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INFO: task hung in fb_open (2)

Status: auto-closed as invalid on 2021/07/05 14:58
Reported-by: syzbot+77e65da8f6bd2704ae3e@syzkaller.appspotmail.com
First crash: 1701d, last: 1701d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in fb_open 1 C done 552 1907d 2161d 0/29 closed as dup on 2020/07/27 23:07
linux-4.19 INFO: task hung in fb_open 1 108 1922d 2160d 0/1 auto-closed as invalid on 2020/11/26 05:30
linux-4.14 INFO: task hung in fb_open 1 C error 241 1865d 2161d 0/1 upstream: reported C repro on 2019/12/03 09:19
upstream INFO: task hung in fb_open (2) fbdev 1 2 1865d 1865d 0/29 auto-closed as invalid on 2020/12/23 12:44
upstream INFO: task hung in fb_open (3) fbdev 1 1 211d 211d 0/29 auto-obsoleted due to no activity on 2025/07/05 02:15

Sample crash report:
ieee802154 phy1 wpan1: encryption failed: -22
ieee802154 phy0 wpan0: encryption failed: -22
ieee802154 phy1 wpan1: encryption failed: -22
ieee802154 phy0 wpan0: encryption failed: -22
ieee802154 phy1 wpan1: encryption failed: -22
INFO: task syz-executor.3:18845 blocked for more than 140 seconds.
      Not tainted 4.19.179-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D29520 18845   8109 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: 0033:0x465f69
Code: Bad RIP value.
RSP: 002b:00007fc194c0c188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465f69
RDX: 0000000000000000 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 00000000004bfa67 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffc2d452e4f R14: 00007fc194c0c300 R15: 0000000000022000

Showing all locks held in the system:
1 lock held by khungtaskd/1567:
 #0: 000000005ad45eae (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/7792:
 #0: 00000000065dc849 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
3 locks held by syz-executor.3/18815:
1 lock held by syz-executor.3/18845:
 #0: 00000000d08503b6 (&fb_info->lock){+.+.}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1457

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

NMI backtrace for cpu 0
CPU: 0 PID: 1567 Comm: khungtaskd Not tainted 4.19.179-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/0x2ef lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1a6/0x1f0 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+0x33f/0x460 kernel/kthread.c:259
 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: 18815 Comm: syz-executor.3 Not tainted 4.19.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__sanitizer_cov_trace_pc+0x27/0x50 kernel/kcov.c:104
Code: 90 90 90 48 8b 34 24 65 48 8b 04 25 80 df 01 00 65 8b 15 4c 7e 9f 7e 81 e2 00 01 1f 00 75 2b 8b 90 60 13 00 00 83 fa 02 75 20 <48> 8b 88 68 13 00 00 8b 80 64 13 00 00 48 8b 11 48 83 c2 01 48 39
RSP: 0018:ffff88805e3172b8 EFLAGS: 00000246
RAX: ffff88809557a4c0 RBX: 0000000000000002 RCX: ffffffff839d57c4
RDX: 0000000000000002 RSI: ffffffff839d57d0 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: ffff8880000a0000
R13: ffff8880000a0000 R14: 0000000000000000 R15: 000000001db6e987
FS:  00007fc194c2d700(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055bcd290b018 CR3: 0000000096e0e000 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+0x9c0/0x1940 drivers/video/fbdev/vga16fb.c:923
 bit_clear_margins+0x2d5/0x4b0 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x1e2/0x350 drivers/video/fbdev/core/fbcon.c:1288
 fbcon_switch+0xf0d/0x1ba0 drivers/video/fbdev/core/fbcon.c:2152
 redraw_screen+0x37d/0x870 drivers/tty/vt/vt.c:1015
 fbcon_modechanged+0x6df/0x930 drivers/video/fbdev/core/fbcon.c:2685
 fbcon_event_notify+0x197/0x1d80 drivers/video/fbdev/core/fbcon.c:3058
 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: 0033:0x465f69
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc194c2d188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465f69
RDX: 0000000020000100 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 00000000004bfa67 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffc2d452e4f R14: 00007fc194c2d300 R15: 0000000000022000

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/03/07 14:57 linux-4.19.y 2cae3e25b706 c599ed12 .config console log report info ci2-linux-4-19 INFO: task hung in fb_open
* Struck through repros no longer work on HEAD.