[v5.15] INFO: task hung in cgroup_mkdir
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syzbot
Nov 5, 2025, 3:41:24 AM (5 days ago) Nov 5
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=145e8a92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=08be379ec12c5c8f8d22
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ed7568bc5bb4/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e343e0aaac77/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/089870f2a980/bzImage-cc5ec876.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+08be37...@syzkaller.appspotmail.com
INFO: task syz-executor:4184 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:21824 pid: 4184 ppid: 4179 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
__mutex_lock_common+0xc71/0x2390 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
cgroup_kn_lock_live+0xee/0x230 kernel/cgroup/cgroup.c:1662
cgroup_mkdir+0xaf/0xe60 kernel/cgroup/cgroup.c:5579
kernfs_iop_mkdir+0x24c/0x3d0 fs/kernfs/dir.c:1175
vfs_mkdir+0x387/0x570 fs/namei.c:4073
do_mkdirat+0x1d7/0x5a0 fs/namei.c:4098
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4708fe2e17
RSP: 002b:00007fff46541368 EFLAGS: 00000202 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fff465413c0 RCX: 00007f4708fe2e17
RDX: 00000000000001ff RSI: 00007fff465413c0 RDI: 00000000ffffff9c
RBP: 0000000000000001 R08: 0000000000000017 R09: 00007fff465410b7
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007fff46541838 R15: 0000000000000000
</TASK>
INFO: task syz-executor:4189 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:21344 pid: 4189 ppid: 4181 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
rwsem_down_write_slowpath+0xc46/0x11f0 kernel/locking/rwsem.c:1165
mmap_write_lock include/linux/mmap_lock.h:71 [inline]
mpol_rebind_mm+0x33/0x2c0 mm/mempolicy.c:381
cpuset_attach+0x330/0x5f0 kernel/cgroup/cpuset.c:2376
cgroup_migrate_execute+0x7eb/0x1010 kernel/cgroup/cgroup.c:2597
cgroup_attach_task+0x562/0x7e0 kernel/cgroup/cgroup.c:2892
__cgroup1_procs_write+0x2e5/0x3f0 kernel/cgroup/cgroup-v1.c:527
cgroup_file_write+0x2f7/0x630 kernel/cgroup/cgroup.c:3966
kernfs_fop_write_iter+0x379/0x4c0 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2173 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x712/0xd00 fs/read_write.c:594
ksys_write+0x14d/0x250 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f2b8ae4817f
RSP: 002b:00007ffdde2d8d00 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f2b8ae4817f
RDX: 0000000000000001 RSI: 00007ffdde2d8d50 RDI: 0000000000000003
RBP: 00007ffdde2d92c0 R08: 0000000000000000 R09: 00007ffdde2d8b57
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007ffdde2d8d50 R14: 00007ffdde2d9280 R15: 00007ffdde2d92c0
</TASK>
INFO: task udevd:4289 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd state:D stack:26304 pid: 4289 ppid: 3561 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
percpu_rwsem_wait+0x2d8/0x310 kernel/locking/percpu-rwsem.c:160
__percpu_down_read+0xc9/0x100 kernel/locking/percpu-rwsem.c:174
percpu_down_read include/linux/percpu-rwsem.h:65 [inline]
cgroup_threadgroup_change_begin include/linux/cgroup-defs.h:724 [inline]
exit_signals+0x3e5/0x510 kernel/signal.c:2991
do_exit+0x256/0x20a0 kernel/exit.c:830
do_group_exit+0x12e/0x300 kernel/exit.c:997
__do_sys_exit_group kernel/exit.c:1008 [inline]
__se_sys_exit_group kernel/exit.c:1006 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f41de22c6c5
RSP: 002b:00007ffc5fe0ff68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000055cf2aad33f0 RCX: 00007f41de22c6c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 000055cf2aa97910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc5fe0ffb0 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:1/144:
#0: ffff8880b913a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
#1: ffff8880b9127888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x495/0x810 kernel/sched/psi.c:882
1 lock held by udevd/3561:
#0: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: copy_process+0x2290/0x3e00 kernel/fork.c:2382
2 locks held by dhcpcd/3854:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
2 locks held by getty/3949:
#0: ffff88814cff0098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz-executor/4178:
#0: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x256/0x20a0 kernel/exit.c:830
2 locks held by syz-executor/4183:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
3 locks held by syz-executor/4184:
#0: ffff88807dfa8460 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
#1: ffff888074f6c150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
#1: ffff888074f6c150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: filename_create+0x1f2/0x450 fs/namei.c:3843
#2: ffffffff8c142008 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xee/0x230 kernel/cgroup/cgroup.c:1662
2 locks held by syz-executor/4185:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
7 locks held by syz-executor/4189:
#0: ffff888079c6a460 (sb_writers#11){.+.+}-{0:0}, at: vfs_write+0x28a/0xd00 fs/read_write.c:590
#1: ffff88805f689888 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e5/0x4c0 fs/kernfs/file.c:287
#2: ffffffff8c142008 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xee/0x230 kernel/cgroup/cgroup.c:1662
#3: ffffffff8bfbaed0 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2411 [inline]
#3: ffffffff8bfbaed0 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_procs_write_start+0x17c/0x580 kernel/cgroup/cgroup.c:2921
#4: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2413 [inline]
#4: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_procs_write_start+0x192/0x580 kernel/cgroup/cgroup.c:2921
#5: ffffffff8c14fb48 (cpuset_mutex){+.+.}-{3:3}, at: cpuset_attach+0xac/0x5f0 kernel/cgroup/cpuset.c:2348
#6: ffff888029fe9628 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
#6: ffff888029fe9628 (&mm->mmap_lock){++++}-{3:3}, at: mpol_rebind_mm+0x33/0x2c0 mm/mempolicy.c:381
2 locks held by syz-executor/4191:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
1 lock held by udevd/4289:
#0: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x256/0x20a0 kernel/exit.c:830
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0xe0f/0xe50 kernel/hung_task.c:369
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 154 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: phy8 ieee80211_iface_work
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0xc/0x80 kernel/kcov.c:279
Code: 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 0f 1f 44 00 00 48 8b 04 24 65 48 8b 0d 44 a1 8a 7e <65> 8b 15 45 a1 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75
RSP: 0018:ffffc90001e67570 EFLAGS: 00000247
RAX: ffffffff891a8718 RBX: 0000000000000001 RCX: ffff88801b9dbb80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90001e67850 R08: dffffc0000000000 R09: fffffbfff1ad33a6
R10: fffffbfff1ad33a6 R11: 1ffffffff1ad33a5 R12: ffff8880600ea050
R13: ffff88802319b550 R14: 0000000000000001 R15: 000000000000004c
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cf2aaa0a38 CR3: 000000007de20000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
variable_test_bit arch/x86/include/asm/bitops.h:214 [inline]
test_bit include/asm-generic/bitops/instrumented-non-atomic.h:135 [inline]
cpumask_test_cpu include/linux/cpumask.h:344 [inline]
cpu_online include/linux/cpumask.h:895 [inline]
trace_cfg80211_return_bss+0x68/0x1c0 net/wireless/trace.h:3341
cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2570 [inline]
cfg80211_inform_bss_frame_data+0xa21/0x1f30 net/wireless/scan.c:2588
ieee80211_bss_info_update+0x6c2/0xaa0 net/mac80211/scan.c:190
ieee80211_rx_bss_info net/mac80211/ibss.c:1123 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1614 [inline]
ieee80211_ibss_rx_queued_mgmt+0x16d0/0x29c0 net/mac80211/ibss.c:1643
ieee80211_iface_process_skb net/mac80211/iface.c:1459 [inline]
ieee80211_iface_work+0x70e/0xc60 net/mac80211/iface.c:1513
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=145e8a92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=08be379ec12c5c8f8d22
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ed7568bc5bb4/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e343e0aaac77/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/089870f2a980/bzImage-cc5ec876.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+08be37...@syzkaller.appspotmail.com
INFO: task syz-executor:4184 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:21824 pid: 4184 ppid: 4179 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
__mutex_lock_common+0xc71/0x2390 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
cgroup_kn_lock_live+0xee/0x230 kernel/cgroup/cgroup.c:1662
cgroup_mkdir+0xaf/0xe60 kernel/cgroup/cgroup.c:5579
kernfs_iop_mkdir+0x24c/0x3d0 fs/kernfs/dir.c:1175
vfs_mkdir+0x387/0x570 fs/namei.c:4073
do_mkdirat+0x1d7/0x5a0 fs/namei.c:4098
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4708fe2e17
RSP: 002b:00007fff46541368 EFLAGS: 00000202 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fff465413c0 RCX: 00007f4708fe2e17
RDX: 00000000000001ff RSI: 00007fff465413c0 RDI: 00000000ffffff9c
RBP: 0000000000000001 R08: 0000000000000017 R09: 00007fff465410b7
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007fff46541838 R15: 0000000000000000
</TASK>
INFO: task syz-executor:4189 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:21344 pid: 4189 ppid: 4181 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
rwsem_down_write_slowpath+0xc46/0x11f0 kernel/locking/rwsem.c:1165
mmap_write_lock include/linux/mmap_lock.h:71 [inline]
mpol_rebind_mm+0x33/0x2c0 mm/mempolicy.c:381
cpuset_attach+0x330/0x5f0 kernel/cgroup/cpuset.c:2376
cgroup_migrate_execute+0x7eb/0x1010 kernel/cgroup/cgroup.c:2597
cgroup_attach_task+0x562/0x7e0 kernel/cgroup/cgroup.c:2892
__cgroup1_procs_write+0x2e5/0x3f0 kernel/cgroup/cgroup-v1.c:527
cgroup_file_write+0x2f7/0x630 kernel/cgroup/cgroup.c:3966
kernfs_fop_write_iter+0x379/0x4c0 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2173 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x712/0xd00 fs/read_write.c:594
ksys_write+0x14d/0x250 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f2b8ae4817f
RSP: 002b:00007ffdde2d8d00 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f2b8ae4817f
RDX: 0000000000000001 RSI: 00007ffdde2d8d50 RDI: 0000000000000003
RBP: 00007ffdde2d92c0 R08: 0000000000000000 R09: 00007ffdde2d8b57
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007ffdde2d8d50 R14: 00007ffdde2d9280 R15: 00007ffdde2d92c0
</TASK>
INFO: task udevd:4289 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd state:D stack:26304 pid: 4289 ppid: 3561 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
percpu_rwsem_wait+0x2d8/0x310 kernel/locking/percpu-rwsem.c:160
__percpu_down_read+0xc9/0x100 kernel/locking/percpu-rwsem.c:174
percpu_down_read include/linux/percpu-rwsem.h:65 [inline]
cgroup_threadgroup_change_begin include/linux/cgroup-defs.h:724 [inline]
exit_signals+0x3e5/0x510 kernel/signal.c:2991
do_exit+0x256/0x20a0 kernel/exit.c:830
do_group_exit+0x12e/0x300 kernel/exit.c:997
__do_sys_exit_group kernel/exit.c:1008 [inline]
__se_sys_exit_group kernel/exit.c:1006 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f41de22c6c5
RSP: 002b:00007ffc5fe0ff68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000055cf2aad33f0 RCX: 00007f41de22c6c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 000055cf2aa97910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc5fe0ffb0 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:1/144:
#0: ffff8880b913a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
#1: ffff8880b9127888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x495/0x810 kernel/sched/psi.c:882
1 lock held by udevd/3561:
#0: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: copy_process+0x2290/0x3e00 kernel/fork.c:2382
2 locks held by dhcpcd/3854:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888025075c28 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
2 locks held by getty/3949:
#0: ffff88814cff0098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz-executor/4178:
#0: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x256/0x20a0 kernel/exit.c:830
2 locks held by syz-executor/4183:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888075d16a28 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
3 locks held by syz-executor/4184:
#0: ffff88807dfa8460 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
#1: ffff888074f6c150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
#1: ffff888074f6c150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: filename_create+0x1f2/0x450 fs/namei.c:3843
#2: ffffffff8c142008 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xee/0x230 kernel/cgroup/cgroup.c:1662
2 locks held by syz-executor/4185:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888075d17128 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
7 locks held by syz-executor/4189:
#0: ffff888079c6a460 (sb_writers#11){.+.+}-{0:0}, at: vfs_write+0x28a/0xd00 fs/read_write.c:590
#1: ffff88805f689888 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e5/0x4c0 fs/kernfs/file.c:287
#2: ffffffff8c142008 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xee/0x230 kernel/cgroup/cgroup.c:1662
#3: ffffffff8bfbaed0 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2411 [inline]
#3: ffffffff8bfbaed0 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_procs_write_start+0x17c/0x580 kernel/cgroup/cgroup.c:2921
#4: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2413 [inline]
#4: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_procs_write_start+0x192/0x580 kernel/cgroup/cgroup.c:2921
#5: ffffffff8c14fb48 (cpuset_mutex){+.+.}-{3:3}, at: cpuset_attach+0xac/0x5f0 kernel/cgroup/cpuset.c:2348
#6: ffff888029fe9628 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
#6: ffff888029fe9628 (&mm->mmap_lock){++++}-{3:3}, at: mpol_rebind_mm+0x33/0x2c0 mm/mempolicy.c:381
2 locks held by syz-executor/4191:
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:503 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1466 [inline]
#0: ffffffff8c1a68f0 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x21f/0x1380 kernel/fork.c:1518
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:504 [inline]
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1466 [inline]
#1: ffff888029fe8f28 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x238/0x1380 kernel/fork.c:1518
1 lock held by udevd/4289:
#0: ffffffff8c1421f0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x256/0x20a0 kernel/exit.c:830
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0xe0f/0xe50 kernel/hung_task.c:369
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 154 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: phy8 ieee80211_iface_work
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0xc/0x80 kernel/kcov.c:279
Code: 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 0f 1f 44 00 00 48 8b 04 24 65 48 8b 0d 44 a1 8a 7e <65> 8b 15 45 a1 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75
RSP: 0018:ffffc90001e67570 EFLAGS: 00000247
RAX: ffffffff891a8718 RBX: 0000000000000001 RCX: ffff88801b9dbb80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90001e67850 R08: dffffc0000000000 R09: fffffbfff1ad33a6
R10: fffffbfff1ad33a6 R11: 1ffffffff1ad33a5 R12: ffff8880600ea050
R13: ffff88802319b550 R14: 0000000000000001 R15: 000000000000004c
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cf2aaa0a38 CR3: 000000007de20000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
variable_test_bit arch/x86/include/asm/bitops.h:214 [inline]
test_bit include/asm-generic/bitops/instrumented-non-atomic.h:135 [inline]
cpumask_test_cpu include/linux/cpumask.h:344 [inline]
cpu_online include/linux/cpumask.h:895 [inline]
trace_cfg80211_return_bss+0x68/0x1c0 net/wireless/trace.h:3341
cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2570 [inline]
cfg80211_inform_bss_frame_data+0xa21/0x1f30 net/wireless/scan.c:2588
ieee80211_bss_info_update+0x6c2/0xaa0 net/mac80211/scan.c:190
ieee80211_rx_bss_info net/mac80211/ibss.c:1123 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1614 [inline]
ieee80211_ibss_rx_queued_mgmt+0x16d0/0x29c0 net/mac80211/ibss.c:1643
ieee80211_iface_process_skb net/mac80211/iface.c:1459 [inline]
ieee80211_iface_work+0x70e/0xc60 net/mac80211/iface.c:1513
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
---
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