[v6.1] INFO: task hung in do_unlinkat

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syzbot

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Dec 30, 2024, 3:52:25 AM12/30/24

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Hello,

syzbot found the following issue on:

HEAD commit: 563edd786f0a Linux 6.1.122
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1677950f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=4d23ad74b95a6ead
dashboard link: https://syzkaller.appspot.com/bug?extid=a526eb1cd43f444c16f0
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/092e3fd371c6/disk-563edd78.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e38af8a28784/vmlinux-563edd78.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e19edf883c6a/Image-563edd78.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a526eb...@syzkaller.appspotmail.com

INFO: task syz.1.8:4443 blocked for more than 144 seconds.
Tainted: G W 6.1.122-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.8 state:D stack:0 pid:4443 ppid:4302 flags:0x00000001
Call trace:
__switch_to+0x308/0x598 arch/arm64/kernel/process.c:553
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0xef4/0x1d44 kernel/sched/core.c:6558
schedule+0xc4/0x170 kernel/sched/core.c:6634
rwsem_down_write_slowpath+0xc80/0x156c kernel/locking/rwsem.c:1189
__down_write_common kernel/locking/rwsem.c:1314 [inline]
__down_write kernel/locking/rwsem.c:1323 [inline]
down_write_nested+0x90/0x94 kernel/locking/rwsem.c:1690
inode_lock_nested include/linux/fs.h:793 [inline]
do_unlinkat+0x2d0/0x70c fs/namei.c:4373
__do_sys_unlinkat fs/namei.c:4433 [inline]
__se_sys_unlinkat fs/namei.c:4426 [inline]
__arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4426
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
INFO: task syz.1.8:4451 blocked for more than 144 seconds.
Tainted: G W 6.1.122-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.8 state:D stack:0 pid:4451 ppid:4302 flags:0x00000001
Call trace:
__switch_to+0x308/0x598 arch/arm64/kernel/process.c:553
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0xef4/0x1d44 kernel/sched/core.c:6558
schedule+0xc4/0x170 kernel/sched/core.c:6634
schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:6693
rwsem_down_read_slowpath+0x534/0x858 kernel/locking/rwsem.c:1094
__down_read_common kernel/locking/rwsem.c:1261 [inline]
__down_read kernel/locking/rwsem.c:1274 [inline]
down_read+0xac/0x308 kernel/locking/rwsem.c:1522
inode_lock_shared include/linux/fs.h:768 [inline]
open_last_lookups fs/namei.c:3549 [inline]
path_openat+0x5dc/0x2548 fs/namei.c:3780
do_filp_open+0x1bc/0x3cc fs/namei.c:3810
do_sys_openat2+0x128/0x3e0 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_openat fs/open.c:1350 [inline]
__se_sys_openat fs/open.c:1345 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1345
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
4 locks held by kworker/u4:0/9:
1 lock held by rcu_tasks_kthre/12:
#0: ffff800015c65570 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x44/0xd10 kernel/rcu/tasks.h:543
1 lock held by rcu_tasks_trace/13:
#0: ffff800015c65d90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x44/0xd10 kernel/rcu/tasks.h:543
3 locks held by ksoftirqd/1/21:
1 lock held by khungtaskd/28:
#0: ffff800015c653a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
1 lock held by dhcpcd/3966:
#0: ffff8000180c4648 (rtnl_mutex){+.+.}-{3:3}, at: __netlink_dump_start+0x104/0x680 net/netlink/af_netlink.c:2287
2 locks held by getty/4051:
#0: ffff0000d63cb098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
#1: ffff80001d8302f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x414/0x1214 drivers/tty/n_tty.c:2198
2 locks held by kworker/0:8/4407:
#0: ffff0000c0021938 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x664/0x1404 kernel/workqueue.c:2265
#1: ffff800021507c20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x6a8/0x1404 kernel/workqueue.c:2267
2 locks held by syz.1.8/4437:
2 locks held by syz.1.8/4443:
#0: ffff0000c3484460 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393
#1: ffff0000f58e4188 (&type->i_mutex_dir_key#9/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline]
#1: ffff0000f58e4188 (&type->i_mutex_dir_key#9/1){+.+.}-{3:3}, at: do_unlinkat+0x2d0/0x70c fs/namei.c:4373
1 lock held by syz.1.8/4451:
#0: ffff0000f58e4188 (&type->i_mutex_dir_key#9){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:768 [inline]
#0: ffff0000f58e4188 (&type->i_mutex_dir_key#9){++++}-{3:3}, at: open_last_lookups fs/namei.c:3549 [inline]
#0: ffff0000f58e4188 (&type->i_mutex_dir_key#9){++++}-{3:3}, at: path_openat+0x5dc/0x2548 fs/namei.c:3780
4 locks held by kworker/u4:8/4951:
#0: ffff0000c03dd138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x664/0x1404 kernel/workqueue.c:2265
#1: ffff800021b07c20 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x6a8/0x1404 kernel/workqueue.c:2267
#2: ffff8000180b8710 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0xf4/0xa18 net/core/net_namespace.c:583
#3: ffff0000da9813e8 (&wg->device_update_lock){+.+.}-{3:3}, at: wg_destruct+0x11c/0x2dc drivers/net/wireguard/device.c:249
2 locks held by kworker/1:29/5815:
#0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x664/0x1404 kernel/workqueue.c:2265
#1: ffff800021977c20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x6a8/0x1404 kernel/workqueue.c:2267
1 lock held by syz.7.401/6834:
#0: ffff800015c6a880 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x58/0x5c4 kernel/rcu/tree.c:4019
2 locks held by syz.5.406/6866:
#0: ffff0000f74710b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:508 [inline]
#0: ffff0000f74710b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1f8/0x4c4 net/bluetooth/hci_core.c:2707
#1: ffff0000f7470078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x39c/0xf1c net/bluetooth/hci_sync.c:5164
1 lock held by syz.8.414/6889:
#0: ffff800015c6a880 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x58/0x5c4 kernel/rcu/tree.c:4019
1 lock held by syz-executor/6893:
1 lock held by syz-executor/6896:
#0: ffff0001b3cf3158 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:537 [inline]
#0: ffff0001b3cf3158 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1355 [inline]
#0: ffff0001b3cf3158 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1645 [inline]
#0: ffff0001b3cf3158 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x2c4/0x1d44 kernel/sched/core.c:6474
1 lock held by syz-executor/6901:
1 lock held by syz-executor/6909:
#0: ffff8000180b8710 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x2cc/0x58c net/core/net_namespace.c:494
2 locks held by dhcpcd/6933:
#0: ffff0000d7653210 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
#0: ffff0000d7653210 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:653 [inline]
#0: ffff0000d7653210 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x80/0x1fc net/socket.c:1400
#1: ffff800015c6a9b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
#1: ffff800015c6a9b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3e0/0x77c kernel/rcu/tree_exp.h:962

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

---
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.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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

unread,

Dec 30, 2024, 8:49:22 AM12/30/24

to syzkaller...@googlegroups.com

syzbot has found a reproducer for the following issue on:

HEAD commit: 563edd786f0a Linux 6.1.122
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=14edf0b0580000

kernel config: https://syzkaller.appspot.com/x/.config?x=4d23ad74b95a6ead
dashboard link: https://syzkaller.appspot.com/bug?extid=a526eb1cd43f444c16f0
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12edf0b0580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1201aac4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/092e3fd371c6/disk-563edd78.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e38af8a28784/vmlinux-563edd78.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e19edf883c6a/Image-563edd78.gz.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/4e2b59161a0c/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a526eb...@syzkaller.appspotmail.com

INFO: task syz-executor425:4318 blocked for more than 143 seconds.