syzbot

INFO: task syz-executor.0:18324 blocked for more than 143 seconds.
      Not tainted 5.8.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28696 18324   6822 0x20024004
Call Trace:
 context_switch kernel/sched/core.c:3453 [inline]
 __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4178
 schedule+0xd0/0x2a0 kernel/sched/core.c:4253
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4312
 __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_set_user_cmap+0x33d/0x450 drivers/video/fbdev/core/fbcmap.c:288
 do_fb_ioctl+0x66e/0x6c0 drivers/video/fbdev/core/fbmem.c:1128
 fb_getput_cmap drivers/video/fbdev/core/fbmem.c:1239 [inline]
 fb_compat_ioctl+0x551/0xc10 drivers/video/fbdev/core/fbmem.c:1324
 __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: 0023:0xf7f9b569
Code: Bad RIP value.
RSP: 002b:00000000f5d750cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000004605
RDX: 0000000020000040 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor.0:18327 blocked for more than 143 seconds.
      Not tainted 5.8.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28728 18327   6822 0x20020004
Call Trace:
 context_switch kernel/sched/core.c:3453 [inline]
 __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4178
 schedule+0xd0/0x2a0 kernel/sched/core.c:4253
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4312
 __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_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x501/0x1290 fs/open.c:828
 do_open fs/namei.c:3243 [inline]
 path_openat+0x1bb9/0x2750 fs/namei.c:3360
 do_filp_open+0x17e/0x3c0 fs/namei.c:3387
 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179
 do_sys_open fs/open.c:1195 [inline]
 __do_compat_sys_openat fs/open.c:1251 [inline]
 __se_compat_sys_openat fs/open.c:1249 [inline]
 __ia32_compat_sys_openat+0x13f/0x1f0 fs/open.c:1249
 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: 0023:0xf7f9b569
Code: Bad RIP value.
RSP: 002b:00000000f5d540cc EFLAGS: 00000296 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 0000000020000180
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
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/1148:
 #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/6503:
 #0: ffff88809796d6b0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826
2 locks held by syz-executor.0/18317:
1 lock held by syz-executor.0/18324:
 #0: ffff8880a3614078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline]
 #0: ffff8880a3614078 (&fb_info->lock){+.+.}-{3:3}, at: fb_set_user_cmap+0x33d/0x450 drivers/video/fbdev/core/fbcmap.c:288
1 lock held by syz-executor.0/18327:
 #0: ffff8880a3614078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline]
 #0: ffff8880a3614078 (&fb_info->lock){+.+.}-{3:3}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1148 Comm: khungtaskd Not tainted 5.8.0-rc5-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: 18317 Comm: syz-executor.0 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline]
RIP: 0010:write_comp_data+0x13/0x80 kernel/kcov.c:218
Code: 48 8b 80 f8 13 00 00 c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 49 89 f2 65 8b 05 76 49 8e 7e 65 48 8b 34 25 00 ff 01 00 <a9> 00 01 ff 00 74 0f f6 c4 01 74 59 8b 86 04 14 00 00 85 c0 74 4f
RSP: 0018:ffffc900025274d8 EFLAGS: 00000282
RAX: 0000000080000000 RBX: 000000000000000c RCX: ffffffff83c66de4
RDX: 0000000000000008 RSI: ffff88804c1a0240 RDI: 0000000000000004
RBP: 0000000000000008 R08: 0000000000000001 R09: ffff8880a357ac1f
R10: 000000000000000c R11: 0000000000000000 R12: ffff8880000a0008
R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000af38426a
FS:  0000000000000000(0000) GS:ffff8880ae600000(0063) knlGS:00000000f5d96b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007ffedb3fbf27 CR3: 0000000053f46000 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: 0023:0xf7f9b569
Code: Bad RIP value.
RSP: 002b:00000000f5d960cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000004601
RDX: 0000000020000200 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000