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: 89d, last: 1d00h
✨ AI Jobs (1)
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.1.5363:27420 blocked for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.5363      state:D stack:28456 pid:27420 tgid:27417 ppid:24928  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7326
 cgroup_lock_and_drain_offline+0x51a/0x650 kernel/cgroup/cgroup.c:3275
 cgroup1_get_tree+0x9d/0x890 kernel/cgroup/cgroup-v1.c:1265
 vfs_get_tree+0x92/0x2a0 fs/super.c:1700
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3841
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb32639e0d9
RSP: 002b:00007fb327249028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb326625fa0 RCX: 00007fb32639e0d9
RDX: 00002000000001c0 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007fb326435024 R08: 0000200000000000 R09: 0000000000000000
R10: 0000000002010042 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb326626038 R14: 00007fb326625fa0 R15: 00007ffc3b23e328
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
1 lock held by udevd/4972:
2 locks held by getty/5362:
 #0: ffff8880357300a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
2 locks held by syz-executor/27704:
3 locks held by udevd/28428:
 #0: ffff8880b863b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb2/0x160 kernel/sched/core.c:675
 #1: ffff8880b8624440 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x57/0x7d0 kernel/sched/psi.c:933
 #2: ffff888028b26980 (&____s->seqcount#8){....}-{0:0}, at: ep_send_events fs/eventpoll.c:2168 [inline]
 #2: ffff888028b26980 (&____s->seqcount#8){....}-{0:0}, at: ep_try_send_events+0xb97/0xd50 fs/eventpoll.c:2224
2 locks held by syz.3.5994/29515:
1 lock held by syz.3.6038/29641:
4 locks held by syz.6.6039/29652:

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

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 07/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
 nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [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+0x388/0x470 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: 29515 Comm: syz.3.5994 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:81 [inline]
RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:103 [inline]
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:238 [inline]
RIP: 0010:unwind_next_frame+0x4fb/0x2550 arch/x86/kernel/unwind_orc.c:510
Code: c1 e8 3f 48 01 c8 48 83 e0 fe 49 8d 1c 47 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 27 48 63 03 <48> 01 d8 48 8d 4b 04 48 39 e8 4c 0f 46 f9 48 8d 43 fc 4c 0f 47 e0
RSP: 0018:ffffc90005115fe0 EFLAGS: 00000246
RAX: fffffffff1ec93d5 RBX: ffffffff907d3b44 RCX: dffffc0000000000
RDX: ffffffff907d3b44 RSI: ffffffff9101490c RDI: ffffffff8c4bbe20
RBP: ffffffff826a01be R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: ffffffff907d3b44
R13: ffffffff907d3b44 R14: ffffc90005116088 R15: ffffffff907d3b44
FS:  00007fa4b5de36c0(0000) GS:ffff888124f49000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feadc5ef2f8 CR3: 0000000079ce9000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof+0x39/0x160 mm/mempolicy.c:2509
 shmem_alloc_folio mm/shmem.c:1917 [inline]
 shmem_alloc_and_add_folio+0x43e/0xf60 mm/shmem.c:1959
 shmem_get_folio_gfp+0x5da/0x16d0 mm/shmem.c:2512
 shmem_get_folio mm/shmem.c:2618 [inline]
 shmem_write_begin+0x16c/0x330 mm/shmem.c:3249
 generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4364
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3424
 __kernel_write_iter+0x44a/0x8f0 fs/read_write.c:621
 dump_emit_page fs/coredump.c:1298 [inline]
 dump_user_range+0xc19/0x12c0 fs/coredump.c:1372
 elf_core_dump+0x3485/0x3a90 fs/binfmt_elf.c:2109
 coredump_write+0x1290/0x1960 fs/coredump.c:1052
 do_coredump fs/coredump.c:1131 [inline]
 vfs_coredump+0x36ff/0x44b0 fs/coredump.c:1200
 get_signal+0x1094/0x12c0 kernel/signal.c:3031
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:101 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x2ba/0x8f0 kernel/entry/common.c:165
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x7fa4b4f9e0e1
Code: 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 48 3d 01 f0 ff ff 73 01 <c3> 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:0000000000000050 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fa4b5225fa0 RCX: 00007fa4b4f9e0d9
RDX: 0000000000000000 RSI: 0000000000000050 RDI: 0000000000000000
RBP: 00007fa4b5035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa4b5226038 R14: 00007fa4b5225fa0 R15: 00007ffd9e328f88
 </TASK>

Crashes (211):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/17 04:48 upstream dcb68831eac7 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/13 10:28 upstream 3d6d817622b0 67796a05 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/08/11 20:22 upstream d58772d8520c 37a258dd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in cgroup1_get_tree
2026/08/10 04:14 upstream b643e495ae92 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/08 00:41 upstream 364465ab19de e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/04 23:38 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/04 07:01 upstream c8e0d43058e6 a68cb31b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/03 04:10 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/08/02 18:48 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/08/02 13:32 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in cgroup1_get_tree
2026/08/02 10:24 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/08/02 08:05 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in cgroup1_get_tree
2026/08/01 18:35 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/07/31 16:41 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/07/30 19:27 upstream 11028ab62899 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/07/29 23:52 upstream fc02acf6ac0c cb1587ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/07/29 07:45 upstream 3b5f4b83c4ab 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/07/28 16:10 upstream 62cc90241548 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/07/27 06:38 upstream 4235cb24ec1e 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/27 03:53 upstream 4235cb24ec1e 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/26 20:15 upstream 3dab139d4795 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/07/26 19:02 upstream 3dab139d4795 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in cgroup1_get_tree
2026/07/25 19:40 upstream 0ce37745d4bf 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/07/25 05:11 upstream 48a5a7ab8d6a 05b26a28 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/07/24 11:28 upstream d326f83e819c 544adce9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/23 17:46 upstream 4539944e5151 71a13572 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/07/23 08:35 upstream 4539944e5151 881ce5c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/22 16:24 upstream 248951ddc14d b561ce9c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in cgroup1_get_tree
2026/07/22 14:09 upstream 248951ddc14d b561ce9c .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
2026/07/24 13:57 upstream d326f83e819c 544adce9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: task hung in cgroup1_get_tree
2026/08/19 02:37 linux-next 5453bc3279e9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/18 08:09 linux-next e6664f2b33db 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/16 13:15 linux-next 4477a78374a5 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/12 12:43 linux-next cc2b5f627e8c f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/10 02:56 linux-next 6b8c8af514d7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/10 02:54 linux-next cc2b5f627e8c 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/10 00:23 linux-next 6b8c8af514d7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/09 18:21 linux-next cc2b5f627e8c 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/09 11:44 linux-next 6b8c8af514d7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in cgroup1_get_tree
2026/08/08 18:02 linux-next cc2b5f627e8c 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/03 14:06 linux-next cc2b5f627e8c e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/02 00:00 linux-next cc2b5f627e8c e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/08/01 21:44 linux-next cc2b5f627e8c e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/29 11:10 linux-next cc2b5f627e8c 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/26 12:19 linux-next cc2b5f627e8c 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/26 00:12 linux-next cc2b5f627e8c 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in cgroup1_get_tree
2026/07/23 04:47 linux-next cc2b5f627e8c 881ce5c2 .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
2026/08/06 18:44 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7235a3e71949 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in cgroup1_get_tree
2026/07/28 21:31 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 365f9c7a6b81 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in cgroup1_get_tree
* Struck through repros no longer work on HEAD.