INFO: task syz-executor.2:12339 blocked for more than 143 seconds. Not tainted 5.6.0-rc6-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28568 12339 9837 0x20024006 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4154 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4213 __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+0x2da/0x850 fs/file_table.c:280 task_work_run+0x13f/0x1b0 kernel/task_work.c:113 get_signal+0x2054/0x24e0 kernel/signal.c:2533 do_signal+0x7e/0x13f0 arch/x86/kernel/signal.c:813 exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:278 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:352 [inline] do_fast_syscall_32+0xbef/0xe8f arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 INFO: task syz-executor.5:12358 blocked for more than 143 seconds. Not tainted 5.6.0-rc6-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28704 12358 9848 0x20024004 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4154 schedule_timeout+0x6db/0xba0 kernel/time/timer.c:1871 __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:2289 do_fb_ioctl+0x335/0x7d0 drivers/video/fbdev/core/fbmem.c:1106 fb_compat_ioctl+0x305/0xc50 drivers/video/fbdev/core/fbmem.c:1315 __do_compat_sys_ioctl fs/ioctl.c:857 [inline] __se_compat_sys_ioctl fs/ioctl.c:808 [inline] __ia32_compat_sys_ioctl+0x23d/0x2b0 fs/ioctl.c:808 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x270/0xe8f arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 Showing all locks held in the system: 1 lock held by khungtaskd/1120: #0: ffffffff897accc0 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5331 1 lock held by rsyslogd/9696: #0: ffff8880a7dc28a0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:826 2 locks held by getty/9786: #0: ffff8880a19f3090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017532e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9787: #0: ffff88809b219090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017cb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9788: #0: ffff8880a73b1090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017db2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9789: #0: ffff8880a015c090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9790: #0: ffff8880a6343090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc9000174b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9791: #0: ffff8880a2030090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9792: #0: ffff88809e94b090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc9000172b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.2/12339: #0: ffff888218c2d070 (&fb_info->lock){+.+.}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff888218c2d070 (&fb_info->lock){+.+.}, at: fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 2 locks held by syz-executor.2/12340: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1120 Comm: khungtaskd Not tainted 5.6.0-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+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+0x357/0x430 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: 12340 Comm: syz-executor.2 Not tainted 5.6.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__sanitizer_cov_trace_cmp4+0x0/0x20 kernel/kcov.c:248 Code: b6 d6 40 0f b6 f7 31 ff eb 80 48 8b 0c 24 0f b7 d6 0f b7 f7 bf 02 00 00 00 e9 6c ff ff ff 66 90 66 2e 0f 1f 84 00 00 00 00 00 <48> 8b 0c 24 89 f2 89 fe bf 04 00 00 00 e9 4e ff ff ff 0f 1f 40 00 RSP: 0018:ffffc90004ed74b0 EFLAGS: 00000286 RAX: 0000000000040000 RBX: 0000000000000050 RCX: ffffc9000e3b4000 RDX: 0000000000040000 RSI: 000000000000004d RDI: 0000000000000050 RBP: 000000000000004d R08: ffff88805b520640 R09: ffffed104318275c R10: ffffed104318275b R11: ffff888218c13adf R12: ffff8880000a004d R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000efb9e0db FS: 0000000000000000(0000) GS:ffff8880ae600000(0063) knlGS:00000000f5d03b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000000a4e65000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vga16fb_fillrect+0x9da/0x1960 drivers/video/fbdev/vga16fb.c:922 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins+0x1de/0x240 drivers/video/fbdev/core/fbcon.c:1379 fbcon_switch+0xd1b/0x1740 drivers/video/fbdev/core/fbcon.c:2361 redraw_screen+0x2a8/0x770 drivers/tty/vt/vt.c:1008 fbcon_modechanged+0x5bd/0x780 drivers/video/fbdev/core/fbcon.c:2998 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3045 fb_set_var+0xad0/0xd40 drivers/video/fbdev/core/fbmem.c:1056 do_fb_ioctl+0x390/0x7d0 drivers/video/fbdev/core/fbmem.c:1109 fb_compat_ioctl+0x305/0xc50 drivers/video/fbdev/core/fbmem.c:1315 __do_compat_sys_ioctl fs/ioctl.c:857 [inline] __se_compat_sys_ioctl fs/ioctl.c:808 [inline] __ia32_compat_sys_ioctl+0x23d/0x2b0 fs/ioctl.c:808 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x270/0xe8f arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139