syzbot

INFO: task syz.4.36:6172 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.36        state:D stack:24552 pid:6172  tgid:6171  ppid:5813   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 percpu_rwsem_wait+0x2e6/0x330 kernel/locking/percpu-rwsem.c:164
 __percpu_down_read+0xfc/0x140 kernel/locking/percpu-rwsem.c:180
 percpu_down_read_internal include/linux/percpu-rwsem.h:67 [inline]
 percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 __sb_start_write include/linux/fs.h:1916 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs.h:2052
 mnt_want_write+0x41/0x90 fs/namespace.c:508
 filename_create+0x148/0x3c0 fs/namei.c:4219
 do_mkdirat+0xa0/0x590 fs/namei.c:4478
 __do_sys_mkdirat fs/namei.c:4503 [inline]
 __se_sys_mkdirat fs/namei.c:4501 [inline]
 __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4501
 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: 0033:0x7f21968cd617
RSP: 002b:00007f2194b2de68 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f2194b2def0 RCX: 00007f21968cd617
RDX: 00000000000001ff RSI: 0000200000000200 RDI: 00000000ffffff9c
RBP: 00002000000001c0 R08: 0000200000000580 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000200000000200
R13: 00007f2194b2deb0 R14: 0000000000000000 R15: 0000200000000400
 </TASK>
INFO: task syz.4.36:6176 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.36        state:D stack:26328 pid:6176  tgid:6171  ppid:5813   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 percpu_rwsem_wait+0x2e6/0x330 kernel/locking/percpu-rwsem.c:164
 __percpu_down_read+0xfc/0x140 kernel/locking/percpu-rwsem.c:180
 percpu_down_read_internal include/linux/percpu-rwsem.h:67 [inline]
 percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 __sb_start_write include/linux/fs.h:1916 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs.h:2052
 mnt_want_write+0x41/0x90 fs/namespace.c:508
 filename_create+0x148/0x3c0 fs/namei.c:4219
 do_mkdirat+0xa0/0x590 fs/namei.c:4478
 __do_sys_mkdirat fs/namei.c:4503 [inline]
 __se_sys_mkdirat fs/namei.c:4501 [inline]
 __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4501
 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: 0033:0x7f21968cd617
RSP: 002b:00007f2194aebe68 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f2194aebef0 RCX: 00007f21968cd617
RDX: 00000000000001ff RSI: 0000200000000180 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000180
R13: 00007f2194aebeb0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/38:
 #0: ffffffff8d7aa4c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8d7aa4c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8d7aa4c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:2/43:
 #0: ffff88814d715938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
 #0: ffff88814d715938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
 #1: ffffc90000b47ba0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
 #1: ffffc90000b47ba0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
 #2: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x119/0x15a0 net/ipv6/addrconf.c:4194
5 locks held by kworker/u8:6/1178:
2 locks held by dhcpcd/5463:
 #0: ffffffff8ea5c8d8 (vlan_ioctl_mutex){+.+.}-{4:4}, at: sock_ioctl+0x5f1/0x790 net/socket.c:1337
 #1: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: vlan_ioctl_handler+0xd0/0x650 net/8021q/vlan.c:577
2 locks held by getty/5563:
 #0: ffff88823bf3e8a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1400 drivers/tty/n_tty.c:2222
13 locks held by syz-executor/5788:
1 lock held by syz.4.36/6172:
 #0: ffff88806292a480 (sb_writers#20){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:508
1 lock held by syz.4.36/6176:
 #0: ffff88806292a480 (sb_writers#20){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:508
2 locks held by syz-executor/6794:
1 lock held by syz-executor/7147:
 #0: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x5b7/0xd20 net/ipv6/addrconf.c:5027
1 lock held by syz-executor/7299:
 #0: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #0: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8e9/0x1c80 net/core/rtnetlink.c:4064
2 locks held by syz-executor/7336:
 #0: ffffffff8ea6b560 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x337/0x4e0 net/core/net_namespace.c:576
 #1: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: register_nexthop_notifier+0x80/0x210 net/ipv4/nexthop.c:3971
2 locks held by syz-executor/7339:
 #0: ffffffff8ea6b560 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x337/0x4e0 net/core/net_namespace.c:576
 #1: ffffffff8ea78478 (rtnl_mutex){+.+.}-{4:4}, at: register_nexthop_notifier+0x80/0x210 net/ipv4/nexthop.c:3971

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 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
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6794 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:class_preempt_destructor include/linux/preempt.h:470 [inline]
RIP: 0010:__migrate_disable include/linux/sched.h:2397 [inline]
RIP: 0010:migrate_disable include/linux/sched.h:2412 [inline]
RIP: 0010:__rt_spin_lock kernel/locking/spinlock_rt.c:51 [inline]
RIP: 0010:rt_spin_lock+0x2a4/0x3e0 kernel/locking/spinlock_rt.c:57
Code: 91 4c 89 f0 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 0b 01 00 00 41 ff 06 43 0f b6 04 2f 84 c0 0f 85 19 01 00 00 66 c7 03 01 00 <bf> 01 00 00 00 e8 d2 fd c6 f6 65 8b 05 fb a3 fc 06 85 c0 74 59 48
RSP: 0018:ffffc90005f77800 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888023f98480 RCX: ffffffff98d0d300
RDX: 0000000000000000 RSI: ffffffff8b3f5440 RDI: ffffffff8ac8fbec
RBP: ffffc90005f778b0 R08: 0000000000000000 R09: ffffffff8ac8fb41
R10: dffffc0000000000 R11: fffffbfff1deee4f R12: 1ffff92000beef09
R13: dffffc0000000000 R14: ffff8880b893bba0 R15: 1ffff110047f3090
FS:  000055556a66b500(0000) GS:ffff888126cc6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fea09b95000 CR3: 0000000058162000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 f2fs_sync_inode_meta fs/f2fs/checkpoint.c:1142 [inline]
 block_operations fs/f2fs/checkpoint.c:1263 [inline]
 f2fs_write_checkpoint+0xa9a/0x2440 fs/f2fs/checkpoint.c:1678
 kill_f2fs_super+0x2cc/0x6d0 fs/f2fs/super.c:5448
 deactivate_locked_super+0xbc/0x130 fs/super.c:473
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1327
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f749a9101f7
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffd723f9b18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f749a991d7d RCX: 00007f749a9101f7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd723f9bd0
RBP: 00007ffd723f9bd0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffd723fac60
R13: 00007f749a991d7d R14: 000000000003d00b R15: 00007ffd723faca0
 </TASK>