syzbot

INFO: task syz-executor:3641 blocked for more than 143 seconds.
      Not tainted 6.1.108-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:20536 pid:3641  ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 schedule_timeout+0xac/0x300 kernel/time/timer.c:1941
 do_wait_for_common kernel/sched/completion.c:85 [inline]
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x350/0x610 kernel/sched/completion.c:138
 kthread_stop+0x1ab/0x690 kernel/kthread.c:709
 ext4_stop_mmpd+0x43/0xb0 fs/ext4/mmp.c:261
 ext4_put_super+0xb49/0x10e0 fs/ext4/super.c:1293
 generic_shutdown_super+0x130/0x340 fs/super.c:501
 kill_block_super+0x7a/0xe0 fs/super.c:1470
 deactivate_locked_super+0xa0/0x110 fs/super.c:332
 cleanup_mnt+0x490/0x520 fs/namespace.c:1186
 task_work_run+0x246/0x300 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f00e217e227
RSP: 002b:00007ffc3c57cc18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f00e21eeee4 RCX: 00007f00e217e227
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc3c57ccd0
RBP: 00007ffc3c57ccd0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffc3c57dd50
R13: 00007f00e21eeee4 R14: 0000000000011106 R15: 00007ffc3c57dd90
 </TASK>
INFO: task kmmpd-loop2:3875 blocked for more than 144 seconds.
      Not tainted 6.1.108-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kmmpd-loop2     state:D stack:27424 pid:3875  ppid:2      flags:0x00024000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 percpu_rwsem_wait+0x3b9/0x450 kernel/locking/percpu-rwsem.c:162
 __percpu_down_read+0xe6/0x130 kernel/locking/percpu-rwsem.c:177
 percpu_down_read include/linux/percpu-rwsem.h:65 [inline]
 __sb_start_write include/linux/fs.h:1891 [inline]
 sb_start_write include/linux/fs.h:1966 [inline]
 write_mmp_block+0x2ee/0x390 fs/ext4/mmp.c:66
 kmmpd+0x263/0xa70 fs/ext4/mmp.c:246
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d32b190 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d32b990 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8d32afc0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d32afc0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d32afc0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6494
1 lock held by dhcpcd/3304:
 #0: ffff8880b8e3a9d8 (&rq->__lock){-.-.}-{2:2}, at: __unix_dgram_recvmsg+0x24d/0x1260 net/unix/af_unix.c:2431
2 locks held by getty/3394:
 #0: ffff88814b013098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc900031332f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a7/0x1db0 drivers/tty/n_tty.c:2198
1 lock held by syz-executor/3641:
 #0: ffff88805797c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:362
1 lock held by syz-executor/3643:
 #0: ffff8880294a80e0 (&type->s_umount_key#31){++++}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:362
1 lock held by syz-executor/3645:
 #0: ffff8880563cc0e0 (&type->s_umount_key#31){++++}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:362
1 lock held by kmmpd-loop2/3875:
 #0: ffff88805797c460 (sb_writers#4){++++}-{0:0}, at: kmmpd+0x263/0xa70 fs/ext4/mmp.c:246
1 lock held by kmmpd-loop3/3990:
 #0: ffff8880294a8460 (sb_writers#4){++++}-{0:0}, at: kmmpd+0x263/0xa70 fs/ext4/mmp.c:246
1 lock held by kmmpd-loop4/4023:
 #0: ffff8880563cc460 (sb_writers#4){++++}-{0:0}, at: kmmpd+0x263/0xa70 fs/ext4/mmp.c:246
2 locks held by syz.0.92/4078:
 #0: ffff888078a4c460 (sb_writers#3){.+.+}-{0:0}, at: do_sendfile+0x5f4/0xff0 fs/read_write.c:1254
 #1: ffff88805797c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xac/0x1e0 fs/super.c:755

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 6.1.108-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1ae/0x3f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf88/0xfd0 kernel/hung_task.c:377
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3080 Comm: klogd Not tainted 6.1.108-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:check_preemption_disabled+0x6/0x110 lib/smp_processor_id.c:13
Code: de e8 0e f1 bd f9 e9 6d ff ff ff cc cc cc cc cc cc cc cc cc 48 c7 c7 60 69 5d 8b 48 c7 c6 a0 69 5d 8b eb 00 41 57 41 56 41 54 <53> 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65 8b 1d
RSP: 0018:ffffc9000314f6f0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff816b3c52
RDX: dffffc0000000000 RSI: ffffffff8b0c13e0 RDI: ffffffff8b5d69c0
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff223b645
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000046
R13: ffff88807ced9dc0 R14: 00000000ffffffff R15: ffff8880b8e43ef0
FS:  00007f38675a0380(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056150a2bfa18 CR3: 000000007e648000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
 lock_is_held_type+0xfd/0x180 kernel/locking/lockdep.c:5706
 lock_is_held include/linux/lockdep.h:283 [inline]
 get_freelist mm/slub.c:3013 [inline]
 ___slab_alloc+0x2a6/0x1270 mm/slub.c:3108
 __slab_alloc mm/slub.c:3279 [inline]
 slab_alloc_node mm/slub.c:3364 [inline]
 kmem_cache_alloc_node+0x1cf/0x310 mm/slub.c:3443
 __alloc_skb+0xde/0x670 net/core/skbuff.c:505
 alloc_skb include/linux/skbuff.h:1271 [inline]
 alloc_skb_with_frags+0xa4/0x740 net/core/skbuff.c:6162
 sock_alloc_send_pskb+0x915/0xa50 net/core/sock.c:2747
 unix_dgram_sendmsg+0x5b1/0x2050 net/unix/af_unix.c:1925
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 __sys_sendto+0x480/0x600 net/socket.c:2148
 __do_sys_sendto net/socket.c:2160 [inline]
 __se_sys_sendto net/socket.c:2156 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2156
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f38677029b5
Code: 8b 44 24 08 48 83 c4 28 48 98 c3 48 98 c3 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 26 45 31 c9 45 31 c0 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 7a 48 8b 15 44 c4 0c 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffd82f87418 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f38677029b5
RDX: 0000000000000047 RSI: 000055ec7ca65c10 RDI: 0000000000000003
RBP: 000055ec7ca5f910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000246 R12: 0000000000000013
R13: 00007f3867890212 R14: 00007ffd82f87518 R15: 0000000000000000
 </TASK>