INFO: task hung in fb

INFO: task hung in fb_open
Status: auto-closed as invalid on 2020/11/26 05:30
Reported-by: syzbot+bbf1fc109bb816889956@syzkaller.appspotmail.com
First crash: 453d, last: 215d

similar bugs (3):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	INFO: task hung in fb_open	C	done		552	199d	453d	0/21	closed as dup on 2020/07/27 23:07
linux-4.14	INFO: task hung in fb_open	C		error	241	158d	454d	0/1	upstream: reported C repro on 2019/12/03 09:19
upstream	INFO: task hung in fb_open (2)				2	158d	158d	0/21	auto-closed as invalid on 2020/12/23 12:44

Sample crash report:

audit: type=1804 audit(1595997961.645:189): pid=10533 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op=invalid_pcr cause=open_writers comm="syz-executor.2" name="/root/syzkaller-testdir098160280/syzkaller.mNxdkd/2134/cgroup.controllers" dev="sda1" ino=16309 res=1
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.5'.
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
INFO: task syz-executor.4:10484 blocked for more than 140 seconds.
      Not tainted 4.19.134-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D29336 10484   6867 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2828 [inline]
 __schedule+0x887/0x2040 kernel/sched/core.c:3517
 schedule+0x8d/0x1b0 kernel/sched/core.c:3561
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0x647/0x1260 kernel/locking/mutex.c:1072
 fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1457
 chrdev_open+0x266/0x770 fs/char_dev.c:423
 do_dentry_open+0x4aa/0x1160 fs/open.c:796
 do_last fs/namei.c:3421 [inline]
 path_openat+0x793/0x2df0 fs/namei.c:3537
 do_filp_open+0x18c/0x3f0 fs/namei.c:3567
 do_sys_open+0x3b3/0x520 fs/open.c:1085
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c369
Code: 64 00 00 00 0f 11 44 24 38 48 83 c9 01 48 89 4c 24 48 e8 3a db ff ff 48 8b 44 24 50 e9 8c fe ff ff 48 8b 8c 24 a8 01 00 00 48 <8b> 94 24 b0 01 00 00 48 8b 9c 24 c8 01 00 00 e9 00 fe ff ff ba 01
RSP: 002b:00007f5232180c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000021000 RCX: 000000000045c369
RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c
RBP: 000000000078bfe8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bfac
R13: 00007ffd62c5181f R14: 00007f52321819c0 R15: 000000000078bfac

Showing all locks held in the system:
1 lock held by khungtaskd/1083:
 #0: 000000002a6300df (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/6142:
 #0: 000000007584211a (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
2 locks held by agetty/6139:
 #0: 000000004f8c6fbc (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
 #1: 00000000d2320961 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1950 drivers/tty/n_tty.c:2154
2 locks held by agetty/6141:
 #0: 00000000969fb3dc (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
 #1: 000000004644b7bd (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1950 drivers/tty/n_tty.c:2154
3 locks held by syz-executor.4/10466:
1 lock held by syz-executor.4/10484:
 #0: 00000000c05bd37c (&fb_info->lock){+.+.}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1457

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

NMI backtrace for cpu 0
CPU: 0 PID: 1083 Comm: khungtaskd Not tainted 4.19.134-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+0x1fc/0x2fe lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
 watchdog+0x991/0xe60 kernel/hung_task.c:287
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 10466 Comm: syz-executor.4 Not tainted 4.19.134-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:vga16fb_fillrect+0x9c4/0x1940 drivers/video/fbdev/vga16fb.c:922
Code: 44 24 10 45 31 f6 48 89 04 24 e8 e7 cb e3 fd 31 ff 89 de 31 ed e8 4c cd e3 fd 85 db 4d 89 ec 74 22 e8 d0 cb e3 fd 45 88 34 24 <83> c5 01 89 df 49 83 c4 01 89 ee e8 ac cc e3 fd 39 eb 75 e3 89 d8
RSP: 0018:ffff88803f8972c0 EFLAGS: 00000246
RAX: 0000000000040000 RBX: 0000000000000050 RCX: ffffc9000e3f6000
RDX: 0000000000040000 RSI: ffffffff8385e370 RDI: 0000000000000004
RBP: 0000000000000025 R08: 0000000000000001 R09: 0000000000000050
R10: 0000000000000004 R11: 0000000000000000 R12: ffff8880000a0025
R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000efcdb6f1
FS:  00007f52321a2700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc8ca63d000 CR3: 000000009686d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x1e2/0x350 drivers/video/fbdev/core/fbcon.c:1342
 fbcon_switch+0x1038/0x1d26 drivers/video/fbdev/core/fbcon.c:2324
 redraw_screen+0x37d/0x870 drivers/tty/vt/vt.c:1015
 fbcon_modechanged+0x6e9/0x9f0 drivers/video/fbdev/core/fbcon.c:2972
 fbcon_event_notify+0x197/0x1d80 drivers/video/fbdev/core/fbcon.c:3347
 notifier_call_chain+0xc0/0x230 kernel/notifier.c:93
 __blocking_notifier_call_chain kernel/notifier.c:317 [inline]
 __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 blocking_notifier_call_chain+0x85/0xa0 kernel/notifier.c:325
 fb_set_var+0xc51/0xe20 drivers/video/fbdev/core/fbmem.c:1042
 do_fb_ioctl+0x3cf/0xb50 drivers/video/fbdev/core/fbmem.c:1115
 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1230
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c369
Code: 8d 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 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f52321a1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000d540 RCX: 000000000045c369
RDX: 0000000020000200 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffd62c5181f R14: 00007f52321a29c0 R15: 000000000078bf0c

Crashes (108):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci2-linux-4-19	2020/07/29 04:48	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/29 01:37	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/28 23:51	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/28 16:21	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/28 10:10	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/28 06:55	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/28 06:25	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/28 03:09	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/27 23:35	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/27 18:22	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/25 03:55	linux-4.19.y	20b3a3df	0a13649c	.config	log	report
ci2-linux-4-19	2020/07/24 19:59	linux-4.19.y	20b3a3df	554af388	.config	log	report
ci2-linux-4-19	2020/07/18 13:50	linux-4.19.y	17a87580	9c812472	.config	log	report
ci2-linux-4-19	2020/07/16 07:21	linux-4.19.y	17a87580	ada108d0	.config	log	report
ci2-linux-4-19	2020/07/15 06:21	linux-4.19.y	dce0f886	ada108d0	.config	log	report
ci2-linux-4-19	2020/07/05 11:09	linux-4.19.y	399849e4	24d7f505	.config	log	report
ci2-linux-4-19	2020/07/05 08:27	linux-4.19.y	399849e4	24d7f505	.config	log	report
ci2-linux-4-19	2020/06/29 03:38	linux-4.19.y	a39e7545	a2cdad9d	.config	log	report
ci2-linux-4-19	2020/06/23 04:19	linux-4.19.y	b3a99fd3	1afe1535	.config	log	report
ci2-linux-4-19	2020/06/22 06:10	linux-4.19.y	3fc89857	eabcced4	.config	log	report
ci2-linux-4-19	2020/06/18 15:58	linux-4.19.y	3fc89857	3ea11d3f	.config	log	report
ci2-linux-4-19	2020/06/16 10:15	linux-4.19.y	3fc89857	baca2611	.config	log	report
ci2-linux-4-19	2020/06/13 06:30	linux-4.19.y	3fc89857	f4724dd3	.config	log	report
ci2-linux-4-19	2020/06/12 21:18	linux-4.19.y	3fc89857	3036d6fd	.config	log	report
ci2-linux-4-19	2020/06/09 08:42	linux-4.19.y	106fa147	0d60b78a	.config	log	report
ci2-linux-4-19	2020/06/04 08:29	linux-4.19.y	4707d8e5	b0d1c0d5	.config	log	report
ci2-linux-4-19	2020/06/02 02:23	linux-4.19.y	2d16cf48	a0331e89	.config	log	report
ci2-linux-4-19	2020/05/31 10:28	linux-4.19.y	2d16cf48	a0331e89	.config	log	report
ci2-linux-4-19	2020/05/31 06:21	linux-4.19.y	2d16cf48	6f3e1c7c	.config	log	report
ci2-linux-4-19	2020/05/28 04:59	linux-4.19.y	2d16cf48	9072c126	.config	log	report
ci2-linux-4-19	2020/05/27 22:27	linux-4.19.y	2d16cf48	9072c126	.config	log	report
ci2-linux-4-19	2020/05/27 17:02	linux-4.19.y	2d16cf48	9072c126	.config	log	report
ci2-linux-4-19	2020/05/13 02:28	linux-4.19.y	033c4ea4	a44eb8f7	.config	log	report
ci2-linux-4-19	2020/05/12 20:35	linux-4.19.y	033c4ea4	a44eb8f7	.config	log	report
ci2-linux-4-19	2020/05/08 15:12	linux-4.19.y	84920cc7	fe4122c3	.config	log	report
ci2-linux-4-19	2020/05/07 16:12	linux-4.19.y	84920cc7	98cbd87b	.config	log	report
ci2-linux-4-19	2020/05/07 04:20	linux-4.19.y	84920cc7	4618eb2d	.config	log	report
ci2-linux-4-19	2020/05/06 11:06	linux-4.19.y	84920cc7	35b8eb30	.config	log	report
ci2-linux-4-19	2020/05/06 07:15	linux-4.19.y	84920cc7	35b8eb30	.config	log	report
ci2-linux-4-19	2020/05/05 23:05	linux-4.19.y	fdc07232	4b76dd25	.config	log	report
ci2-linux-4-19	2020/05/04 21:03	linux-4.19.y	fdc07232	9941337c	.config	log	report
ci2-linux-4-19	2020/05/03 01:19	linux-4.19.y	fdc07232	5457883a	.config	log	report
ci2-linux-4-19	2020/05/02 02:28	linux-4.19.y	76567537	bc734e7a	.config	log	report
ci2-linux-4-19	2020/04/30 07:13	linux-4.19.y	76567537	2dd552a5	.config	log	report
ci2-linux-4-19	2020/04/28 00:35	linux-4.19.y	7edd66cf	0ce7569e	.config	log	report
ci2-linux-4-19	2020/04/26 09:02	linux-4.19.y	7edd66cf	0ce7569e	.config	log	report
ci2-linux-4-19	2019/12/04 11:17	linux-4.19.y	174651bd	0ecb9746	.config	log	report