syzbot


INFO: task hung in lock_fb_info

Status: auto-closed as invalid on 2020/10/12 17:28
Reported-by: syzbot+8f1f5cf18a9934bcb873@syzkaller.appspotmail.com
First crash: 854d, last: 740d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in lock_fb_info 5 785d 895d 0/1 auto-closed as invalid on 2020/08/28 16:48

Sample crash report:
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=102 sclass=netlink_route_socket pid=24255 comm=syz-executor.2
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=102 sclass=netlink_route_socket pid=24255 comm=syz-executor.2
INFO: task syz-executor.4:24212 blocked for more than 140 seconds.
      Not tainted 4.14.184-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D28816 24212   6348 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x8a6/0x1d70 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x5f0/0x1430 kernel/locking/mutex.c:893
 lock_fb_info+0x1a/0x70 drivers/video/fbdev/core/fbmem.c:81
 do_fb_ioctl+0x1e8/0x840 drivers/video/fbdev/core/fbmem.c:1224
 fb_ioctl+0xda/0x120 drivers/video/fbdev/core/fbmem.c:1242
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ca69
RSP: 002b:00007f1873a20c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e4c00 RCX: 000000000045ca69
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000003
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002e8 R14: 00000000004c563d R15: 00007f1873a216d4
INFO: task syz-executor.4:24217 blocked for more than 140 seconds.
      Not tainted 4.14.184-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D29712 24217   6348 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x8a6/0x1d70 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x5f0/0x1430 kernel/locking/mutex.c:893
 fb_open+0xb7/0x400 drivers/video/fbdev/core/fbmem.c:1468
 chrdev_open+0x1fc/0x540 fs/char_dev.c:423
 do_dentry_open+0x44b/0xec0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0xb68/0x2aa0 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x292/0x3e0 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ca69
RSP: 002b:00007f18739ffc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00000000004f7fc0 RCX: 000000000045ca69
RDX: 0000000000000000 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000007b7 R14: 00000000004ca978 R15: 00007f1873a006d4
INFO: task syz-executor.0:24208 blocked for more than 140 seconds.
      Not tainted 4.14.184-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D29712 24208   6345 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x8a6/0x1d70 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x5f0/0x1430 kernel/locking/mutex.c:893
 fb_open+0xb7/0x400 drivers/video/fbdev/core/fbmem.c:1468
 chrdev_open+0x1fc/0x540 fs/char_dev.c:423
 do_dentry_open+0x44b/0xec0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0xb68/0x2aa0 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x292/0x3e0 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ca69
RSP: 002b:00007f253763bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00000000004f7fc0 RCX: 000000000045ca69
RDX: 0000000000000000 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000007b7 R14: 00000000004ca978 R15: 00007f253763c6d4

Showing all locks held in the system:
1 lock held by khungtaskd/1057:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8146c8d0>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by in:imklog/5969:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff8191e4e6>] __fdget_pos+0xa6/0xc0 fs/file.c:769
1 lock held by syz-executor.4/24212:
 #0:  (&fb_info->lock){+.+.}, at: [<ffffffff8317deaa>] lock_fb_info+0x1a/0x70 drivers/video/fbdev/core/fbmem.c:81
1 lock held by syz-executor.4/24217:
 #0:  (&fb_info->lock){+.+.}, at: [<ffffffff83182237>] fb_open+0xb7/0x400 drivers/video/fbdev/core/fbmem.c:1468
1 lock held by syz-executor.0/24208:
 #0:  (&fb_info->lock){+.+.}, at: [<ffffffff83182237>] fb_open+0xb7/0x400 drivers/video/fbdev/core/fbmem.c:1468

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

NMI backtrace for cpu 0
CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5e2/0xb80 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 24207 Comm: syz-executor.4 Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880562885c0 task.stack: ffff888025540000
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x1d/0x50 kernel/kcov.c:67
RSP: 0018:ffff8880255473d8 EFLAGS: 00000246
RAX: ffff8880562885c0 RBX: ffff8880000a0050 RCX: ffffc900080eb000
RDX: 0000000000000000 RSI: ffffffff831f9ef3 RDI: ffff888025547490
RBP: 0000000000000050 R08: 000000000000ffff R09: ffffed104322c0fc
R10: ffffed104322c0fb R11: ffff8882191607df R12: ffff8880000a0028
R13: 0000000000000000 R14: 00000000e15bbcd5 R15: 000000000000004f
FS:  00007f1873a42700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000073c138 CR3: 00000000964e3000 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+0x943/0x1880 drivers/video/fbdev/vga16fb.c:923
 bit_clear_margins+0x2a4/0x480 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x274/0x300 drivers/video/fbdev/core/fbcon.c:1320
 fbcon_switch+0xc4e/0x1700 drivers/video/fbdev/core/fbcon.c:2302
 redraw_screen+0x332/0x760 drivers/tty/vt/vt.c:689
 fbcon_modechanged+0x552/0x800 drivers/video/fbdev/core/fbcon.c:2949
 fbcon_event_notify+0x11a/0x1750 drivers/video/fbdev/core/fbcon.c:3302
 notifier_call_chain+0x107/0x1a0 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+0x79/0x90 kernel/notifier.c:325
 fb_set_var+0xaad/0xc70 drivers/video/fbdev/core/fbmem.c:1054
 do_fb_ioctl+0x3cc/0x840 drivers/video/fbdev/core/fbmem.c:1127
 fb_ioctl+0xda/0x120 drivers/video/fbdev/core/fbmem.c:1242
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ca69
RSP: 002b:00007f1873a41c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e4fc0 RCX: 000000000045ca69
RDX: 0000000020000080 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002f7 R14: 00000000004c577c R15: 00007f1873a426d4
Code: 26 f2 dd 08 00 00 00 00 e9 be ed ff ff 90 65 48 8b 04 25 40 ee 01 00 48 85 c0 74 1a 65 8b 15 db 47 a7 7e 81 e2 00 01 1f 00 75 0b <8b> 90 58 13 00 00 83 fa 01 74 01 c3 48 8b 34 24 48 8b 88 60 13 

Crashes (5):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/06/14 17:27 linux-4.14.y b850307b279c 2a22c77a .config log report
ci2-linux-4-14 2020/06/10 17:36 linux-4.14.y c6db52a88798 5caaad3a .config log report
ci2-linux-4-14 2020/03/31 11:16 linux-4.14.y 01364dad1d45 c8d1cc20 .config log report
ci2-linux-4-14 2020/03/12 03:12 linux-4.14.y 12cd844a39ed d850e9d0 .config log report
ci2-linux-4-14 2020/02/21 08:54 linux-4.14.y 98db2bf27b9e bd2a74a3 .config log report