Message-ID: <000000000000bf9aea061d9e8b1b@google.com>
Date: Fri, 19 Jul 2024 12:17:26 -0700
From: syzbot <syzbot+377059e0af6136c7d5c4@...kaller.appspotmail.com>
To: konishi.ryusuke@...il.com, linux-kernel@...r.kernel.org, 
	linux-nilfs@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [nilfs?] INFO: task hung in nilfs_segctor_thread (3)

Hello,

syzbot found the following issue on:

HEAD commit:    0434dbe32053 Merge tag 'linux_kselftest-next-6.11-rc1' of ..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d9612d980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4b8bd5292e033239
dashboard link: https://syzkaller.appspot.com/bug?extid=377059e0af6136c7d5c4
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3766752b5090/disk-0434dbe3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e3608abc3f91/vmlinux-0434dbe3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c133560ad498/bzImage-0434dbe3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+377059e0af6136c7d5c4@...kaller.appspotmail.com

INFO: task segctord:12059 blocked for more than 143 seconds.
      Not tainted 6.10.0-syzkaller-02711-g0434dbe32053 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:segctord        state:D stack:28272 pid:12059 tgid:12059 ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0x17ae/0x4a10 kernel/sched/core.c:6529
 __schedule_loop kernel/sched/core.c:6606 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6621
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6678
 rwsem_down_write_slowpath+0xeeb/0x13b0 kernel/locking/rwsem.c:1178
 __down_write_common kernel/locking/rwsem.c:1306 [inline]
 __down_write kernel/locking/rwsem.c:1315 [inline]
 down_write+0x1d7/0x220 kernel/locking/rwsem.c:1580
 nilfs_transaction_lock+0x25d/0x4f0 fs/nilfs2/segment.c:357
 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2515 [inline]
 nilfs_segctor_thread+0x551/0x11b0 fs/nilfs2/segment.c:2601
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e335fe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:327 [inline]
 #0: ffffffff8e335fe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:839 [inline]
 #0: ffffffff8e335fe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6613
2 locks held by kworker/u8:5/1034:
4 locks held by kworker/u8:7/1060:
 #0: ffff888015ed3148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3206 [inline]
 #0: ffff888015ed3148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x90a/0x1830 kernel/workqueue.c:3312
 #1: ffffc90004217d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3207 [inline]
 #1: ffffc90004217d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x945/0x1830 kernel/workqueue.c:3312
 #2: ffffffff8f5cfc90 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x16a/0xcc0 net/core/net_namespace.c:594
 #3: ffff8880b943e718 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:560
2 locks held by getty/4838:
 #0: ffff88802f2b10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900031332f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b5/0x1e10 drivers/tty/n_tty.c:2211
3 locks held by kworker/0:8/5199:
 #0: ffff888015080948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3206 [inline]
 #0: ffff888015080948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x90a/0x1830 kernel/workqueue.c:3312
 #1: ffffc90004467d00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3207 [inline]
 #1: ffffc90004467d00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x945/0x1830 kernel/workqueue.c:3312
 #2: ffff8880781c2240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x2d1/0x4130 drivers/net/netdevsim/fib.c:1489
2 locks held by syz.4.647/12057:
1 lock held by segctord/12059:
 #0: ffff88806aa062a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_lock+0x25d/0x4f0 fs/nilfs2/segment.c:357
1 lock held by syz-executor/14558:
 #0: ffffffff8e33b3b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:296 [inline]
 #0: ffffffff8e33b3b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x381/0x830 kernel/rcu/tree_exp.h:958
1 lock held by syz.3.965/14640:
 #0: ffffffff8e33b3b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:328 [inline]
 #0: ffffffff8e33b3b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x451/0x830 kernel/rcu/tree_exp.h:958
5 locks held by dhcpcd-run-hook/14674:

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

NMI backtrace for cpu 0
CPU: 0 PID: 30 Comm: khungtaskd Not tainted 6.10.0-syzkaller-02711-g0434dbe32053 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 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:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xfde/0x1020 kernel/hung_task.c:379
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 14367 Comm: syz-executor Not tainted 6.10.0-syzkaller-02711-g0434dbe32053 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:unwind_next_frame+0x1bad/0x2a00 arch/x86/kernel/unwind_orc.c:682
Code: 85 db 0f 84 74 04 00 00 e8 80 30 55 00 43 0f b6 04 2f 84 c0 0f 85 8e 05 00 00 c7 45 00 00 00 00 00 31 c0 48 81 c4 a0 00 00 00 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 4f 30 55 00 43 80
RSP: 0018:ffffc90004bff4a0 EFLAGS: 00000286
RAX: ffffffff81412e01 RBX: 0000000080000000 RCX: ffff88802a13bc00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc90004bff540 R08: ffffffff81412e85 R09: ffffffff8141297f
R10: 0000000000000003 R11: ffff88802a13bc00 R12: ffffc90004bff540
R13: dffffc0000000000 R14: ffffc90004bf8000 R15: ffffc90004bff548
FS:  0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000559dc10c4a18 CR3: 0000000063d66000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 __unwind_start+0x641/0x7c0 arch/x86/kernel/unwind_orc.c:760
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0x103/0x1b0 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
 save_stack+0xfb/0x1f0 mm/page_owner.c:156
 __reset_page_owner+0x75/0x3f0 mm/page_owner.c:297
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1093 [inline]
 free_unref_page+0xd19/0xea0 mm/page_alloc.c:2588
 vfree+0x186/0x2e0 mm/vmalloc.c:3363
 kcov_put kernel/kcov.c:429 [inline]
 kcov_close+0x2b/0x50 kernel/kcov.c:525
 __fput+0x24a/0x8a0 fs/file_table.c:422
 task_work_run+0x24f/0x310 kernel/task_work.c:222
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xa2f/0x27f0 kernel/exit.c:877
 do_group_exit+0x207/0x2c0 kernel/exit.c:1026
 get_signal+0x16a1/0x1740 kernel/signal.c:2917
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4aac5777ac
Code: Unable to access opcode bytes at 0x7f4aac577782.
RSP: 002b:00007ffdc6a34ef0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: 0000000000000028 RBX: 00007f4aad234620 RCX: 00007f4aac5777ac
RDX: 0000000000000028 RSI: 00007f4aad234670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffdc6a34f44 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f4aad234670 R15: 0000000000000000
 </TASK>


---
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