linux-kernel - [syzbot] [kernel?] INFO: task hung in acct

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Message-ID: <68c9c3fc.050a0220.3c6139.0e67.GAE@google.com>
Date: Tue, 16 Sep 2025 13:09:32 -0700
From: syzbot <syzbot+514e8c53d21c55ef664b@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [kernel?] INFO: task hung in acct

Hello,

syzbot found the following issue on:

HEAD commit:    590b221ed425 Add linux-next specific files for 20250912
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17c22f62580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9134e501f17b95a4
dashboard link: https://syzkaller.appspot.com/bug?extid=514e8c53d21c55ef664b
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10222f62580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=109f4e42580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/872439e79d04/disk-590b221e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/09ebcfd707c1/vmlinux-590b221e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e3417bc549df/bzImage-590b221e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+514e8c53d21c55ef664b@...kaller.appspotmail.com

INFO: task syz.3.20:6136 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.20        state:D stack:25352 pid:6136  tgid:6136  ppid:6012   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7046 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7061
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7118
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
 __do_sys_acct kernel/acct.c:301 [inline]
 __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fee8a38eba9
RSP: 002b:00007ffd45f06b98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a3
RAX: ffffffffffffffda RBX: 00007fee8a5d5fa0 RCX: 00007fee8a38eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000180
RBP: 00007fee8a411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fee8a5d5fa0 R14: 00007fee8a5d5fa0 R15: 0000000000000001
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e53c820 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e53c820 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e53c820 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:4/65:
3 locks held by kworker/0:2/984:
 #0: ffff88801a871548 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
 #0: ffff88801a871548 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
 #1: ffff8880b8624008 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:933
 #2: ffff888078ee4fe0 (&r->consumer_lock#2){+.+.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #2: ffff888078ee4fe0 (&r->consumer_lock#2){+.+.}-{3:3}, at: ptr_ring_consume_bh include/linux/ptr_ring.h:365 [inline]
 #2: ffff888078ee4fe0 (&r->consumer_lock#2){+.+.}-{3:3}, at: wg_packet_decrypt_worker+0x87a/0xd10 drivers/net/wireguard/receive.c:499
2 locks held by getty/5627:
 #0: ffff88802fefb0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000331e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by syz.2.19/6135:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.3.20/6136:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.1.18/6137:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.0.17/6138:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
3 locks held by kworker/u8:8/6235:
1 lock held by syz.7.24/6244:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.4.21/6245:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.5.22/6247:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.6.23/6248:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.1.28/6342:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.0.27/6343:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.8.25/6344:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.9.26/6345:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.2.29/6423:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.3.30/6436:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.4.31/6446:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.5.32/6447:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.6.33/6503:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.7.34/6541:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.8.36/6547:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.1.35/6548:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.9.37/6577:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.0.38/6639:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.2.39/6645:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.3.40/6646:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.4.41/6673:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.5.42/6726:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.7.44/6755:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
1 lock held by syz.6.43/6756:
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __do_sys_acct kernel/acct.c:301 [inline]
 #0: ffffffff8e56f748 (acct_on_mutex){+.+.}-{4:4}, at: __se_sys_acct+0xb5/0x8d0 kernel/acct.c:293
3 locks held by syz-executor/6758:
 #0: ffffffff8f0c4220 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8f0c4220 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8f0c4220 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f955108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f955108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f955108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70 net/core/rtnetlink.c:4056
 #2: ffffffff8e5422b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
 #2: ffffffff8e5422b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730 kernel/rcu/tree_exp.h:957

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
 watchdog+0xf60/0xfa0 kernel/hung_task.c:495
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 50 Comm: kworker/u8:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:rcu_lock_release include/linux/rcupdate.h:341 [inline]
RIP: 0010:rcu_read_unlock include/linux/rcupdate.h:871 [inline]
RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
RIP: 0010:batadv_nc_worker+0x27d/0x610 net/batman-adv/network-coding.c:719
Code: 8b 5c 24 08 eb 24 e8 62 e5 66 f6 c6 05 1f fe 75 04 01 48 c7 c7 80 09 d9 8c be 66 03 00 00 48 c7 c2 20 0a d9 8c e8 b3 b0 44 f6 <48> c7 c7 20 c8 53 8e 4c 89 ee e8 94 96 44 f6 e8 0f 3a 4e f6 48 8b
RSP: 0018:ffffc90000ba7a00 EFLAGS: 00000293
RAX: ffffffff8b5925c1 RBX: ffff88807608ca80 RCX: ffff8880222d0000
RDX: 0000000000000000 RSI: ffffffff8c0503e0 RDI: ffffffff8c0503a0
RBP: fffffffffffffe38 R08: 0000000000000000 R09: ffffffff8b592482
R10: dffffc0000000000 R11: ffffffff8b5923b0 R12: dffffc0000000000
R13: ffffffff8b592482 R14: ffff888031244d80 R15: 00000000000000ef
FS:  0000000000000000(0000) GS:ffff8881258a7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3e77575e9c CR3: 0000000079c3e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
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