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: 53d, last: 32d

similar bugs (1):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
linux-4.19	INFO: task hung in con_install			1	23d	23d	0/1	upstream: reported on 2020/01/30 01:06

Sample crash report:

INFO: task syz-executor.1:26395 blocked for more than 143 seconds.
      Not tainted 5.5.0-rc7-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D28592 26395  10942 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
 __down_common kernel/locking/semaphore.c:220 [inline]
 __down+0x176/0x2c0 kernel/locking/semaphore.c:237
 down+0x64/0x90 kernel/locking/semaphore.c:61
 console_lock+0x29/0x80 kernel/printk/printk.c:2289
 con_install+0x4a/0x410 drivers/tty/vt/vt.c:3228
 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline]
 tty_init_dev drivers/tty/tty_io.c:1341 [inline]
 tty_init_dev+0xf9/0x470 drivers/tty/tty_io.c:1318
 tty_open_by_driver drivers/tty/tty_io.c:1987 [inline]
 tty_open+0x4a5/0xbb0 drivers/tty/tty_io.c:2035
 chrdev_open+0x245/0x6b0 fs/char_dev.c:414
 do_dentry_open+0x4e6/0x1380 fs/open.c:797
 vfs_open+0xa0/0xd0 fs/open.c:914
 do_last fs/namei.c:3356 [inline]
 path_openat+0x118b/0x3180 fs/namei.c:3473
 do_filp_open+0x1a1/0x280 fs/namei.c:3503
 do_sys_open+0x3fe/0x5d0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1110
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4150e1
Code: cc cc cc cc cc cc cc cc cc 48 83 ec 38 48 89 6c 24 30 48 8d 6c 24 30 64 48 8b 04 25 f8 ff ff ff 48 8b 40 30 48 8b 80 d0 00 00 <00> 48 89 44 24 28 84 00 48 8b 4c 24 58 48 89 ca 48 c1 e9 03 48 c1
RSP: 002b:00007fce368557a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fce368566d4 RCX: 00000000004150e1
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007fce368557d0
RBP: 000000000075bf20 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000064 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000bac R14: 00000000004cc995 R15: 000000000075bf2c

Showing all locks held in the system:
1 lock held by khungtaskd/1114:
 #0: ffffffff899a3dc0 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5333
1 lock held by rsyslogd/10774:
 #0: ffff8880a91d88e0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801
2 locks held by getty/10896:
 #0: ffff8880a93a4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900018ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/10897:
 #0: ffff8880a88ea090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900018eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/10898:
 #0: ffff888094e47090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90001aab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/10899:
 #0: ffff8880969d2090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90001acb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/10900:
 #0: ffff888094e48090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc90001abb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/10901:
 #0: ffff88808ddd5090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc9000188b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/10902:
 #0: ffff888097787090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc9000185b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.2/26205:
2 locks held by syz-executor.1/26395:
 #0: ffffffff89ee94e0 (tty_mutex){+.+.}, at: tty_open_by_driver drivers/tty/tty_io.c:1951 [inline]
 #0: ffffffff89ee94e0 (tty_mutex){+.+.}, at: tty_open+0x3cb/0xbb0 drivers/tty/tty_io.c:2035
 #1: ffff888052116198 (&tty->legacy_mutex){+.+.}, at: tty_lock+0xc7/0x130 drivers/tty/tty_mutex.c:19

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

NMI backtrace for cpu 1
CPU: 1 PID: 1114 Comm: khungtaskd Not tainted 5.5.0-rc7-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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 26205 Comm: syz-executor.2 Not tainted 5.5.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:writeb arch/x86/include/asm/io.h:65 [inline]
RIP: 0010:vga16fb_fillrect+0xa05/0x19b0 drivers/video/fbdev/vga16fb.c:923
Code: 45 31 ff 48 89 45 c8 8d 43 ff 48 83 c0 01 48 89 45 c0 e8 ee ba af fd 31 ff 89 de 45 31 e4 e8 62 bc af fd 85 db 4d 89 f5 74 24 <e8> d6 ba af fd 45 88 7d 00 41 83 c4 01 89 df 49 83 c5 01 44 89 e6
RSP: 0018:ffffc90007e1f6a0 EFLAGS: 00000216
RAX: 0000000000000002 RBX: 0000000000000050 RCX: ffffffff83c53a60
RDX: 0000000000000047 RSI: 0000000000000050 RDI: 0000000000000004
RBP: ffffc90007e1f700 R08: ffff88806bc7e580 R09: fffffbfff14f69e8
R10: fffffbfff14f69e7 R11: ffffffff8a7b4f3b R12: 0000000000000047
R13: ffff8880000a0047 R14: ffff8880000a0000 R15: 0000000000000000
FS:  00007f097acf3700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7fc6aba000 CR3: 0000000098e4d000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bit_clear_margins+0x30b/0x530 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x1e9/0x250 drivers/video/fbdev/core/fbcon.c:1372
 fbcon_do_set_font+0x81f/0x960 drivers/video/fbdev/core/fbcon.c:2604
 fbcon_set_font+0x72e/0x860 drivers/video/fbdev/core/fbcon.c:2696
 con_font_set drivers/tty/vt/vt.c:4538 [inline]
 con_font_op+0xe30/0x1270 drivers/tty/vt/vt.c:4603
 vt_ioctl+0xd2e/0x26d0 drivers/tty/vt/vt_ioctl.c:913
 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660
 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: 0033:0x45b349
Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f097acf2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f097acf36d4 RCX: 000000000045b349
RDX: 0000000020000200 RSI: 0000000000004b61 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000003f8 R14: 00000000004c54dd R15: 000000000075bf2c

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
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