syzbot


INFO: task hung in ret_from_fork

Status: auto-closed as invalid on 2019/02/22 10:29
Reported-by: syzbot+77cdbd57605c5e6b2e92@syzkaller.appspotmail.com
First crash: 1471d, last: 1460d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in ret_from_fork (2) 1 646d 646d 0/23 auto-closed as invalid on 2020/12/31 10:28

Sample crash report:
kworker/dying (50) used greatest stack depth: 11448 bytes left
INFO: task kthreadd:12261 blocked for more than 140 seconds.
      Not tainted 4.18.0-rc8+ #182
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kthreadd        D28056 12261      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2853 [inline]
 __schedule+0x87c/0x1ec0 kernel/sched/core.c:3501
 schedule+0xfb/0x450 kernel/sched/core.c:3545
 kthread+0x26a/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Showing all locks held in the system:
1 lock held by khungtaskd/772:
 #0: 00000000ab18c1fe (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4461
2 locks held by rs:main Q:Reg/4312:
 #0: 00000000f1364509 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766
 #1: 000000000bb09497 (sb_writers#6){.+.+}, at: file_start_write include/linux/fs.h:2738 [inline]
 #1: 000000000bb09497 (sb_writers#6){.+.+}, at: vfs_write+0x452/0x560 fs/read_write.c:548
1 lock held by rsyslogd/4314:
2 locks held by getty/4404:
 #0: 00000000af2f1fb8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000030c120d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4405:
 #0: 00000000fb07989e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000035899cd9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4406:
 #0: 00000000b695ba17 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000cfa9582e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4407:
 #0: 00000000a11992b9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000a0e524d4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4408:
 #0: 00000000ce4bec6a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000bc096b58 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4409:
 #0: 00000000e76d4a64 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000bfbd20a4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4410:
 #0: 0000000062e1df8e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000039721007 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
1 lock held by syz-executor2/12260:

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

NMI backtrace for cpu 0
CPU: 0 PID: 772 Comm: khungtaskd Not tainted 4.18.0-rc8+ #182
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+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline]
 watchdog+0x9c4/0xf80 kernel/hung_task.c:252
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54

Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2018/08/10 06:00 upstream 112cbae26d18 1fb62d58 .config log report
ci-upstream-linux-next-kasan-gce-root 2018/08/09 12:24 linux-next 1c2f2531cf8b 2eeda842 .config log report
ci-upstream-linux-next-kasan-gce-root 2018/08/06 06:16 linux-next 116b181bb646 1beb8136 .config log report
ci-upstream-linux-next-kasan-gce-root 2018/07/30 10:30 linux-next d1e0b8e0cb7a 1a381291 .config log report