syzkaller: INFO: task hung in `lock_sock_nested`

[cpaasch]

syzkaller-id: e4e5a43811c434e39a8ffd0c4913f213172c77c3

HEAD: 522c8fda3aa4

Trace:

INFO: task syz-executor.6:15320 blocked for more than 143 seconds.
      Not tainted 6.6.0-g522c8fda3aa4 #54
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.6  state:D stack:0     pid:15320 tgid:15246 ppid:794    flags:0x00004002
Call Trace:
 <TASK>
 __schedule+0x610/0x800 kernel/sched/core.c:5376
 __schedule_loop kernel/sched/core.c:6763 [inline]
 schedule+0x48/0x70 kernel/sched/core.c:6778
 __lock_sock net/core/sock.c:2944 [inline]
 lock_sock_nested+0xa1/0x110 net/core/sock.c:3524
 lock_sock include/net/sock.h:1720 [inline]
 mptcp_close+0x1d/0x100 net/mptcp/protocol.c:3085
 inet_release+0x88/0xa0 net/ipv4/af_inet.c:433
 sock_close+0x4b/0x100 net/socket.c:659
 __fput+0x1bc/0x530 fs/file_table.c:394
 task_work_run+0x104/0x140 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x3de/0xe80 kernel/exit.c:876
 do_group_exit+0x95/0xd0 kernel/exit.c:1026
 get_signal+0xccb/0xe10 kernel/signal.c:2900
 arch_do_signal_or_restart+0x33/0x410 arch/x86/kernel/signal.c:309
 exit_to_user_mode_loop+0x61/0xc0 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0x51/0x90 kernel/entry/common.c:204
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:285
 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242
 </TASK>

Kconfig: Kconfig_k7_clean.txt

No reproducer

[pabeni]

@cpaasch: could you please share the relevan syzkaller log up to ~150 seconds before the report?

are there any other reports - even non mptcp related - before this one? This sort of issues can be a side effect of something bad happening elsewhere - and lockdep should cover us quite nicely from real deadlock.

[cpaasch]

@pabeni - logs are not going that far back :-/

No other reports,... before that.

[matttbe]

@cpaasch should we close this bug report?

[cpaasch]

Sure.