INFO: task kworker/u8:3:49 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:3 state:D stack:20792 pid:49 tgid:49 ppid:2 task_flags:0x4388060 flags:0x00080000
Workqueue: loop6 loop_rootcg_workfn
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7026
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
rwsem_down_read_slowpath+0x5fd/0x8f0 kernel/locking/rwsem.c:1086
__down_read_common kernel/locking/rwsem.c:1261 [inline]
__down_read kernel/locking/rwsem.c:1274 [inline]
down_read+0x98/0x2e0 kernel/locking/rwsem.c:1539
inode_lock_shared include/linux/fs.h:995 [inline]
blkdev_read_iter+0x2f8/0x440 block/fops.c:858
lo_rw_aio+0xcfa/0xfa0 include/linux/percpu-rwsem.h:-1
do_req_filebacked drivers/block/loop.c:-1 [inline]
loop_handle_cmd drivers/block/loop.c:1923 [inline]
loop_process_work+0x835/0xf90 drivers/block/loop.c:1958
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
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
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8df3d6e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8df3d6e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8df3d6e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:3/49:
#0: ffff8880292fa948 ((wq_completion)loop6){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff8880292fa948 ((wq_completion)loop6){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc90000ba7ba0 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc90000ba7ba0 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffff8880229163a8 (&sb->s_type->i_mutex_key#8){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:995 [inline]
#2: ffff8880229163a8 (&sb->s_type->i_mutex_key#8){++++}-{4:4}, at: blkdev_read_iter+0x2f8/0x440 block/fops.c:858
2 locks held by getty/5592:
#0: ffff8880336050a0 (&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
1 lock held by udevd/5887:
#0: ffff888022901328 (&sb->s_type->i_mutex_key#8){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:995 [inline]
#0: ffff888022901328 (&sb->s_type->i_mutex_key#8){++++}-{4:4}, at: blkdev_read_iter+0x2f8/0x440 block/fops.c:858
1 lock held by syz-executor/9538:
2 locks held by syz.0.1106/9890:
1 lock held by syz.5.1433/11065:
#0: ffff888022916548 (mapping.invalidate_lock){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1045 [inline]
#0: ffff888022916548 (mapping.invalidate_lock){++++}-{4:4}, at: page_cache_ra_order+0x3a2/0xe70 mm/readahead.c:494
2 locks held by syz.5.1433/11073:
#0: ffff88807af9e860 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1679 [inline]
#0: ffff88807af9e860 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x21/0x50 net/ipv4/tcp.c:1412
#1: ffff888022916548 (mapping.invalidate_lock){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1045 [inline]
#1: ffff888022916548 (mapping.invalidate_lock){++++}-{4:4}, at: page_cache_ra_order+0x3a2/0xe70 mm/readahead.c:494
1 lock held by dhcpcd-run-hook/12252:
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
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:332 [inline]
watchdog+0xf60/0xfa0 kernel/hung_task.c:495
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
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 12255 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:find_stack lib/stackdepot.c:602 [inline]
RIP: 0010:stack_depot_save_flags+0x1ab/0x860 lib/stackdepot.c:668
Code: 02 00 00 31 f6 4c 89 54 24 18 e8 80 04 c8 ff 4c 8b 54 24 18 8b 74 24 04 85 db 75 5d 4d 8b 3f 4d 39 e7 74 52 41 39 6f 10 75 f2 <45> 39 57 14 75 ec 31 c0 49 8b 0c c6 49 3b 4c c7 20 75 df 48 ff c0
RSP: 0018:ffffc9000cfaf1a8 EFLAGS: 00000246
RAX: ffff88823ae00000 RBX: 0000000000000000 RCX: 0000000000d58620
RDX: 000000009db1f13b RSI: 0000000000000000 RDI: 00000000c2ecf8a1
RBP: 0000000089cd5862 R08: 000000002fd4a93c R09: 00000000f345475e
R10: 0000000000000010 R11: ffffffff81ac2e10 R12: ffff88823bb58620
R13: 0000000000000010 R14: ffffc9000cfaf210 R15: ffff88807c55c000
FS: 0000000000000000(0000) GS:ffff888126139000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d875504950 CR3: 0000000075d92000 CR4: 00000000003526f0
Call Trace:
kasan_save_stack+0x4d/0x60 mm/kasan/common.c:57
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559
slab_free_hook mm/slub.c:2504 [inline]
slab_free mm/slub.c:6642 [inline]
kmem_cache_free+0x4a2/0x690 mm/slub.c:6752
anon_vma_free mm/rmap.c:136 [inline]
__put_anon_vma+0x12b/0x2d0 mm/rmap.c:2777
put_anon_vma include/linux/rmap.h:117 [inline]
unlink_anon_vmas+0x503/0x670 mm/rmap.c:443
free_pgtables+0x72b/0x9c0 mm/memory.c:414
exit_mmap+0x43c/0xb40 mm/mmap.c:1291
__mmput+0x118/0x430 kernel/fork.c:1133
exec_mmap+0x6ac/0x7d0 fs/exec.c:901
begin_new_exec+0x12d6/0x2160 fs/exec.c:1156
load_elf_binary+0x998/0x2740 fs/binfmt_elf.c:1010
search_binary_handler fs/exec.c:1670 [inline]
exec_binprm fs/exec.c:1702 [inline]
bprm_execve+0x99c/0x1450 fs/exec.c:1754
do_execveat_common+0x510/0x6a0 fs/exec.c:1860
do_execve fs/exec.c:1934 [inline]
__do_sys_execve fs/exec.c:2010 [inline]
__se_sys_execve fs/exec.c:2005 [inline]
__x64_sys_execve+0x94/0xb0 fs/exec.c:2005
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: 0033:0x7fb84a765107
Code: Unable to access opcode bytes at 0x7fb84a7650dd.
RSP: 002b:00007fff9d994778 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 000055d875515190 RCX: 00007fb84a765107
RDX: 000055d8755151b8 RSI: 000055d875515190 RDI: 000055d875515270
RBP: 000055d875515270 R08: 00007fff9d999e0c R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 000055d8755151b8
R13: 00007fb84a92ae8b R14: 000055d8755151b8 R15: 0000000000000000