syzbot


INFO: task hung in nilfs_segctor_thread (2)

Status: upstream: reported on 2024/02/19 10:54
Subsystems: nilfs
[Documentation on labels]
Reported-by: syzbot+c8166c541d3971bf6c87@syzkaller.appspotmail.com
First crash: 66d, last: 57d
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly nilfs report (Mar 2024) 0 (1) 2024/03/05 11:10
[syzbot] [nilfs?] INFO: task hung in nilfs_segctor_thread (2) 1 (2) 2024/02/19 12:32
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in nilfs_segctor_thread nilfs2 C 41 431d 533d 0/1 upstream: reported C repro on 2022/11/05 03:06
upstream INFO: task hung in nilfs_segctor_thread nilfs C error 94 354d 528d 22/26 fixed on 2023/06/08 14:41
linux-5.15 INFO: task hung in nilfs_segctor_thread 3 365d 377d 0/3 auto-obsoleted due to no activity on 2023/08/20 05:29
linux-4.14 INFO: task hung in nilfs_segctor_thread nilfs2 C 1 430d 430d 0/1 upstream: reported C repro on 2023/02/16 07:03

Sample crash report:
INFO: task segctord:24786 blocked for more than 143 seconds.
      Not tainted 6.8.0-rc5-syzkaller-00121-g1c892cdd8fe0 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:segctord        state:D stack:28272 pid:24786 tgid:24786 ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5400 [inline]
 __schedule+0x17d1/0x49f0 kernel/sched/core.c:6727
 __schedule_loop kernel/sched/core.c:6802 [inline]
 schedule+0x149/0x260 kernel/sched/core.c:6817
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6874
 rwsem_down_write_slowpath+0xeea/0x13b0 kernel/locking/rwsem.c:1178
 __down_write_common+0x1ae/0x200 kernel/locking/rwsem.c:1306
 nilfs_transaction_lock+0x25c/0x4f0 fs/nilfs2/segment.c:357
 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2525 [inline]
 nilfs_segctor_thread+0x534/0x1150 fs/nilfs2/segment.c:2610
 kthread+0x2f1/0x390 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8e130c60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
 #0: ffffffff8e130c60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
 #0: ffffffff8e130c60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6614
2 locks held by getty/4822:
 #0: ffff88802ae530a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002efe2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b4/0x1e10 drivers/tty/n_tty.c:2201
4 locks held by syz-executor.3/5120:
 #0: ffff8880b953c958 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
 #1: ffff8880b9528988 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x441/0x770 kernel/sched/psi.c:988
 #2: ffff888078f473a0 (&mm->mmap_lock/1){+.+.}-{3:3}, at: mmap_write_lock_nested include/linux/mmap_lock.h:115 [inline]
 #2: ffff888078f473a0 (&mm->mmap_lock/1){+.+.}-{3:3}, at: dup_mmap kernel/fork.c:645 [inline]
 #2: ffff888078f473a0 (&mm->mmap_lock/1){+.+.}-{3:3}, at: dup_mm kernel/fork.c:1685 [inline]
 #2: ffff888078f473a0 (&mm->mmap_lock/1){+.+.}-{3:3}, at: copy_mm+0x3cb/0x21b0 kernel/fork.c:1734
 #3: ffffe8ffffd76bc8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x3a7/0x770 kernel/sched/psi.c:976
4 locks held by syz-executor.4/24778:
1 lock held by segctord/24786:
 #0: ffff88802355d2a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_lock+0x25c/0x4f0 fs/nilfs2/segment.c:357
1 lock held by syz-executor.4/28844:
2 locks held by syz-executor.5/28847:
1 lock held by syz-executor.3/28848:
 #0: ffff8880b953c958 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.8.0-rc5-syzkaller-00121-g1c892cdd8fe0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xfaf/0xff0 kernel/hung_task.c:379
 kthread+0x2f1/0x390 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 28860 Comm: syz-executor.3 Not tainted 6.8.0-rc5-syzkaller-00121-g1c892cdd8fe0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
RIP: 0010:__rcu_read_lock+0x0/0xb0 kernel/rcu/tree_plugin.h:401
Code: e8 65 e9 79 00 e9 02 fd ff ff e8 6b 2b eb 09 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 55 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 4c
RSP: 0018:ffffc90017e2f320 EFLAGS: 00000293
RAX: ffffffff82012f84 RBX: ffffea0000e1a680 RCX: ffff888029e19dc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffea0000e1a680
RBP: ffffea0000000000 R08: ffffffff82013abc R09: 1ffffffff1f0acdd
R10: dffffc0000000000 R11: fffffbfff1f0acde R12: ffff888030a87b98
R13: ffffc90017e2f860 R14: 0000000000000001 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555556cc2938 CR3: 00000000290de000 CR4: 0000000000350ef0
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 rcu_read_lock include/linux/rcupdate.h:748 [inline]
 page_ext_get+0x19/0x2a0 mm/page_ext.c:508
 page_table_check_clear+0x59/0x730 mm/page_table_check.c:72
 zap_pte_range mm/memory.c:1452 [inline]
 zap_pmd_range mm/memory.c:1597 [inline]
 zap_pud_range mm/memory.c:1626 [inline]
 zap_p4d_range mm/memory.c:1647 [inline]
 unmap_page_range+0x1f79/0x3600 mm/memory.c:1668
 unmap_vmas+0x3cc/0x5f0 mm/memory.c:1758
 exit_mmap+0x2c6/0xd40 mm/mmap.c:3279
 __mmput+0x115/0x3c0 kernel/fork.c:1343
 exit_mm+0x21f/0x310 kernel/exit.c:569
 do_exit+0x9af/0x2740 kernel/exit.c:858
 do_group_exit+0x206/0x2c0 kernel/exit.c:1020
 get_signal+0x176d/0x1850 kernel/signal.c:2893
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:105 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
 syscall_exit_to_user_mode+0xc8/0x370 kernel/entry/common.c:212
 do_syscall_64+0x108/0x240 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f6ba327dda9
Code: Unable to access opcode bytes at 0x7f6ba327dd7f.
RSP: 002b:00007f6ba3f64178 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f6ba33abf88 RCX: 00007f6ba327dda9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6ba33abf88
RBP: 00007f6ba33abf80 R08: 00007f6ba3f646c0 R09: 00007f6ba3f646c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6ba33abf8c
R13: 000000000000000b R14: 00007ffc9ce53c30 R15: 00007ffc9ce53d18
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/02/23 10:00 upstream 1c892cdd8fe0 8d446f15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in nilfs_segctor_thread
2024/02/15 00:10 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f735966ee23c 6a8ec742 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in nilfs_segctor_thread
* Struck through repros no longer work on HEAD.