INFO: task syz.0.936:8825 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.936       state:D stack:27896 pid:8825  ppid:5773   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 nfsd_shutdown_threads+0x53/0x1a0 fs/nfsd/nfssvc.c:638
 nfsd_umount+0x42/0xc0 fs/nfsd/nfsctl.c:1464
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x3d7/0x460 fs/namespace.c:1259
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:294 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:305
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f291ef9e1d9
RSP: 002b:00007f291ff5a028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: fffffffffffffffe RBX: 00007f291f225fa0 RCX: 00007f291ef9e1d9
RDX: 00002000000069c0 RSI: 0000200000006980 RDI: 0000000000000000
RBP: 00007f291f035888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f291f226038 R14: 00007f291f225fa0 R15: 00007ffc7af8d0d8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/28:
 #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6669
2 locks held by udevd/5141:
2 locks held by getty/5523:
 #0: ffff888032b9a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217
3 locks held by syz.2.371/7067:
 #0: ffff88802ff6cd48 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040
 #1: 
ffff8881407e6418
 (
sb_writers#20){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580
 #2: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: write_ports+0xb7/0xfa0 fs/nfsd/nfsctl.c:843
2 locks held by syz.0.936/8825:
 #0: ffff8880765960e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880765960e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880765960e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_shutdown_threads+0x53/0x1a0 fs/nfsd/nfssvc.c:638
6 locks held by syz.8.1480/10431:
 #0: ffff88802fcf60e0 (&type->s_umount_key#62/1){+.+.}-{3:3}, at: alloc_super+0x1fb/0x910 fs/super.c:352
 #1: ffff88802fcf6608 (sb_internal#4){.+.+}-{0:0}, at: btrfs_delete_free_space_tree+0xde/0x670 fs/btrfs/free-space-tree.c:1277
 #2: ffff88807b146458 (btrfs_trans_completed){++++}-{0:0}, at: btrfs_commit_transaction+0x199/0x3500 fs/btrfs/transaction.c:2190
 #3: ffff88807b145f98 (&fs_info->unused_bg_unpin_mutex){+.+.}-{3:3}, at: btrfs_finish_extent_commit+0x18a/0x650 fs/btrfs/extent-tree.c:2832
 #4: ffff8880b8c28a00 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #4: ffff8880b8c28a00 (psi_seq){-.-.}-{0:0}, at: __schedule+0x21d3/0x4660 kernel/sched/core.c:6696
 #5: ffff8880b8c28a00 (psi_seq){-.-.}-{0:0}, at: psi_enqueue kernel/sched/stats.h:143 [inline]
 #5: ffff8880b8c28a00 (psi_seq){-.-.}-{0:0}, at: enqueue_task+0x23b/0x280 kernel/sched/core.c:2098

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a6/0x3e0 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+0xf59/0xfa0 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:
nf_nat: Already setup manip DST for ct ffff888025b3e900 (status bits 0x188)
nf_nat: Already setup manip SRC for ct ffff888025b3e900 (status bits 0x188)
nf_nat: Already setup manip SRC for ct ffff888025b3e900 (status bits 0x188)
nf_nat: Already setup manip DST for ct ffff888025b3e900 (status bits 0x188)
nf_nat: Already setup manip SRC for ct ffff888025b3e900 (status bits 0x188)
NMI backtrace for cpu 0
CPU: 0 PID: 5130 Comm: klogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:PagePoisoned include/linux/page-flags.h:297 [inline]
RIP: 0010:PageHead include/linux/page-flags.h:803 [inline]
RIP: 0010:__free_pages+0x28/0x210 mm/page_alloc.c:4584
Code: 00 00 f3 0f 1e fa 55 41 57 41 56 41 54 53 41 89 f6 48 89 fb 49 bc 00 00 00 00 00 fc ff df 49 89 ff 49 c1 ef 03 43 80 3c 27 00 <74> 08 48 89 df e8 6e c1 0b 00 48 8b 03 48 83 f8 ff 0f 84 4a 01 00
RSP: 0018:ffffc900032775d8 EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffea000146e5c0 RCX: dffffc0000000007
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: ffffea000146e5c0
RBP: ffff88801c241300 R08: ffffffff91ff152f R09: 1ffffffff23fe2a5
R10: dffffc0000000000 R11: fffffbfff23fe2a6 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffd400028dcb8
FS:  00007fb388cdfc80(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c4272de CR3: 0000000031beb000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 kmem_cache_alloc_node+0x1af/0x310 mm/slub.c:3540
 __alloc_skb+0x103/0x2c0 net/core/skbuff.c:643
 alloc_skb include/linux/skbuff.h:1316 [inline]
 alloc_skb_with_frags+0xcd/0x7a0 net/core/skbuff.c:6365
 sock_alloc_send_pskb+0x883/0x9a0 net/core/sock.c:2829
 unix_dgram_sendmsg+0x5a9/0x16e0 net/unix/af_unix.c:2013
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb388e2f407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffcd4de9f30 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fb388cdfc80 RCX: 00007fb388e2f407
RDX: 000000000000004b RSI: 00007ffcd4dea070 RDI: 0000000000000003
RBP: 00007ffcd4dea4a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000202 R12: 00007ffcd4dea4b8
R13: 00007ffcd4dea070 R14: 0000000000000030 R15: 00007ffcd4dea070
 </TASK>