[v6.1] INFO: task hung in ppp_exit_net

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4078fa637fcd Linux 6.1.91
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1131903c980000
kernel config: https://syzkaller.appspot.com/x/.config?x=715ba80acfd3def4
dashboard link: https://syzkaller.appspot.com/bug?extid=1f82dbef70a30312f507
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/2443dfe91c62/disk-4078fa63.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/12dbc2af3348/vmlinux-4078fa63.xz
kernel image: https://storage.googleapis.com/syzbot-assets/da3589238e32/bzImage-4078fa63.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1f82db...@syzkaller.appspotmail.com

INFO: task kworker/u4:4:102 blocked for more than 143 seconds.
Not tainted 6.1.91-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:4 state:D stack:20416 pid:102 ppid:2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
ppp_exit_net+0xe0/0x3b0 drivers/net/ppp/ppp_generic.c:1129
ops_exit_list net/core/net_namespace.c:172 [inline]
cleanup_net+0x6ce/0xb60 net/core/net_namespace.c:604
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
INFO: task syz-executor.0:4823 blocked for more than 143 seconds.
Not tainted 6.1.91-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0 state:D stack:27320 pid:4823 ppid:3573 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558


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[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c61bd26ae81a Linux 5.15.160
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=134b0e0c980000
kernel config: https://syzkaller.appspot.com/x/.config?x=235f0e81ca937c17
dashboard link: https://syzkaller.appspot.com/bug?extid=25c310f6fa67cd864323

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/d61a97eef8b9/disk-c61bd26a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ab4908b4b59b/vmlinux-c61bd26a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d818fd46802b/bzImage-c61bd26a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+25c310...@syzkaller.appspotmail.com

INFO: task kworker/u4:1:144 blocked for more than 143 seconds.
Not tainted 5.15.160-syzkaller #0

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

task:kworker/u4:1 state:D stack:23224 pid: 144 ppid: 2 flags:0x00004000

Workqueue: netns cleanup_net
Call Trace:
<TASK>

context_switch kernel/sched/core.c:5030 [inline]
__schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
schedule+0x11b/0x1f0 kernel/sched/core.c:6459
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518
__mutex_lock_common+0xe34/0x25a0 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
ppp_exit_net+0xe0/0x3b0 drivers/net/ppp/ppp_generic.c:1128