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INFO: task hung in con_write (2)

Status: auto-closed as invalid on 2020/10/13 06:51
Subsystems: serial
[Documentation on labels]
First crash: 1437d, last: 1389d
▶ ▼ Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in con_write 2 1417d 1484d 0/1 auto-closed as invalid on 2020/10/15 09:20
upstream INFO: task hung in con_write serial 1 1602d 1602d 0/26 auto-closed as invalid on 2020/03/14 17:26
linux-4.14 INFO: task hung in con_write 1 1448d 1448d 0/1 auto-closed as invalid on 2020/09/14 21:41

Sample crash report:
INFO: task syz-executor.4:23482 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.4  D27208 23482   7375 0x80004004
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_timeout+0x1d8/0x250 kernel/time/timer.c:1873
 __down_common kernel/locking/semaphore.c:220 [inline]
 __down+0x183/0x2a0 kernel/locking/semaphore.c:237
 down+0x57/0x80 kernel/locking/semaphore.c:61
 console_lock+0x25/0x80 kernel/printk/printk.c:2309
 con_flush_chars drivers/tty/vt/vt.c:3236 [inline]
 con_flush_chars drivers/tty/vt/vt.c:3228 [inline]
 con_write+0x58/0xb0 drivers/tty/vt/vt.c:3160
 do_output_char+0x5de/0x850 drivers/tty/n_tty.c:447
 process_output drivers/tty/n_tty.c:514 [inline]
 n_tty_write+0x481/0xf80 drivers/tty/n_tty.c:2345
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x4d9/0x870 drivers/tty/tty_io.c:1046
 __kernel_write+0x199/0x500 fs/read_write.c:528
 write_pipe_buf+0x153/0x1f0 fs/splice.c:799
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x3dc/0x830 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 default_file_splice_write fs/splice.c:811 [inline]
 do_splice_from fs/splice.c:847 [inline]
 direct_splice_actor+0x228/0x2f0 fs/splice.c:1016
 splice_direct_to_actor+0x38c/0x980 fs/splice.c:971
 do_splice_direct+0x1b3/0x280 fs/splice.c:1059
 do_sendfile+0x559/0xc30 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1601 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1587
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cba9
Code: Bad RIP value.
RSP: 002b:00007f25202fcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004fe820 RCX: 000000000045cba9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0800000080004105 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000926 R14: 00000000004cbfac R15: 00007f25202fd6d4
INFO: task syz-executor.3:23526 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.3  D28752 23526   7160 0x00004004
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_sys_openat fs/open.c:1209 [inline]
 __se_sys_openat fs/open.c:1204 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1204
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cba9
Code: Bad RIP value.
RSP: 002b:00007f603de9ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00000000004f9760 RCX: 000000000045cba9
RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000007e3 R14: 00000000004cac7f R15: 00007f603de9b6d4

Showing all locks held in the system:
1 lock held by khungtaskd/1141:
 #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/6509:
 #0: ffff8880956c03f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826
4 locks held by syz-executor.4/23482:
 #0: ffff8880a663c098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267
 #1: ffff8880a663c130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:888 [inline]
 #1: ffff8880a663c130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: do_tty_write drivers/tty/tty_io.c:911 [inline]
 #1: ffff8880a663c130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write+0x280/0x870 drivers/tty/tty_io.c:1046
 #2: ffff8880a663c2e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_write+0x1bf/0xf80 drivers/tty/n_tty.c:2316
 #3: ffffc90000ff4378 (&ldata->output_lock){+.+.}-{3:3}, at: process_output drivers/tty/n_tty.c:511 [inline]
 #3: ffffc90000ff4378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x46c/0xf80 drivers/tty/n_tty.c:2345
2 locks held by syz-executor.3/23506:
1 lock held by syz-executor.3/23526:
 #0: ffff888218822078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline]
 #0: ffff888218822078 (&fb_info->lock){+.+.}-{3:3}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418

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

NMI backtrace for cpu 0
CPU: 0 PID: 1141 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 23506 Comm: syz-executor.3 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__sanitizer_cov_trace_pc+0x30/0x60 kernel/kcov.c:197
Code: ff 01 00 65 8b 05 b0 44 8e 7e a9 00 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74 35 8b 82 04 14 00 00 85 c0 74 2b 8b 82 e0 13 00 00 <83> f8 02 75 20 48 8b 8a e8 13 00 00 8b 92 e4 13 00 00 48 8b 01 48
RSP: 0018:ffffc900196775a8 EFLAGS: 00000246
RAX: 0000000000000002 RBX: 0000000000000050 RCX: ffffffff83c66774
RDX: ffff888018588340 RSI: ffffffff83c66760 RDI: 0000000000000004
RBP: 0000000000000019 R08: 0000000000000001 R09: ffff8880a366721f
R10: 0000000000000050 R11: 0000000000000000 R12: ffff8880000a0019
R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000f1bd4177
FS:  00007f603debc700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c000009c80 CR3: 000000004cac0000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 writeb arch/x86/include/asm/io.h:65 [inline]
 vga16fb_fillrect+0x9c0/0x193b drivers/video/fbdev/vga16fb.c:923
 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_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cba9
Code: Bad RIP value.
RSP: 002b:00007f603debbc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e5e20 RCX: 000000000045cba9
RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002fe R14: 00000000004c5931 R15: 00007f603debc6d4

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/07/15 06:45 upstream e9919e11e219 609fb517 .config console log report ci-upstream-kasan-gce
2020/06/18 22:13 upstream 7ae77150d94d d45a4d69 .config console log report ci-upstream-kasan-gce-selinux-root
2020/05/28 11:06 upstream b0c3ba31be3e 142a0957 .config console log report ci-upstream-kasan-gce-386
* Struck through repros no longer work on HEAD.