INFO: task hung in p9_fd_close

Status: auto-obsoleted due to no activity on 2026/02/24 00:46
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+4478fa2290bed67597d3@syzkaller.appspotmail.com
First crash: 332d, last: 318d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/09/22 lts (merge base) d90ecb2b1308 C [report] INFO: task hung in p9_fd_close
2025/09/22 upstream (ToT) cec1e6e5d1ab C [report] INFO: task hung in p9_fd_close
▶ ▼ 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 syz, C error error 484 1382d 2546d 22/29 fixed on 2023/02/24 13:50
linux-4.14 INFO: task hung in p9_fd_close 1 syz, C inconclusive 78 1367d 2565d 0/1 upstream: reported C repro on 2019/08/11 15:06
upstream INFO: task hung in p9_fd_close (2) kernel 1 1 440d 440d 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 syz, C error 2 23d 435d 0/3 upstream: reported C repro on 2025/06/11 07:14
upstream INFO: task hung in p9_fd_close (3) prio:low kernel 1 syz, C error 222 56d 310d 0/29 upstream: reported C repro on 2025/10/13 22:08
linux-4.19 INFO: task hung in p9_fd_close 1 syz, C error 219 1267d 2557d 0/1 upstream: reported C repro on 2019/08/19 15:52
upstream INFO: task can't die in p9_fd_close 1 syz, C done 58 1578d 2185d 0/29 closed as dup on 2022/08/26 12:44
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2026/02/24 00:28 15m retest repro android16-6.12 no crash log
2025/12/15 21:48 3m retest repro android16-6.12 error
2025/10/06 08:13 16m retest repro android16-6.12 report log

Sample crash report:
INFO: task syz.2.158:809 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.158       state:D stack:0     pid:809   tgid:808   ppid:374    flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 schedule_timeout+0xb2/0x3a0 kernel/time/timer.c:2595
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x359/0x630 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 __flush_work+0x6d2/0xac0 kernel/workqueue.c:4233
 __cancel_work_sync kernel/workqueue.c:4354 [inline]
 cancel_work_sync+0xac/0xe0 kernel/workqueue.c:4391
 p9_conn_destroy net/9p/trans_fd.c:915 [inline]
 p9_fd_close+0x252/0x450 net/9p/trans_fd.c:950
 p9_client_create+0xc69/0x1190 net/9p/client.c:1060
 v9fs_session_init+0x1e1/0x1820 fs/9p/v9fs.c:410
 v9fs_mount+0xd7/0xa00 fs/9p/vfs_super.c:122
 legacy_get_tree+0x103/0x1b0 fs/fs_context.c:662
 vfs_get_tree+0x9e/0x290 fs/super.c:1817
 do_new_mount+0x251/0xb40 fs/namespace.c:3531
 path_mount+0x688/0x1050 fs/namespace.c:3858
 do_mount fs/namespace.c:3871 [inline]
 __do_sys_mount fs/namespace.c:4081 [inline]
 __se_sys_mount+0x2bd/0x480 fs/namespace.c:4058
 __x64_sys_mount+0xc3/0xf0 fs/namespace.c:4058
 x64_sys_call+0x2021/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x58/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f028d18ec29
RSP: 002b:00007f028cfff038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f028d3d5fa0 RCX: 00007f028d18ec29
RDX: 0000200000000400 RSI: 00002000000003c0 RDI: 0000000000000000
RBP: 00007f028d211e41 R08: 0000200000000440 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f028d3d6038 R14: 00007f028d3d5fa0 R15: 00007ffed0bb92c8
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 26040f0ed9382bf65720d717d6d6db2d10869199
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x10c/0x190 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2bf/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xd8f/0xed0 kernel/hung_task.c:423
 kthread+0x2c7/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 26040f0ed9382bf65720d717d6d6db2d10869199
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:pv_native_safe_halt+0x17/0x20 arch/x86/kernel/paravirt.c:106
Code: cc cc cc b8 95 cc 40 ae 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 93 a1 3a 00 f3 0f 1e fa 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff87207da0 EFLAGS: 000002c6
RAX: ffff8881f6e00000 RBX: ffffffff87215540 RCX: ffffffff858cb0ae
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000001b27ac
RBP: ffffffff87207da0 R08: ffff8881f6e39733 R09: 1ffff1103edc72e6
R10: dffffc0000000000 R11: ffffed103edc72e7 R12: 1ffffffff0e42aa8
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff87cb1ba8
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555743e14a8 CR3: 000000010bf22000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:112 [inline]
 default_idle+0x17/0x30 arch/x86/kernel/process.c:754
 arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:791
 default_idle_call+0x3f/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x1a0/0x470 kernel/sched/idle.c:326
 cpu_startup_entry+0x48/0x70 kernel/sched/idle.c:424
 rest_init+0x10b/0x130 init/main.c:748
 start_kernel+0x46a/0x4bb init/main.c:1135
 x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x6a/0x7b arch/x86/kernel/head64.c:488
 common_startup_64+0x13b/0x157
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/22 01:09 android16-6.12 8419b8c58fd1 67c37560 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in p9_fd_close
* Struck through repros no longer work on HEAD.