INFO: task syz-executor.1:16708 blocked for more than 143 seconds. Not tainted 5.7.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28528 16708 7161 0x00004004 Call Trace: context_switch kernel/sched/core.c:3367 [inline] __schedule+0x805/0xc90 kernel/sched/core.c:4083 schedule+0x188/0x220 kernel/sched/core.c:4158 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4217 __mutex_lock_common+0x129f/0x2fc0 kernel/locking/mutex.c:1033 lock_fb_info include/linux/fb.h:637 [inline] fb_release+0x4a/0x180 drivers/video/fbdev/core/fbmem.c:1447 fb_open+0x3b0/0x3b0 include/linux/fs.h:900 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118 lock_fb_info include/linux/fb.h:637 [inline] fb_release+0x4a/0x180 drivers/video/fbdev/core/fbmem.c:1447 fb_open+0x3b0/0x3b0 include/linux/fs.h:900 __fput+0x2ed/0x750 fs/file_table.c:280 task_work_run+0x147/0x1d0 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:165 [inline] prepare_exit_to_usermode+0x48e/0x600 arch/x86/entry/common.c:196 syscall_return_slowpath+0xf9/0x420 arch/x86/entry/common.c:278 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Showing all locks held in the system: 1 lock held by khungtaskd/1140: #0: ffffffff892e8550 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 net/mptcp/pm_netlink.c:860 1 lock held by in:imklog/6690: #0: ffff88809e297370 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x25d/0x2f0 fs/file.c:826 1 lock held by syz-executor.1/16708: #0: ffff888218808078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff888218808078 (&fb_info->lock){+.+.}-{3:3}, at: fb_release+0x4a/0x180 drivers/video/fbdev/core/fbmem.c:1447 2 locks held by syz-executor.1/16718: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1140 Comm: khungtaskd Not tainted 5.7.0-rc3-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+0x1e9/0x30e lib/dump_stack.c:118 nmi_cpu_backtrace+0x9f/0x180 lib/nmi_backtrace.c:101 arch_trigger_cpumask_backtrace+0x10/0x10 arch/x86/kernel/apic/hw_nmi.c:38 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xd2a/0xd40 kernel/hung_task.c:289 kthread+0x353/0x380 kernel/kthread.c:268 hungtask_pm_notify+0x50/0x50 kernel/hung_task.c:265 kthread_blkcg+0xd0/0xd0 kernel/kthread.c:1247 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: 16718 Comm: syz-executor.1 Not tainted 5.7.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x2e/0x50 kernel/kcov.c:192 Code: 65 48 8b 0c 25 40 1e 02 00 65 8b 15 c8 bc 8e 7e f7 c2 00 01 1f 00 75 2c 8b 91 d8 13 00 00 83 fa 02 75 21 48 8b 91 e0 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 dc 13 00 00 48 39 cf 73 08 48 89 44 f2 RSP: 0018:ffffc90007daf950 EFLAGS: 00000246 RAX: ffffffff83d194b0 RBX: 0000000000000000 RCX: ffff88804cc0a000 RDX: ffffc90005a49000 RSI: 000000000003ffff RDI: 0000000000040000 RBP: 0000000000000048 R08: ffffffff83d1946b R09: ffffffff83d18bdf R10: ffff88804cc0a000 R11: 0000000000000002 R12: 00000000dd72da88 R13: ffff8880000a0008 R14: ffffffffffffffb0 R15: 000000000000004f FS: 00007f49c6f97700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c003436248 CR3: 000000008ed1c000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vga16fb_fillrect+0xfe0/0x13e0 drivers/video/fbdev/vga16fb.c:922 bit_clear_margins+0x37b/0x620 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins drivers/video/fbdev/core/fbcon.c:1381 [inline] fbcon_switch+0x1448/0x1e40 drivers/video/fbdev/core/fbcon.c:2363 redraw_screen+0x4fc/0x16f0 drivers/tty/vt/vt.c:1010 fbcon_modechanged+0x8d5/0xd90 drivers/video/fbdev/core/fbcon.c:3000 fb_set_var+0x822/0xcc0 drivers/video/fbdev/core/fbmem.c:1056 do_fb_ioctl+0x502/0x6f0 drivers/video/fbdev/core/fbmem.c:1109 fb_write+0x540/0x540 drivers/video/fbdev/core/fbmem.c:849 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:771 [inline] __do_sys_ioctl fs/ioctl.c:780 [inline] __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:778 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c829 Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f49c6f96c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004e4740 RCX: 000000000045c829 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000006 RBP: 000000000078c0e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002f0 R14: 00000000004c5497 R15: 00007f49c6f976d4