INFO: task hung in cgroup1_get_tree

Status: upstream: reported on 2026/06/26 05:10
Subsystems: cgroups
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+4e415f7013e8d1af362b@syzkaller.appspotmail.com
First crash: 143d, last: 1d10h
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ID Workflow Result Correct Bug Created Started Finished Revision
0dc41483 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: task hung in cgroup1_get_tree 2026/06/02 07:01 2026/06/02 07:01 2026/06/02 07:10 1095583b
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[syzbot] [cgroups?] INFO: task hung in cgroup1_get_tree 0 (1) 2026/06/26 05:10

Sample crash report:
INFO: task syz.2.7055:28147 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.2.7055      state:D stack:26080 pid:28147 tgid:28146 ppid:25454  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5533 [inline]
 __schedule+0x17db/0x58f0 kernel/sched/core.c:7284
 __schedule_loop kernel/sched/core.c:7361 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7376
 cgroup_lock_and_drain_offline+0x51a/0x650 kernel/cgroup/cgroup.c:3350
 cgroup1_get_tree+0x9d/0x890 kernel/cgroup/cgroup-v1.c:1265
 vfs_get_tree+0x92/0x2a0 fs/super.c:1932
 vfs_cmd_create+0xa2/0x200 fs/fsopen.c:231
 __do_sys_fsconfig fs/fsopen.c:463 [inline]
 __se_sys_fsconfig+0x6b9/0x810 fs/fsopen.c:350
 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: 0033:0x7f139b79e1d9
RSP: 002b:00007f139c726028 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 00007f139ba25fa0 RCX: 00007f139b79e1d9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f139b835888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f139ba26038 R14: 00007f139ba25fa0 R15: 00007f139bb4fa48
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/31: 1, last CPU#1:
 #0: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by getty/5373: 2, on CPU#0:
 #0: ffff88803387d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032432e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by syz.2.7055/28147: 1, on CPU#1:
 #0: ffff88809f3f9468 (&fc->uapi_mutex){+.+.}-{4:4}, at: __do_sys_fsconfig fs/fsopen.c:461 [inline]
 #0: ffff88809f3f9468 (&fc->uapi_mutex){+.+.}-{4:4}, at: __se_sys_fsconfig+0x68d/0x810 fs/fsopen.c:350

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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/0x480 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: 0 Comm: swapper/0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64
Code: 4b 8b 02 e9 c3 08 03 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d e3 15 21 00 fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffffff8fa07ca0 EFLAGS: 00000242
RAX: 00000000014f2e6d RBX: ffffffff819bebe0 RCX: 8000000000000001
RDX: 0000000000000001 RSI: ffffffff8e46882c RDI: ffffffff8c6dd880
RBP: ffffffff8fa07d78 R08: ffff8880b8433a1b R09: 1ffff11017086743
R10: dffffc0000000000 R11: ffffed1017086744 R12: 0000000000000000
R13: 1ffffffff1f51e00 R14: 1ffffffff1f40f9c R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888123ac0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbc8127c5b1 CR3: 000000000fb48000 CR4: 00000000003526f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/kernel/process.c:767 [inline]
 default_idle+0x9/0x20 arch/x86/kernel/process.c:768
 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x2e0/0x540 kernel/sched/idle.c:355
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454
 rest_init+0x378/0x3a0 init/main.c:732
 start_kernel+0x392/0x3e0 init/main.c:1190
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x137/0x1b0 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x157
 </TASK>

Crashes (288):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/09 09:18 upstream 6c377d19d4a5 b2734a59 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/10/02 13:29 upstream ce1e0223d8ad 6d32eb1f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/10/01 01:18 upstream 551c722f4080 892a21ec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/09/29 09:02 upstream 72d3fcf802c4 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/09/26 16:34 upstream 6812ce4e4379 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/09/24 15:58 upstream 62f4c998b297 3c3cdf19 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/09/23 16:40 upstream fe2ec83746e5 abce1216 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/09/23 01:54 upstream c4e9f74da438 3e2106e5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/09/21 04:29 upstream 518e5b794c06 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/09/16 11:02 upstream 9b87fdc9af2f 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/09/15 20:33 upstream 587858367581 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/09/13 10:03 upstream cba2348ab114 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/09/12 23:06 upstream 5225b8eec4c9 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/09/10 20:26 upstream 50d05c7c76c9 1fe56c0a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/09/09 15:55 upstream 893e11787f78 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/09/06 19:09 upstream 1fc5a74b108f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/09/06 08:20 upstream 0d9ff90a5422 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/09/05 18:36 upstream 654ae5d73c05 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/09/04 23:46 upstream 986c24e0fe44 3f042c7b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/09/04 11:19 upstream 841e384b841a 801f0966 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/09/02 11:24 upstream 89a312991dc6 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/09/02 06:20 upstream 786262be6048 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/31 09:25 upstream a23cbb05744b 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/30 19:50 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/30 08:45 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/30 03:53 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/29 11:15 upstream cf72cbb39da8 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/28 12:17 upstream 1b78070aaef6 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/28 03:19 upstream 73e3f0710014 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/08/28 02:55 upstream 18fbf5151d2c e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/28 01:47 upstream 73e3f0710014 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/27 23:57 upstream 73e3f0710014 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/27 21:38 upstream 18fbf5151d2c e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/26 00:26 upstream 66498c75b4f8 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/08/22 00:50 upstream 818bebeb63dd 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in cgroup1_get_tree
2026/06/25 10:32 upstream ab9de95c9cf9 cfa969bf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/06/22 04:55 upstream 8cd8cf7a07e5 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/06/19 16:16 upstream 8c13415c8a43 d7ffd47b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/10/06 09:52 upstream 2c3418fffa9d f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: task hung in cgroup1_get_tree
2026/09/17 21:51 upstream 50d05c7c76c9 95928915 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: task hung in cgroup1_get_tree
2026/08/23 21:43 upstream 2709dd5ae32f 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: task hung in cgroup1_get_tree
2026/09/13 03:59 linux-next 9d80aa4617b3 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/31 01:31 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 cgroup1_get_tree
2026/08/30 14:40 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 cgroup1_get_tree
2026/08/30 11:12 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 cgroup1_get_tree
2026/08/30 01:58 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 cgroup1_get_tree
2026/08/29 16:51 linux-next e30626823a40 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/27 08:58 linux-next f82a5da2f049 a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/25 04:32 linux-next 4b18edbd8e70 23caa175 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/24 16:55 linux-next 4b18edbd8e70 23caa175 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/24 11:37 linux-next 903c1cf6dff9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/24 09:50 linux-next 903c1cf6dff9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/23 18:39 linux-next 903c1cf6dff9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/23 13:44 linux-next 903c1cf6dff9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/05/31 22:14 linux-next f7af91adc230 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/10/12 05:25 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 71c3e5409eef 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in cgroup1_get_tree
2026/10/05 02:47 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci fe98fb51bf62 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in cgroup1_get_tree
2026/10/04 14:44 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci fe98fb51bf62 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in cgroup1_get_tree
2026/10/04 04:15 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci fe98fb51bf62 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in cgroup1_get_tree
2026/09/13 22:46 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in cgroup1_get_tree
2026/09/06 11:31 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux master 0f23d56f17fd 4f7b22a0 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm32 INFO: task hung in cgroup1_get_tree
* Struck through repros no longer work on HEAD.