INFO: task syz-executor.1:10887 blocked for more than 143 seconds. Not tainted 5.8.0-rc6-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28704 10887 6968 0x00004004 Call Trace: context_switch kernel/sched/core.c:3458 [inline] __schedule+0x91f/0x2250 kernel/sched/core.c:4215 schedule+0xd0/0x2a0 kernel/sched/core.c:4290 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4349 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x3e2/0x10d0 kernel/locking/mutex.c:1103 lock_fb_info include/linux/fb.h:637 [inline] fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x501/0x1290 fs/open.c:828 do_open fs/namei.c:3243 [inline] path_openat+0x1bb9/0x2750 fs/namei.c:3360 do_filp_open+0x17e/0x3c0 fs/namei.c:3387 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179 do_sys_open fs/open.c:1195 [inline] __do_sys_openat fs/open.c:1209 [inline] __se_sys_openat fs/open.c:1204 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1204 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c1d9 Code: Bad RIP value. RSP: 002b:00007f84c48ebc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000020f00 RCX: 000000000045c1d9 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000078bf48 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c R13: 00007ffe27e2164f R14: 00007f84c48ec9c0 R15: 000000000078bf0c Showing all locks held in the system: 1 lock held by khungtaskd/1154: #0: ffffffff89bc11c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779 1 lock held by in:imklog/6502: #0: ffff8880953143b0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 2 locks held by syz-executor.0/10878: 1 lock held by syz-executor.1/10887: #0: ffff8880a3aff078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff8880a3aff078 (&fb_info->lock){+.+.}-{3:3}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1154 Comm: khungtaskd Not tainted 5.8.0-rc6-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+0x18f/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xd7d/0x1000 kernel/hung_task.c:295 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 10878 Comm: syz-executor.0 Not tainted 5.8.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__sanitizer_cov_trace_pc+0x45/0x60 kernel/kcov.c:202 Code: f6 c4 01 74 35 8b 82 04 14 00 00 85 c0 74 2b 8b 82 e0 13 00 00 83 f8 02 75 20 48 8b 8a e8 13 00 00 8b 92 e4 13 00 00 48 8b 01 <48> 83 c0 01 48 39 c2 76 07 48 89 34 c1 48 89 01 c3 66 2e 0f 1f 84 RSP: 0018:ffffc90008caf080 EFLAGS: 00000246 RAX: 000000000003ffff RBX: 0000000000000050 RCX: ffffc900061d9000 RDX: 0000000000040000 RSI: ffffffff83c67050 RDI: 0000000000000004 RBP: 0000000000000037 R08: 0000000000000001 R09: ffff8880a3af88df R10: 0000000000000050 R11: 0000000000000000 R12: ffff8880000a0037 R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000f277eb2c FS: 00007f13940ce700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6e32dee000 CR3: 000000005bee8000 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+0x9c0/0x193b drivers/video/fbdev/vga16fb.c:923 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins+0x1d5/0x230 drivers/video/fbdev/core/fbcon.c:1381 fbcon_switch+0xb6e/0x16c0 drivers/video/fbdev/core/fbcon.c:2363 redraw_screen+0x2ae/0x770 drivers/tty/vt/vt.c:1015 fbcon_modechanged+0x575/0x710 drivers/video/fbdev/core/fbcon.c:3001 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3048 fb_set_var+0xae8/0xd60 drivers/video/fbdev/core/fbmem.c:1056 fbcon_switch+0x52c/0x16c0 drivers/video/fbdev/core/fbcon.c:2296 redraw_screen+0x2ae/0x770 drivers/tty/vt/vt.c:1015 fbcon_modechanged+0x575/0x710 drivers/video/fbdev/core/fbcon.c:3001 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3048 fb_set_var+0xae8/0xd60 drivers/video/fbdev/core/fbmem.c:1056 do_fb_ioctl+0x33f/0x6c0 drivers/video/fbdev/core/fbmem.c:1109 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1185 vfs_ioctl fs/ioctl.c:48 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:753 __do_sys_ioctl fs/ioctl.c:762 [inline] __se_sys_ioctl fs/ioctl.c:760 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c1d9 Code: Bad RIP value. RSP: 002b:00007f13940cdc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000000d440 RCX: 000000000045c1d9 RDX: 00000000200001c0 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c R13: 00007ffdb41147df R14: 00007f13940ce9c0 R15: 000000000078bf0c