INFO: task syz-executor.0:3058 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.0 D28360 3058 6838 0x20024004 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_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 __fput+0x33c/0x880 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:135 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:239 [inline] __prepare_exit_to_usermode+0x1e9/0x1f0 arch/x86/entry/common.c:269 __do_fast_syscall_32 arch/x86/entry/common.c:475 [inline] do_fast_syscall_32+0x7f/0x120 arch/x86/entry/common.c:503 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c RIP: 0023:0xf7f3c569 Code: Bad RIP value. RSP: 002b:00000000086afbec EFLAGS: 00000212 ORIG_RAX: 0000000000000006 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000 RDX: 0000000000000004 RSI: 000000000819b620 RDI: 000000000031a089 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/1155: #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/6528: #0: ffff888093464170 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 2 locks held by syz-executor.2/27824: #0: ffff8880a869b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000f542e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/28054: #0: ffff8880a869b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000f542e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/28088: #0: ffff8880a869b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000f542e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/28144: #0: ffff8880a869b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000f542e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.2/7689: #0: ffff8880a869b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000f542e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.2/7735: #0: ffff8880a869b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000f542e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.0/3058: #0: ffff8880a375a078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff8880a375a078 (&fb_info->lock){+.+.}-{3:3}, at: fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 2 locks held by syz-executor.4/3125: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1155 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 3125 Comm: syz-executor.4 Not tainted 5.8.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:write_comp_data+0x78/0x80 kernel/kcov.c:242 Code: 00 00 4e 8d 0c dd 28 00 00 00 4c 39 ce 72 1b 49 83 c0 01 4a 89 7c 08 e0 4e 89 54 08 e8 4a 89 54 08 f0 4a 89 4c d8 20 4c 89 00 0f 1f 80 00 00 00 00 48 8b 0c 24 40 0f b6 d6 40 0f b6 f7 31 ff RSP: 0018:ffffc900080874d8 EFLAGS: 00000297 RAX: 0000000000000002 RBX: 0000000000000010 RCX: ffffffff83c66fe4 RDX: 0000000000000004 RSI: ffff88801035e240 RDI: 0000000000000004 RBP: 0000000000000004 R08: 0000000000000001 R09: ffff888218ed2edf R10: 0000000000000010 R11: 0000000000000000 R12: ffff8880000a0004 R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000cae2bf37 FS: 0000000000000000(0000) GS:ffff8880ae600000(0063) knlGS:00000000f5d11b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00007f410e8f2010 CR3: 0000000056914000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vga16fb_fillrect+0x9d4/0x193b drivers/video/fbdev/vga16fb.c:922 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 do_fb_ioctl+0x33f/0x6c0 drivers/video/fbdev/core/fbmem.c:1109 fb_compat_ioctl+0x175/0xc10 drivers/video/fbdev/core/fbmem.c:1315 __do_compat_sys_ioctl+0x1d3/0x230 fs/ioctl.c:847 do_syscall_32_irqs_on+0x3f/0x60 arch/x86/entry/common.c:428 __do_fast_syscall_32 arch/x86/entry/common.c:475 [inline] do_fast_syscall_32+0x7f/0x120 arch/x86/entry/common.c:503 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c RIP: 0023:0xf7f37569 Code: Bad RIP value. RSP: 002b:00000000f5d110cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000004601 RDX: 0000000020000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000