NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 INFO: task syz-executor.5:26220 blocked for more than 140 seconds. Not tainted 4.14.176-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28160 26220 6358 0x00000006 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1497 __fput+0x25f/0x790 fs/file_table.c:210 task_work_run+0x113/0x190 kernel/task_work.c:113 get_signal+0x187f/0x1ca0 kernel/signal.c:2234 do_signal+0x7c/0x1690 arch/x86/kernel/signal.c:814 exit_to_usermode_loop+0x159/0x220 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c829 RSP: 002b:00007ff2613e6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000000 RBX: 00000000004e46c0 RCX: 000000000045c829 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002f0 R14: 00000000004c5497 R15: 00007ff2613e76d4 Showing all locks held in the system: 1 lock held by khungtaskd/1057: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544 1 lock held by in:imklog/6033: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0xa6/0xc0 fs/file.c:769 1 lock held by syz-executor.5/26220: #0: (&fb_info->lock){+.+.}, at: [] fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1497 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1057 Comm: khungtaskd Not tainted 4.14.176-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+0x13e/0x194 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x139/0x17e 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 26235 Comm: syz-executor.2 Not tainted 4.14.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff888090ed0440 task.stack: ffff888059598000 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:ffff88805959f3c8 EFLAGS: 00000246 RAX: ffff888090ed0440 RBX: ffff8880000a0050 RCX: ffffc9000a4d9000 RDX: 0000000000000000 RSI: ffffffff831eabd3 RDI: ffff88805959f480 RBP: 0000000000000050 R08: 000000000000ffff R09: ffffed1014b52f6c R10: ffffed1014b52f6b R11: ffff8880a5a97b5f R12: ffff8880000a0016 R13: 0000000000000000 R14: 00000000e51a6300 R15: 000000000000004f FS: 00007f6357c6e700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f59dd5c7740 CR3: 00000000a5812000 CR4: 00000000001426f0 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+0x285/0x310 drivers/video/fbdev/core/fbcon.c:1320 fbcon_switch+0xcdf/0x1780 drivers/video/fbdev/core/fbcon.c:2302 redraw_screen+0x331/0x770 drivers/tty/vt/vt.c:689 fbcon_modechanged+0x59d/0x890 drivers/video/fbdev/core/fbcon.c:2949 fbcon_event_notify+0x11a/0x1746 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/0x940 drivers/video/fbdev/core/fbmem.c:1127 fb_ioctl+0xdd/0x130 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+0x42/0xb7 RIP: 0033:0x45c829 RSP: 002b:00007f6357c6dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004e46c0 RCX: 000000000045c829 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002f0 R14: 00000000004c5497 R15: 00007f6357c6e6d4 Code: e6 bf fe 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 1b a7 a7 7e 81 e2 00 01 1f 00 75 0b <8b> 90 50 13 00 00 83 fa 01 74 01 c3 48 8b 34 24 48 8b 88 58 13