INFO: task syz-executor.4:17535 blocked for more than 143 seconds. Not tainted 5.6.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D27520 17535 7382 0x00004006 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4168 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4227 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103 lock_fb_info include/linux/fb.h:637 [inline] fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 __fput+0x2e9/0x860 fs/file_table.c:280 task_work_run+0xf4/0x1b0 kernel/task_work.c:123 get_signal+0x2058/0x24e0 kernel/signal.c:2533 do_signal+0x81/0x2240 arch/x86/kernel/signal.c:784 exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c849 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:00007f5b78874c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000000 RBX: 00007f5b788756d4 RCX: 000000000045c849 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002ee R14: 00000000004c547c R15: 000000000076bf0c INFO: task syz-executor.2:17663 blocked for more than 143 seconds. Not tainted 5.6.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28408 17663 7304 0x00000004 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4168 schedule_timeout+0x55b/0x850 kernel/time/timer.c:1874 __down_common kernel/locking/semaphore.c:220 [inline] __down+0x176/0x2c0 kernel/locking/semaphore.c:237 down+0x57/0x80 kernel/locking/semaphore.c:61 console_lock+0x25/0x80 kernel/printk/printk.c:2286 do_fb_ioctl+0x335/0x6e0 drivers/video/fbdev/core/fbmem.c:1106 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1185 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c849 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:00007f5c90484c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f5c904856d4 RCX: 000000000045c849 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000004 RBP: 000000000076c040 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002ee R14: 00000000004c547c R15: 000000000076c04c Showing all locks held in the system: 2 locks held by kworker/u4:0/7: 1 lock held by khungtaskd/1132: #0: ffffffff899bb200 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5743 1 lock held by in:imklog/6708: #0: ffff8880953ced70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 1 lock held by syz-executor.4/17535: #0: ffff8880a35a9078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff8880a35a9078 (&fb_info->lock){+.+.}-{3:3}, at: fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 2 locks held by syz-executor.2/17651: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1132 Comm: khungtaskd Not tainted 5.6.0-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+0x188/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xa8c/0x1010 kernel/hung_task.c:289 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 17651 Comm: syz-executor.2 Not tainted 5.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50 kernel/kcov.c:186 Code: 00 00 00 00 e9 e8 e7 ff ff cc 65 48 8b 04 25 00 1f 02 00 48 8b 80 f0 13 00 00 c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 <65> 48 8b 04 25 00 1f 02 00 65 8b 15 08 3e 8f 7e 81 e2 00 01 1f 00 RSP: 0018:ffffc9001db87590 EFLAGS: 00000212 RAX: 0000000000000002 RBX: 0000000000000050 RCX: ffffffff83ba4c3a RDX: 000000000000003a RSI: 0000000000000050 RDI: 0000000000000004 RBP: 000000000000003a R08: ffff8880131da200 R09: ffffed1014756264 R10: ffff8880a3ab131f R11: ffffed1014756263 R12: ffff8880000a003a R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000f96df890 FS: 00007f5c904c7700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055b23cb56110 CR3: 00000000221dd000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000004 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: writeb arch/x86/include/asm/io.h:65 [inline] vga16fb_fillrect+0x9c6/0x1960 drivers/video/fbdev/vga16fb.c:923 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins+0x1de/0x240 drivers/video/fbdev/core/fbcon.c:1378 fbcon_switch+0xd21/0x1740 drivers/video/fbdev/core/fbcon.c:2360 redraw_screen+0x2ae/0x770 drivers/tty/vt/vt.c:1009 fbcon_modechanged+0x5c3/0x790 drivers/video/fbdev/core/fbcon.c:2997 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3044 fb_set_var+0xad0/0xd40 drivers/video/fbdev/core/fbmem.c:1056 do_fb_ioctl+0x390/0x6e0 drivers/video/fbdev/core/fbmem.c:1109 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1185 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c849 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:00007f5c904c6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f5c904c76d4 RCX: 000000000045c849 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000004 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002ee R14: 00000000004c547c R15: 000000000076bf0c