[v6.1] INFO: task hung in path_openat (4)

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syzbot

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Nov 4, 2024, 12:51:29 AM11/4/24

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Hello,

syzbot found the following issue on:

HEAD commit: 7c15117f9468 Linux 6.1.115
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16c086a7980000
kernel config: https://syzkaller.appspot.com/x/.config?x=c9c0221b8515082d
dashboard link: https://syzkaller.appspot.com/bug?extid=0ad480e74e198cde9a85
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d43a49ab45a4/disk-7c15117f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1169a6dd6d5/vmlinux-7c15117f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cac0c99432c7/bzImage-7c15117f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0ad480...@syzkaller.appspotmail.com

INFO: task syz.4.136:5061 blocked for more than 163 seconds.
Not tainted 6.1.115-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.136 state:D stack:27064 pid:5061 ppid:4258 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x143f/0x4570 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
rwsem_down_write_slowpath+0xea1/0x14b0 kernel/locking/rwsem.c:1189
inode_lock include/linux/fs.h:758 [inline]
open_last_lookups fs/namei.c:3547 [inline]
path_openat+0x7b6/0x2e60 fs/namei.c:3780
do_filp_open+0x230/0x480 fs/namei.c:3810
do_sys_openat2+0x13b/0x4f0 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]
__x64_sys_openat+0x243/0x290 fs/open.c:1345
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc29bb7e719
RSP: 002b:00007fc29c894038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fc29bd36058 RCX: 00007fc29bb7e719
RDX: 0000000000101042 RSI: 0000000020000040 RDI: ffffffffffffff9c
RBP: 00007fc29bbf132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc29bd36058 R15: 00007ffee1e78c78
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8d32b1d0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8d32b9d0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
#0: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6510
2 locks held by getty/4005:
#0: ffff888030f13098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc900032532f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a7/0x1db0 drivers/tty/n_tty.c:2198
5 locks held by kworker/u4:7/4314:
#0: ffff888017e16938
(
(wq_completion)netns
){+.+.}-{0:0}
, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1:
ffffc9000460fd20
(net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffffffff8e4eedd0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0xf1/0xb60 net/core/net_namespace.c:566
#3: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}
, at: default_device_exit_batch+0xe5/0x9d0 net/core/dev.c:11385
#4:
ffffffff8d3305f8
(rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
(rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x4f0/0x930 kernel/rcu/tree_exp.h:962
5 locks held by kworker/0:10/4438:
#0: ffff88801f6f2d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc90004a37d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffff8881453b5190 (
&dev->mutex
){....}-{3:3}
, at: device_lock include/linux/device.h:837 [inline]
, at: hub_event+0x1fe/0x5730 drivers/usb/core/hub.c:5801
#3:
ffff8881453b84f8
(
&port_dev->status_lock
){+.+.}-{3:3}
, at: usb_lock_port drivers/usb/core/hub.c:3159 [inline]
, at: hub_port_connect drivers/usb/core/hub.c:5373 [inline]
, at: hub_port_connect_change drivers/usb/core/hub.c:5617 [inline]
, at: port_event drivers/usb/core/hub.c:5773 [inline]
, at: hub_event+0x2471/0x5730 drivers/usb/core/hub.c:5855
#4: ffff8880297a0668 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5374 [inline]
#4: ffff8880297a0668 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5617 [inline]
#4: ffff8880297a0668 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5773 [inline]
#4: ffff8880297a0668 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x249e/0x5730 drivers/usb/core/hub.c:5855
4 locks held by syz.4.136/5048:
1 lock held by syz.4.136/5061:
#0: ffff888057698198 (&type->i_mutex_dir_key#12){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
#0: ffff888057698198 (&type->i_mutex_dir_key#12){+.+.}-{3:3}, at: open_last_lookups fs/namei.c:3547 [inline]
#0: ffff888057698198 (&type->i_mutex_dir_key#12){+.+.}-{3:3}, at: path_openat+0x7b6/0x2e60 fs/namei.c:3780
2 locks held by kworker/1:12/5065:
#0: ffff888017c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc9000392fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
3 locks held by kworker/0:16/5297:
#0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc900047dfd20 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2:
ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:104
3 locks held by kworker/u4:20/5362:
#0: ffff888017c79138
((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1:
ffffc900052e7d20
(
(linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
1 lock held by syz-executor/6588:
#0:
ffffffff8e4fb128
(rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
(rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147
1 lock held by syz.6.495/6775:
#0: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147
1 lock held by syz.6.495/6776:
#0: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147
2 locks held by syz.5.496/6781:
#0: ffffffff8e55a1f0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:860
#1: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: ethnl_set_fec+0x293/0xc80 net/ethtool/fec.c:263
1 lock held by syz.7.500/6796:
#0: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e4fb128 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.1.115-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1ae/0x3f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
watchdog+0xf88/0xfd0 kernel/hung_task.c:377
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4551 Comm: kworker/u4:12 Not tainted 6.1.115-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:40 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:75 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:107 [inline]
RIP: 0010:__local_bh_disable_ip+0xd0/0x210 kernel/softirq.c:323
Code: dd 8d 00 48 c7 44 24 60 00 00 00 00 9c 8f 44 24 60 42 80 3c 23 00 74 08 4c 89 f7 e8 da dc 8d 00 48 8d 7c 24 40 4c 8b 74 24 60 <fa> 65 44 01 3d df 35 ae 7e 65 8b 05 d8 35 ae 7e 44 31 f8 a9 00 ff
RSP: 0018:ffffc900033cfa80 EFLAGS: 00000246
RAX: 0000000080000001 RBX: 1ffff92000679f5c RCX: 0000000000000000
RDX: 0000000000000040 RSI: 0000000000000201 RDI: ffffc900033cfac0
RBP: ffffc900033cfb60 R08: dffffc0000000000 R09: ffffc900033cfa60
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff92000679f54 R14: 0000000000000246 R15: 0000000000000201
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558c11b5c8 CR3: 000000007a5c1000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:125 [inline]
_raw_spin_lock_bh+0x18/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:356 [inline]
nsim_dev_trap_report drivers/net/netdevsim/dev.c:816 [inline]
nsim_dev_trap_report_work+0x69f/0xab0 drivers/net/netdevsim/dev.c:851
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
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syzbot

unread,

Dec 9, 2024, 7:44:23 AM12/9/24

to syzkaller...@googlegroups.com

syzbot has found a reproducer for the following issue on:

HEAD commit: e4d90d63d385 Linux 6.1.119
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15a55944580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5516a02be29a5649

dashboard link: https://syzkaller.appspot.com/bug?extid=0ad480e74e198cde9a85
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=179c5c0f980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11a028f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/19f991f20183/disk-e4d90d63.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/61eb5f055f38/vmlinux-e4d90d63.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0ddd97416681/bzImage-e4d90d63.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/6cfff4b2838c/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0ad480...@syzkaller.appspotmail.com

INFO: task syz-executor153:4265 blocked for more than 143 seconds.
Not tainted 6.1.119-syzkaller #0