INFO: task hung in nfsd_nl_unlock_filesystem_doit

Status: upstream: reported on 2026/08/28 07:35
Subsystems: nfs
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+0093d3ab8d8eb2fdde82@syzkaller.appspotmail.com
First crash: 60d, last: 1d06h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
d9b93f35 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: task hung in nfsd_nl_unlock_filesystem_doit 2026/07/15 00:06 2026/07/15 00:06 2026/07/15 00:56 2130f682
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [nfs?] INFO: task hung in nfsd_nl_unlock_filesystem_doit 0 (1) 2026/08/28 07:35

Sample crash report:
INFO: task syz.5.8421:23278 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.8421      state:D stack:26344 pid:23278 tgid:23276 ppid:14788  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x16d9/0x5700 kernel/sched/core.c:7276
 __schedule_loop kernel/sched/core.c:7353 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7660
 rt_mutex_slowlock_block+0x55e/0x690 kernel/locking/rtmutex.c:1670
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1787 [inline]
 rt_mutex_slowlock+0x2d4/0x780 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:562 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:580
 nfsd_nl_unlock_filesystem_doit+0x2af/0x410 fs/nfsd/nfsctl.c:2677
 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7f5/0x990 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0x565/0x870 net/socket.c:2713
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
 __sys_sendmsg net/socket.c:2799 [inline]
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __x64_sys_sendmsg+0x1b7/0x290 net/socket.c:2802
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f415084e159
RSP: 002b:00007f414eaa6028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f4150ad5fa0 RCX: 00007f415084e159
RDX: 0000000004000080 RSI: 0000200000000100 RDI: 0000000000000003
RBP: 00007f41508e503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4150ad6038 R14: 00007f4150ad5fa0 R15: 00007ffcdae1fbf8
 </TASK>

Showing all locks held in the system:
locks held by kworker/0:1/10: 3, last CPU#0:
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc900000f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc900000f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc900000f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc900000f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: gc_worker+0x274/0x18b0 net/netfilter/nf_conntrack_core.c:1532
locks held by pr/ttyS0/17: 3, last CPU#0:
 #0: ffffffff8e09d5f8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
 #0: ffffffff8e09d5f8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
 #0: ffffffff8e09d5f8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291
 #1: ffffffff99e9c1f8 (&port_lock_key){+.+.}-{3:3}, at: nbcon_emit_one kernel/printk/nbcon.c:1137 [inline]
 #1: ffffffff99e9c1f8 (&port_lock_key){+.+.}-{3:3}, at: nbcon_kthread_func+0x64c/0x880 kernel/printk/nbcon.c:1271
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
locks held by khungtaskd/38: 1, last CPU#1:
 #0: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by kworker/u8:23/1551: 2, on CPU#0:
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90007877c40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90007877c40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90007877c40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90007877c40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
locks held by klogd/4951: 1, last CPU#1:
 #0: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
 #0: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495
locks held by getty/5346: 2, on CPU#0:
 #0: ffff8880371460a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900044c32e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
locks held by syz-executor/5581: 4, last CPU#1:
 #0: ffff8880415e47b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
 #0: ffff8880415e47b0 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x1a4/0x9f0 mm/mmap.c:1299
 #1: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
 #2: ffff888041e814d8 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff888041e814d8 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:404
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
locks held by syz-executor/5883: 9, last CPU#1:
 #0: ffffffff8e29f030 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline]
 #0: ffffffff8e29f030 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x10f/0x480 kernel/fork.c:1595
 #1: ffff88813ff50430 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
 #1: ffff88813ff50430 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x18e/0x1d80 mm/mmap.c:1716
 #2: ffff88801fac3a30 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline]
 #2: ffff88801fac3a30 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x27d/0x1d80 mm/mmap.c:1723
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
 #4: ffff888068aa1b98 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #4: ffff888068aa1b98 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:404
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
 #6: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #6: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #6: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
 #7: ffff88803e04a358 (ptlock_ptr(ptdesc)#2/1){+.+.}-{3:3}, at: copy_pte_range mm/memory.c:1354 [inline]
 #7: ffff88803e04a358 (ptlock_ptr(ptdesc)#2/1){+.+.}-{3:3}, at: copy_pmd_range+0x569/0x58f0 mm/memory.c:1490
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock_nested+0x1e0/0x400 kernel/locking/spinlock_rt.c:65
locks held by syz.4.5841/17873: 2, on CPU#0:
 #0: ffffffff8f643ae0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8e4f7898 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x53b/0x1a90 fs/nfsd/nfsctl.c:2057
locks held by syz-executor/18278: 10, last CPU#1:
 #0: ffffffff8e29f030 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline]
 #0: ffffffff8e29f030 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x10f/0x480 kernel/fork.c:1595
 #1: ffff888011a2c7b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
 #1: ffff888011a2c7b0 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x18e/0x1d80 mm/mmap.c:1716
 #2: ffff88801fac11b0 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline]
 #2: ffff88801fac11b0 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x27d/0x1d80 mm/mmap.c:1723
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
 #4: ffff888068aa1118 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #4: ffff888068aa1118 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:404
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #5: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
 #6: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #6: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #6: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
 #7: ffff888061bc3b98 (ptlock_ptr(ptdesc)#2/1){+.+.}-{3:3}, at: copy_pte_range mm/memory.c:1354 [inline]
 #7: ffff888061bc3b98 (ptlock_ptr(ptdesc)#2/1){+.+.}-{3:3}, at: copy_pmd_range+0x569/0x58f0 mm/memory.c:1490
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #8: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock_nested+0x1e0/0x400 kernel/locking/spinlock_rt.c:65
 #9: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #9: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #9: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: page_table_check_set+0x127/0x530 mm/page_table_check.c:112
locks held by syz.5.8421/23278: 2, on CPU#1:
 #0: ffffffff8f643ae0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8e4f7898 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_unlock_filesystem_doit+0x2af/0x410 fs/nfsd/nfsctl.c:2677
locks held by syz.7.9139/24816: 3, on CPU#1:
 #0: ffffffff8f643ae0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffff888040bf4928 (nlk_cb_mutex-GENERIC){+.+.}-{4:4}, at: __netlink_dump_start+0xf4/0x7b0 net/netlink/af_netlink.c:2410
 #2: ffffffff8e4f7898 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_expkey_get_reqs_dumpit+0xfb/0xd60 fs/nfsd/export.c:347
locks held by syz.1.9834/26319: 2, on CPU#0:
 #0: ffffffff8f643ae0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8e4f7898 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_cache_flush_doit+0xb5/0x1b0 fs/nfsd/nfsctl.c:2319
locks held by syz.0.10386/27573: 5, last CPU#1:
 #0: ffff8880276bf518 (mapping.invalidate_lock){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1089 [inline]
 #0: ffff8880276bf518 (mapping.invalidate_lock){++++}-{4:4}, at: do_page_cache_ra mm/readahead.c:347 [inline]
 #0: ffff8880276bf518 (mapping.invalidate_lock){++++}-{4:4}, at: force_page_cache_ra+0x261/0x2e0 mm/readahead.c:378
 #1: ffff8880276bf480 (&xa->xa_lock#7){+.+.}-{3:3}, at: spin_lock_irq include/linux/spinlock_rt.h:96 [inline]
 #1: ffff8880276bf480 (&xa->xa_lock#7){+.+.}-{3:3}, at: __filemap_add_folio+0x9d8/0x1250 mm/filemap.c:875
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: lruvec_stat_mod_folio+0x6e/0x3e0 mm/memcontrol.c:1028
 #4: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #4: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #4: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: get_non_dying_memcg_start mm/memcontrol.c:862 [inline]
 #4: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: mod_memcg_lruvec_state+0xd5/0x270 mm/memcontrol.c:992
locks held by syz.9.10385/27572: 4, last CPU#1:
 #0: ffff88801fac1f30 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
 #0: ffff88801fac1f30 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x1a4/0x9f0 mm/mmap.c:1299
 #1: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
 #2: ffff888032728dd8 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff888032728dd8 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:404
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #3: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
locks held by syz.8.10387/27575: 3, last CPU#0:
 #0: ffff88801fac0430 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:544 [inline]
 #0: ffff88801fac0430 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x2d8/0x9f0 mm/mmap.c:1323
 #1: ffff88801ea8d568 (&anon_vma->rwsem){++++}-{4:4}, at: anon_vma_lock_write mm/internal.h:295 [inline]
 #1: ffff88801ea8d568 (&anon_vma->rwsem){++++}-{4:4}, at: unlink_anon_vmas+0x119/0x720 mm/rmap.c:493
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
 #2: ffffffff8e1c3b40 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123
 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66
 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x38b/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 17 Comm: pr/ttyS0 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409
Code: e8 8e 7f 65 fc 44 89 f9 d3 e3 49 83 ee 80 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 ef 65 d1 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc900001678b8 EFLAGS: 00000202
RAX: 1ffffffff33d3800 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff85610e30 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff99e9c220 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125bd1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc4ad9ab840 CR3: 000000006eb5c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:128 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
 wait_for_lsr+0x190/0x300 drivers/tty/serial/8250/8250_port.c:2013
 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3270 [inline]
 __serial8250_console_fifo_write+0xd0/0x3f0 drivers/tty/serial/8250/8250_port.c:3345
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline]
 __serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline]
 serial8250_console_write+0xac5/0x1230 drivers/tty/serial/8250/8250_port.c:3493
 nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1
 nbcon_emit_one kernel/printk/nbcon.c:1157 [inline]
 nbcon_kthread_func+0x679/0x880 kernel/printk/nbcon.c:1271
 kthread+0x38b/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (52):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/09 17:37 upstream 893e11787f78 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/03 21:16 upstream 940de590b839 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/26 18:05 upstream 45c13f3f9e3b a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/26 13:46 upstream 45c13f3f9e3b 6a91adb4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/25 09:51 upstream 66498c75b4f8 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/10 12:19 net 7f26a5e8040b 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/10 03:55 net a401a9d547c5 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/09 13:53 net ba4ba11ed6eb 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/09 09:43 net ba4ba11ed6eb 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/09 07:51 net ba4ba11ed6eb 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/09 06:49 net ba4ba11ed6eb 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/09/08 21:12 net e0554c6276da 243b72f1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/25 02:09 net 3e995a30b9e3 23caa175 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/18 05:43 net ad27ed7d2309 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/18 03:06 net ad27ed7d2309 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/17 23:37 net ad27ed7d2309 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/16 06:37 net 24ef02f934ee 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/13 18:45 net 9006c116dd11 a9ede23c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/11 22:01 net b37971686ec5 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/11 20:49 net b37971686ec5 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/11 15:54 net b37971686ec5 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/27 23:37 net 53658c6f3682 4cb2b096 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/25 05:43 net 78f75d632f74 05b26a28 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/22 15:13 net ba712ecfd942 b561ce9c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/30 00:03 net-next 1b78070aaef6 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/29 15:31 net-next 1b78070aaef6 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/29 14:09 net-next 1b78070aaef6 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 12:04 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 11:30 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 10:41 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 07:16 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 06:16 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 03:11 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 02:53 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/24 00:58 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/23 15:14 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/23 13:54 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/23 12:14 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/23 04:50 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/23 00:48 net-next 91ec20351349 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/17 09:56 net-next e6a5d573d24c 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/11 22:46 net-next b54074ffb813 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/11 20:19 net-next b54074ffb813 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/11 18:08 net-next b54074ffb813 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/24 13:27 net-next 89d8006259b8 544adce9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/22 00:55 net-next abc435224e87 7c5de9c3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/08/30 00:57 linux-next e30626823a40 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/25 07:47 linux-next cc2b5f627e8c 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/13 22:44 linux-next 49362394dad7 2130f682 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
2026/07/13 06:06 linux-next bee763d5f341 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in nfsd_nl_unlock_filesystem_doit
* Struck through repros no longer work on HEAD.