[v6.6] INFO: task hung in iterate_supers

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16009d0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=739c128b5557abb9f816
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+739c12...@syzkaller.appspotmail.com

INFO: task syz.4.2517:15107 blocked for more than 144 seconds.
Not tainted 6.6.94-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.2517 state:D stack:28936 pid:15107 ppid:14447 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x14e2/0x4580 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
rwsem_down_read_slowpath+0x4f8/0x840 kernel/locking/rwsem.c:1086
__down_read_common kernel/locking/rwsem.c:1250 [inline]
__down_read kernel/locking/rwsem.c:1263 [inline]
down_read+0x98/0x2e0 kernel/locking/rwsem.c:1522
__super_lock fs/super.c:58 [inline]
super_lock+0x167/0x360 fs/super.c:117
super_lock_shared fs/super.c:146 [inline]
iterate_supers+0x80/0x170 fs/super.c:977
ksys_sync+0x95/0x150 fs/sync.c:102
__ia32_sys_sync+0xe/0x20 fs/sync.c:113
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8d7138e929
RSP: 002b:00007f8d721c6038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f8d715b5fa0 RCX: 00007f8d7138e929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f8d715b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8d715b5fa0 R15: 00007ffdcee38b48
</TASK>

Showing all locks held in the system:
5 locks held by kworker/u4:1/12:
1 lock held by khungtaskd/29:
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5531:
#0: ffff88823bde00a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000326b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
3 locks held by kworker/1:15/12241:
3 locks held by syz-executor/14118:
#0: ffff88805faf20e0 (&type->s_umount_key#95){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
#0: ffff88805faf20e0 (&type->s_umount_key#95){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
#0: ffff88805faf20e0 (&type->s_umount_key#95){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
#1: ffff8880b8e3c458 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
#2: ffff888018250018 (&pool->lock){-.-.}-{2:2}, at: __queue_work+0x69f/0x1020 kernel/workqueue.c:1764
1 lock held by syz-executor/14123:
#0: ffff88801efa20e0 (&type->s_umount_key#83){++++}-{3:3}, at: __super_lock fs/super.c:56 [inline]
#0: ffff88801efa20e0 (&type->s_umount_key#83){++++}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
#0: ffff88801efa20e0 (&type->s_umount_key#83){++++}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
1 lock held by syz.4.2517/15107:
#0: ffff88801efa20e0 (&type->s_umount_key#83){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88801efa20e0 (&type->s_umount_key#83){++++}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
4 locks held by syz-executor/15321:
1 lock held by syz.2.2798/16427:
3 locks held by dhcpcd-run-hook/16443:
#0: ffff8880b8e3c458 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
#1: ffff8880b8f288c8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x39c/0x6d0 kernel/sched/psi.c:998
#2: ffff88806682a5b8 (ptlock_ptr(ptdesc)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
#2: ffff88806682a5b8 (ptlock_ptr(ptdesc)#2){+.+.}-{2:2}, at: __pte_offset_map_lock+0x107/0x1e0 mm/pgtable-generic.c:375
1 lock held by syz.9.2804/16448:
#0: ffffffff8cd35600 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:4085
1 lock held by syz.3.2801/16460:
#0: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
#0: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x448/0x830 kernel/rcu/tree_exp.h:1004
4 locks held by rm/16461:

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x2f0 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+0xf41/0xf80 kernel/hung_task.c:379
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 12431 Comm: kworker/u4:17 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:check_kcov_mode kernel/kcov.c:193 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x36/0x60 kernel/kcov.c:216
Code: 20 24 7e 7e 65 8b 15 21 24 7e 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc
RSP: 0018:ffffc9000db5f560 EFLAGS: 00000246
RAX: ffffffff813ac8f9 RBX: ffffc9000db5f788 RCX: ffff88802bf0da00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffc9000db5f788
RBP: ffffc9000db5f698 R08: ffff88802bf0da00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc9000db5f648
R13: dffffc0000000000 R14: ffffc9000db5f788 R15: ffffffff8ecffd1a
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6221445000 CR3: 00000000274b2000 CR4: 00000000003526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__read_once_word_nocheck+0x9/0x10 include/asm-generic/rwonce.h:66
deref_stack_reg arch/x86/kernel/unwind_orc.c:406 [inline]
unwind_next_frame+0x15f9/0x2970 arch/x86/kernel/unwind_orc.c:585
arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1007 [inline]
__kmalloc_node_track_caller+0xb2/0x230 mm/slab_common.c:1027
kmalloc_reserve+0x117/0x260 net/core/skbuff.c:581
__alloc_skb+0x138/0x2c0 net/core/skbuff.c:650
alloc_skb include/linux/skbuff.h:1284 [inline]
nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
nsim_dev_trap_report_work+0x293/0xb00 drivers/net/netdevsim/dev.c:851
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


---
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If the report is already addressed, let syzbot know by replying with:
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If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 355bd0b51d2f Linux 6.6.104
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10122642580000
kernel config: https://syzkaller.appspot.com/x/.config?x=dac93b93d3de2741
dashboard link: https://syzkaller.appspot.com/bug?extid=739c128b5557abb9f816
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=13384b12580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14838d62580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ef00d28b2c5b/disk-355bd0b5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7627cd51eb0a/vmlinux-355bd0b5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3fdd0a51dd65/bzImage-355bd0b5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+739c12...@syzkaller.appspotmail.com

INFO: task syz.0.17:5967 blocked for more than 143 seconds.
Not tainted syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz.0.17 state:D stack:28400 pid:5967 ppid:5914 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832

rwsem_down_read_slowpath+0x4f8/0x840 kernel/locking/rwsem.c:1086
__down_read_common kernel/locking/rwsem.c:1250 [inline]
__down_read kernel/locking/rwsem.c:1263 [inline]
down_read+0x98/0x2e0 kernel/locking/rwsem.c:1522
__super_lock fs/super.c:58 [inline]
super_lock+0x167/0x360 fs/super.c:117
super_lock_shared fs/super.c:146 [inline]
iterate_supers+0x80/0x170 fs/super.c:977
ksys_sync+0x95/0x150 fs/sync.c:102
__ia32_sys_sync+0xe/0x20 fs/sync.c:113
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

RIP: 0033:0x7f62fdf8ebe9
RSP: 002b:00007f62fee24038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f62fe1c6090 RCX: 00007f62fdf8ebe9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000

RBP: 00007f62fe1c6090 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007f62fe1c6128 R14: 00007f62fe1c6090 R15: 00007ffde38a4368

</TASK>

Showing all locks held in the system:

1 lock held by khungtaskd/29:

#0: ffffffff8cd2fc20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2fc20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2fc20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5548:
#0: ffff88814c20c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz.0.17/5966:
#0: ffff88807ab7a0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.0.17/5967:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.1.18/5989:
#0: ffff8880710da0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.1.18/5991:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.2.19/6019:
#0: ffff8880799c00e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.2.19/6020:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.3.20/6042:
#0: ffff88802dda00e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.3.20/6043:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.4.21/6072:
#0: ffff88807814a0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.4.21/6073:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.5.22/6101:
#0: ffff88805ce800e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.5.22/6103:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.6.23/6139:
#0: ffff88805a7120e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.6.23/6140:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.7.24/6168:
#0: ffff88805b7100e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.7.24/6170:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.8.25/6199:
#0: ffff88805f56c0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.8.25/6200:
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025

Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x2f0 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+0xf41/0xf80 kernel/hung_task.c:379
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>

Sending NMI from CPU 1 to CPUs 0:

NMI backtrace for cpu 0

CPU: 0 PID: 1081 Comm: kworker/u4:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:separate_irq_context kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_acquire+0xe6a/0x7c80 kernel/locking/lockdep.c:5121
Code: 00 49 b8 00 00 00 00 00 fc ff df 4d 89 3e 48 8b 44 24 78 42 0f b6 04 00 84 c0 0f 85 60 5c 00 00 48 8b 44 24 40 8b 18 48 85 db <4c> 8b b4 24 a8 00 00 00 74 5a 83 fb 31 0f 83 50 5d 00 00 48 8d 04
RSP: 0018:ffffc9000474f7c0 EFLAGS: 00000002
RAX: ffff88802337c6d8 RBX: 0000000000000002 RCX: ffffffff81671330
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90da5500
RBP: ffffc9000474fa08 R08: dffffc0000000000 R09: 1ffffffff21b4aa0
R10: dffffc0000000000 R11: fffffbfff21b4aa1 R12: 0000000000000000
R13: ffff88802337bc00 R14: ffff88802337c730 R15: d7c71210ce46acba
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007ffd42a2e000 CR3: 000000003027e000 CR4: 00000000003506f0
Call Trace:
<TASK>
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
rcu_read_lock include/linux/rcupdate.h:786 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
batadv_nc_worker+0xef/0x610 net/batman-adv/network-coding.c:719

process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


---

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

syzbot suspects this issue could be fixed by backporting the following commit:

commit e8fe3f07a357c39d429e02ca34f740692d88967a
git tree: upstream
Author: Oleg Nesterov <ol...@redhat.com>
Date: Tue Aug 19 16:10:13 2025 +0000

9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16baf658580000

kernel config: https://syzkaller.appspot.com/x/.config?x=dac93b93d3de2741
dashboard link: https://syzkaller.appspot.com/bug?extid=739c128b5557abb9f816

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13384b12580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14838d62580000

Please keep in mind that other backports might be required as well.

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

For archival purposes, forwarding an incoming command email to
syzkaller...@googlegroups.com.

***

Subject: INFO: task hung in iterate_supers
Author: hellou...@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
5fa4793a2d2d70ad08b85387b41020f1fcc2d19e