syzbot


INFO: task hung in p9_fd_close (3)

Status: upstream: reported C repro on 2025/10/13 22:08
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+ed53e35a1e9dde289579@syzkaller.appspotmail.com
First crash: 20d, last: 13h21m
Cause bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] INFO: task hung in p9_fd_close (3) 0 (1) 2025/10/13 22:08
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in p9_fd_close v9fs 1 C error error 484 1091d 2255d 22/29 fixed on 2023/02/24 13:50
android-6-12 INFO: task hung in p9_fd_close origin:upstream 1 C 1 26d 41d 0/1 premoderation: reported C repro on 2025/09/22 01:10
linux-4.14 INFO: task hung in p9_fd_close 1 C inconclusive 78 1076d 2274d 0/1 upstream: reported C repro on 2019/08/11 15:06
upstream INFO: task hung in p9_fd_close (2) kernel 1 1 149d 149d 0/29 auto-obsoleted due to no activity on 2025/09/03 21:17
linux-5.15 INFO: task hung in p9_fd_close origin:lts-only 1 C error 2 39d 143d 0/3 upstream: reported C repro on 2025/06/11 07:14
linux-4.19 INFO: task hung in p9_fd_close 1 C error 219 976d 2266d 0/1 upstream: reported C repro on 2019/08/19 15:52
upstream INFO: task can't die in p9_fd_close 1 C done 58 1287d 1893d 0/29 closed as dup on 2022/08/26 12:44

Sample crash report:
INFO: task syz.0.18:6001 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.18        state:D stack:27464 pid:6001  tgid:6000  ppid:5950   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5254 [inline]
 __schedule+0x17c4/0x4d60 kernel/sched/core.c:6862
 __schedule_loop kernel/sched/core.c:6944 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6959
 schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:153
 __flush_work+0x9b9/0xbc0 kernel/workqueue.c:4277
 __cancel_work_sync+0xbe/0x110 kernel/workqueue.c:4397
 p9_conn_destroy net/9p/trans_fd.c:909 [inline]
 p9_fd_close+0x251/0x430 net/9p/trans_fd.c:944
 p9_client_create+0xd1c/0x10b0 net/9p/client.c:1060
 v9fs_session_init+0x1d7/0x19a0 fs/9p/v9fs.c:410
 v9fs_mount+0xc8/0xa50 fs/9p/vfs_super.c:122
 legacy_get_tree+0xfd/0x1a0 fs/fs_context.c:663
 vfs_get_tree+0x92/0x2b0 fs/super.c:1752
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3641 [inline]
 do_new_mount+0x302/0xa10 fs/namespace.c:3717
 do_mount fs/namespace.c:4040 [inline]
 __do_sys_mount fs/namespace.c:4228 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4205
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f333bb8efc9
RSP: 002b:00007f333c98b038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f333bde5fa0 RCX: 00007f333bb8efc9
RDX: 0000200000000280 RSI: 0000200000000180 RDI: 0000000000000000
RBP: 00007f333bc11f91 R08: 0000200000000580 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f333bde6038 R14: 00007f333bde5fa0 R15: 00007ffe591e10a8
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/1:0/24:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc900001e7ba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
1 lock held by khungtaskd/31:
 #0: ffffffff8df3d960 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3d960 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8df3d960 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/1:1/44:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc90000b47ba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
2 locks held by kworker/0:2/116:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc90002e07ba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
2 locks held by kworker/1:2/981:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc9000389fba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
2 locks held by getty/5583:
 #0: ffff8880341790a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
2 locks held by kworker/0:4/5903:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc90003edfba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
2 locks held by kworker/1:3/5958:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc90003837ba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
2 locks held by kworker/1:4/6028:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc90003c3fba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
3 locks held by kworker/1:5/6029:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc90003c5fba0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
 #2: ffff88807b82b240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1f7/0x3b0 drivers/net/netdevsim/fib.c:1490
2 locks held by kworker/0:5/6057:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc900039bfba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
2 locks held by kworker/1:6/6122:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc900036d7ba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243
2 locks held by kworker/1:8/6195:
 #0: ffff88813fe55948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x841/0x15d0 kernel/workqueue.c:3242
 #1: ffffc9000412fba0 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x868/0x15d0 kernel/workqueue.c:3243

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:337 [inline]
 watchdog+0xfa9/0xff0 kernel/hung_task.c:500
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 3556 Comm: kworker/u8:7 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:check_preemption_disabled+0x5/0x120 lib/smp_processor_id.c:13
Code: 48 c7 c6 a0 25 bf 8b eb 1c 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 <53> 48 83 ec 10 65 48 8b 05 de 84 1e 07 48 89 44 24 08 65 8b 05 e6
RSP: 0018:ffffc9000c256618 EFLAGS: 00000082
RAX: 0000000000000001 RBX: 0000000000000000 RCX: fc7371fc61727300
RDX: 0000000000000000 RSI: ffffffff8d9676f2 RDI: ffffffff8bbf25c0
RBP: ffffffff8173cf85 R08: 0000000000000000 R09: ffffffff8173cf85
R10: ffffc9000c2567f8 R11: ffffffff81acb160 R12: 0000000000000002
R13: ffffffff8df3d960 R14: 0000000000000000 R15: 0000000000000246
FS:  0000000000000000(0000) GS:ffff888125fe2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005567ee342660 CR3: 00000000308fa000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline]
 lock_acquire+0x130/0x360 kernel/locking/lockdep.c:5870
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:867 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1195 [inline]
 unwind_next_frame+0xc2/0x2390 arch/x86/kernel/unwind_orc.c:479
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:397 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __do_kmalloc_node mm/slub.c:5650 [inline]
 __kmalloc_noprof+0x41d/0x800 mm/slub.c:5662
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 ieee802_11_parse_elems_full+0x152/0x2ab0 net/mac80211/parse.c:1011
 ieee802_11_parse_elems_crc net/mac80211/ieee80211_i.h:2470 [inline]
 ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2477 [inline]
 ieee80211_inform_bss+0x10c/0x10a0 net/mac80211/scan.c:79
 rdev_inform_bss net/wireless/rdev-ops.h:418 [inline]
 cfg80211_inform_single_bss_data+0xd05/0x1ac0 net/wireless/scan.c:2385
 cfg80211_inform_bss_data+0x203/0x3b40 net/wireless/scan.c:3240
 cfg80211_inform_bss_frame_data+0x3d7/0x730 net/wireless/scan.c:3331
 ieee80211_bss_info_update+0x749/0x9e0 net/mac80211/scan.c:226
 ieee80211_rx_bss_info net/mac80211/ibss.c:1094 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1573 [inline]
 ieee80211_ibss_rx_queued_mgmt+0xa4e/0x2af0 net/mac80211/ibss.c:1600
 ieee80211_iface_process_skb net/mac80211/iface.c:1694 [inline]
 ieee80211_iface_work+0x85f/0x12d0 net/mac80211/iface.c:1748
 cfg80211_wiphy_work+0x2bb/0x470 net/wireless/core.c:438
 process_one_work+0x94a/0x15d0 kernel/workqueue.c:3267
 process_scheduled_works kernel/workqueue.c:3350 [inline]
 worker_thread+0x9b0/0xee0 kernel/workqueue.c:3431
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/01 17:02 linux-next 98bd8b16ae57 2c50b6a9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
2025/10/30 01:24 linux-next f9ba12abc528 fd2207e7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
2025/10/21 19:59 linux-next fe45352cd106 9832ed61 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
2025/10/21 06:29 linux-next 606da5bb1655 9832ed61 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
2025/10/19 08:36 linux-next 93f3bab4310d 1c8c8cd8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
2025/10/18 10:03 linux-next 93f3bab4310d 1c8c8cd8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
2025/10/17 05:28 linux-next 2433b8476165 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
2025/10/12 22:16 linux-next 2b763d465239 ff1712fe .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in p9_fd_close
* Struck through repros no longer work on HEAD.