INFO: task syz-executor.1:13941 blocked for more than 143 seconds. Not tainted 5.5.0-rc7-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29448 13941 8655 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4081 schedule+0x188/0x210 kernel/sched/core.c:4155 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214 __mutex_lock_common+0x11f1/0x2f30 kernel/locking/mutex.c:1033 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118 lock_fb_info include/linux/fb.h:637 [inline] do_fb_ioctl+0x225/0x780 drivers/video/fbdev/core/fbmem.c:1112 fb_ioctl+0xb9/0xf0 drivers/video/fbdev/core/fbmem.c:1180 do_vfs_ioctl+0x6e2/0x19b0 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:749 [inline] __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:754 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b349 Code: 80 00 00 0f 83 b2 00 00 00 48 3d f8 03 00 00 77 7a 48 83 c0 07 48 c1 e8 03 48 3d 81 00 00 00 0f 83 df 00 00 00 48 8d 15 f5 7c <9f> 00 0f b6 04 10 48 83 f8 43 0f 83 c0 00 00 00 48 8d 0d 20 7e 9f RSP: 002b:00007f6f8b2abc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f6f8b2ac6d4 RCX: 000000000045b349 RDX: 0000000020000340 RSI: 0000000000004602 RDI: 0000000000000003 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002c8 R14: 00000000004c3d52 R15: 000000000075bfd4 Showing all locks held in the system: 1 lock held by khungtaskd/1106: #0: ffffffff890d45c0 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 1 lock held by rsyslogd/8525: #0: ffff888096c94360 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x243/0x2e0 fs/file.c:801 2 locks held by getty/8615: #0: ffff888098566090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8616: #0: ffff88809e966090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000186b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8617: #0: ffff888092d03090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000185b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8618: #0: ffff888090438090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000182b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8619: #0: ffff8880a22b2090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000187b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8620: #0: ffff8880a6d37090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000183b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8621: #0: ffff88809af2b090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.1/13935: 1 lock held by syz-executor.1/13941: #0: ffff8880a3c67070 (&fb_info->lock){+.+.}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff8880a3c67070 (&fb_info->lock){+.+.}, at: do_fb_ioctl+0x225/0x780 drivers/video/fbdev/core/fbmem.c:1112 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1106 Comm: khungtaskd Not tainted 5.5.0-rc7-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+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaa/0x190 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x16f/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace+0x17/0x20 include/linux/nmi.h:146 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xd40/0xd60 kernel/hung_task.c:289 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 13935 Comm: syz-executor.1 Not tainted 5.5.0-rc7-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+0x8/0x50 kernel/kcov.c:186 Code: 0b 90 55 48 89 e5 53 48 89 fb e8 13 00 00 00 48 8b 3d 44 13 ce 07 48 89 de e8 44 ca 3b 00 5b 5d c3 cc 55 48 89 e5 48 8b 45 08 <65> 48 8b 0c 25 c0 1d 02 00 65 8b 15 c4 9d 8b 7e f7 c2 00 01 1f 00 RSP: 0018:ffffc900187377e8 EFLAGS: 00000282 RAX: ffffffff83ceaa80 RBX: 0000000000000045 RCX: 0000000000040000 RDX: ffffc90005ec1000 RSI: 000000000003ffff RDI: 0000000000040000 RBP: ffffc900187377e8 R08: ffffffff83ceaa50 R09: ffffffff83cea12a R10: ffff88804f3162c0 R11: 0000000000000002 R12: 000000000000004f R13: ffff8880000a000b R14: 0000000000000000 R15: ffffffffffffffb0 FS: 00007f6f8b2cd700(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f34e9c1958f CR3: 000000009e719000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vga16fb_fillrect+0x1040/0x1470 drivers/video/fbdev/vga16fb.c:922 bit_clear_margins+0x368/0x620 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins drivers/video/fbdev/core/fbcon.c:1372 [inline] fbcon_switch+0x1504/0x1f10 drivers/video/fbdev/core/fbcon.c:2354 redraw_screen+0x56e/0x1830 drivers/tty/vt/vt.c:997 fbcon_modechanged+0x810/0xdf0 drivers/video/fbdev/core/fbcon.c:2991 fbcon_update_vcs+0x31/0x40 drivers/video/fbdev/core/fbcon.c:3038 fb_set_var+0x8f5/0xdc0 drivers/video/fbdev/core/fbmem.c:1051 do_fb_ioctl+0x55e/0x780 drivers/video/fbdev/core/fbmem.c:1104 fb_ioctl+0xb9/0xf0 drivers/video/fbdev/core/fbmem.c:1180 do_vfs_ioctl+0x6e2/0x19b0 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:749 [inline] __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:754 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b349 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:00007f6f8b2ccc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f6f8b2cd6d4 RCX: 000000000045b349 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002cd R14: 00000000004c3dc6 R15: 000000000075bf2c