.c:207
Code: 82 e0 13 00 00 83 f8 02 75 20 48 8b 8a e8 13 00 00 8b 92 e4 13 00 00 48 8b 01 48 83 c0 01 48 39 c2 76 07 48 89 34 c1 48 89 01 <c3> 66 2e 0f 1f 84 00 00 00 00 00 41 55 41 54 49 89 fc 55 48 bd eb
RSP: 0018:ffffc9000402f878 EFLAGS: 00000246
RAX: 0000000000040000 RBX: 0000000000000050 RCX: ffffc90014127000
RDX: 0000000000040000 RSI: ffffffff83c64690 RDI: 0000000000000004
RBP: 000000000000002a R08: 0000000000000000 R09: ffffffff8aae5a07
R10: 0000000000000050 R11: 0000000000000000 R12: ffff8880000a002a
R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000ef94b6c1
FS:  00007f420328e700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c000203000 CR3: 00000000a2570000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 writeb arch/x86/include/asm/io.h:65 [inline]
 vga16fb_fillrect+0x9c0/0x193b drivers/video/fbdev/vga16fb.c:923
 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x1d5/0x230 drivers/video/fbdev/core/fbcon.c:1381
 fbcon_do_set_font+0x7e2/0x950 drivers/video/fbdev/core/fbcon.c:2614
 fbcon_set_font+0x767/0x8b0 drivers/video/fbdev/core/fbcon.c:2706
 con_font_set drivers/tty/vt/vt.c:4571 [inline]
 con_font_op+0xd25/0x1110 drivers/tty/vt/vt.c:4636
 vt_ioctl+0x1180/0x2670 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb29
Code: Bad RIP value.
RSP: 002b:00007f420328dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004ea260 RCX: 000000000045cb29
RDX: 00000000200002c0 RSI: 0000000000004b61 RDI: 0000000000000004
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000042f R14: 00000000004c7031 R15: 00007f420328e6d4

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Maintainers
ci-upstream-kasan-gce-root	2020/07/07 15:41	upstream	7cc2a8ea	51095195	.config	log	report	ebiggers@google.com, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net, sam@ravnborg.org
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
ci-upstream-linux-next-kasan-gce-root	2020/06/25 10:13	linux-next	e7b08814	54566aff	.config	log	report	ebiggers@google.com, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net, sam@ravnborg.org