INFO: task syz-executor.4:14230 blocked for more than 143 seconds. Not tainted 5.7.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D27488 14230 7349 0x00000004 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4163 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4222 __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+0x33e/0x880 fs/file_table.c:280 task_work_run+0xf4/0x1b0 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165 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: 0033:0x416421 Code: 48 89 6c 24 58 48 8d 6c 24 58 48 8b 94 24 98 00 00 00 48 f7 c2 1f 00 00 00 0f 85 3d 03 00 00 48 8b 9c 24 88 00 00 00 48 8b 84 <24> 90 00 00 00 48 39 c3 0f 84 eb 01 00 00 48 85 db 0f 84 98 02 00 RSP: 002b:00007ffc9cb4f5e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000416421 RDX: 0000000000000000 RSI: 0000000000000601 RDI: 0000000000000006 RBP: 0000000000000001 R08: 000000001affc601 R09: 000000001affc605 R10: 00007ffc9cb4f6c0 R11: 0000000000000293 R12: 000000000076c900 R13: 000000000076c900 R14: 000000000007e146 R15: 000000000076bf0c Showing all locks held in the system: 1 lock held by khungtaskd/1129: #0: ffffffff899bed00 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5754 1 lock held by in:imklog/6917: #0: ffff8880a76c70f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 1 lock held by syz-executor.4/14230: #0: ffff8880a3581078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff8880a3581078 (&fb_info->lock){+.+.}-{3:3}, at: fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 2 locks held by syz-executor.4/14240: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1129 Comm: khungtaskd Not tainted 5.7.0-rc1-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: 14240 Comm: syz-executor.4 Not tainted 5.7.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:vga16fb_fillrect+0x9d3/0x1960 drivers/video/fbdev/vga16fb.c:922 Code: 08 e8 c1 d4 af fd 31 ff 89 de 31 ed e8 26 d6 af fd 85 db 4d 89 ec 74 22 e8 aa d4 af fd 45 88 34 24 83 c5 01 89 df 49 83 c4 01 <89> ee e8 86 d5 af fd 39 eb 75 e3 4c 03 6c 24 08 e8 88 d4 af fd 44 RSP: 0018:ffffc90004c17070 EFLAGS: 00000286 RAX: 0000000000040000 RBX: 0000000000000050 RCX: ffffc90011b97000 RDX: 0000000000040000 RSI: ffffffff83c35f56 RDI: 0000000000000050 RBP: 0000000000000044 R08: ffff88804969c200 R09: ffffed10432440cc R10: ffff88821922065f R11: ffffed10432440cb R12: ffff8880000a0044 R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000efac9fcd FS: 00007fbbb4600700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb9536e5000 CR3: 00000000a8b29000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins+0x1de/0x240 drivers/video/fbdev/core/fbcon.c:1381 fbcon_switch+0xd21/0x1740 drivers/video/fbdev/core/fbcon.c:2363 redraw_screen+0x2ae/0x770 drivers/tty/vt/vt.c:1009 fbcon_modechanged+0x5c3/0x790 drivers/video/fbdev/core/fbcon.c:3000 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3047 fb_set_var+0xad0/0xd40 drivers/video/fbdev/core/fbmem.c:1056 fbcon_switch+0x526/0x1740 drivers/video/fbdev/core/fbcon.c:2296 redraw_screen+0x2ae/0x770 drivers/tty/vt/vt.c:1009 fbcon_modechanged+0x5c3/0x790 drivers/video/fbdev/core/fbcon.c:3000 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3047 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: 0033:0x45c889 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:00007fbbb45ffc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fbbb46006d4 RCX: 000000000045c889 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000008 RBP: 000000000076bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002f0 R14: 00000000004c54e4 R15: 000000000076bfac