syzbot

INFO: task syz.4.303:9076 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.303       state:D stack:24824 pid:9076  tgid:9075  ppid:7912   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x147b/0x4f50 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:6960
 percpu_rwsem_wait+0x2f7/0x340 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/super.h:19 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs/super.h:125
 mnt_want_write+0x41/0x90 fs/namespace.c:499
 filename_create+0x154/0x370 fs/namei.c:4881
 do_mknodat+0x189/0x630 fs/namei.c:5035
 __do_sys_mknod fs/namei.c:5085 [inline]
 __se_sys_mknod fs/namei.c:5083 [inline]
 __x64_sys_mknod+0x8c/0xa0 fs/namei.c:5083
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe33831acb9
RSP: 002b:00007fe336576028 EFLAGS: 00000246 ORIG_RAX: 0000000000000085
RAX: ffffffffffffffda RBX: 00007fe338595fa0 RCX: 00007fe33831acb9
RDX: 0000000000000000 RSI: 0000000008001420 RDI: 0000200000000040
RBP: 00007fe338388bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe338596038 R14: 00007fe338595fa0 R15: 00007ffc21ee5018
 </TASK>
INFO: task syz.4.303:9077 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.303       state:D stack:25576 pid:9077  tgid:9075  ppid:7912   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x147b/0x4f50 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:6960
 percpu_rwsem_wait+0x2f7/0x340 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/super.h:19 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs/super.h:125
 mnt_want_write+0x41/0x90 fs/namespace.c:499
 filename_create+0x154/0x370 fs/namei.c:4881
 do_symlinkat+0x135/0x3c0 fs/namei.c:5543
 __do_sys_symlinkat fs/namei.c:5571 [inline]
 __se_sys_symlinkat fs/namei.c:5568 [inline]
 __x64_sys_symlinkat+0x95/0xb0 fs/namei.c:5568
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe33831acb9
RSP: 002b:00007fe336555028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007fe338596090 RCX: 00007fe33831acb9
RDX: 0000200000000c80 RSI: 0000000000000005 RDI: 0000200000000300
RBP: 00007fe338388bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe338596128 R14: 00007fe338596090 R15: 00007ffc21ee5018
 </TASK>
INFO: task syz.4.303:9078 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.303       state:D stack:26840 pid:9078  tgid:9075  ppid:7912   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x147b/0x4f50 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:6960
 percpu_rwsem_wait+0x2f7/0x340 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/super.h:19 [inline]
 sb_start_write+0x18e/0x1c0 include/linux/fs/super.h:125
 mnt_want_write+0x41/0x90 fs/namespace.c:499
 filename_create+0x154/0x370 fs/namei.c:4881
 do_mkdirat+0xd2/0x4c0 fs/namei.c:5165
 __do_sys_mkdirat fs/namei.c:5195 [inline]
 __se_sys_mkdirat fs/namei.c:5193 [inline]
 __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:5193
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe338319b97
RSP: 002b:00007fe336533e58 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fe336533ee0 RCX: 00007fe338319b97
RDX: 00000000000001ff RSI: 00002000000000c0 RDI: 00000000ffffff9c
RBP: 0000200000000200 R08: 0000200000000000 R09: 0000000000000000
R10: 0000200000000200 R11: 0000000000000246 R12: 00002000000000c0
R13: 00007fe336533ea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:0/12:
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc90000117bc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc90000117bc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:303
4 locks held by ksoftirqd/1/30:
1 lock held by khungtaskd/38:
 #0: ffffffff8d9ae9c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8d9ae9c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8d9ae9c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:7/1219:
4 locks held by kworker/u8:10/2259:
3 locks held by kworker/u8:14/3546:
 #0: ffff88814cd64138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88814cd64138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc9000e0f7bc0 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc9000e0f7bc0 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4734
1 lock held by dhcpcd/5462:
 #0: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x32b/0x1b30 net/ipv4/devinet.c:1120
2 locks held by getty/5555:
 #0: ffff88823bfa48a0 (&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+0x462/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by syz.4.303/9076:
 #0: ffff888054fce480 (sb_writers#14){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
1 lock held by syz.4.303/9077:
 #0: ffff888054fce480 (sb_writers#14){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
1 lock held by syz.4.303/9078:
 #0: ffff888054fce480 (sb_writers#14){++++}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
7 locks held by syz-executor/10108:
 #0: ffff888035ca2480 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2681 [inline]
 #0: ffff888035ca2480 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:682
 #1: ffff88805ca8fc78 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
 #2: ffff8880275ba0f8 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff8880275ba0f8 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x540 fs/kernfs/file.c:344
 #3: ffffffff8e52cfb8 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd7/0x370 drivers/net/netdevsim/bus.c:234
 #4: ffff8880373b10d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff8880373b10d8 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1104 [inline]
 #4: ffff8880373b10d8 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x800 drivers/base/dd.c:1302
 #5: ffff8880373b7300 (&devlink->lock_key#36){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x160 drivers/net/netdevsim/dev.c:1777
 #6: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: nsim_destroy+0xed/0x680 drivers/net/netdevsim/netdev.c:1175
1 lock held by syz-executor/10235:
 #0: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8eca8b78 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
4 locks held by syz-executor/10302:
 #0: ffff888035ca2480 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2681 [inline]
 #0: ffff888035ca2480 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:682
 #1: ffff88805d596078 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
 #2: ffff8880275ba0f8 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff8880275ba0f8 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x540 fs/kernfs/file.c:344
 #3: ffffffff8e52cfb8 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd7/0x370 drivers/net/netdevsim/bus.c:234
3 locks held by syz.5.445/10522:
 #0: ffff8880202be480 (sb_writers#15){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2681 [inline]
 #0: ffff8880202be480 (sb_writers#15){.+.+}-{0:0}, at: vfs_fallocate+0x5f9/0x7f0 fs/open.c:338
 #1: ffff88805e277210 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: xfs_ilock+0xee/0x370 fs/xfs/xfs_inode.c:149
 #2: ffff88805e2773e0 (mapping.invalidate_lock#5){++++}-{4:4}, at: xfs_ilock+0x16d/0x370 fs/xfs/xfs_inode.c:157
2 locks held by syz.3.446/10532:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xf90/0xfe0 kernel/hung_task.c:515
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 10532 Comm: syz.3.446 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:234 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4879 [inline]
RIP: 0010:__lock_acquire+0x524/0x2cf0 kernel/locking/lockdep.c:5187
Code: 00 48 83 c3 28 41 89 c4 49 39 cf 0f 8d c7 00 00 00 49 83 ff 31 0f 83 83 00 00 00 8b 03 25 ff 1f 00 00 48 0f a3 05 1c 61 5e 11 <73> 10 48 69 c0 c8 00 00 00 48 8d 88 90 13 9d 92 eb 32 83 3d 23 f1
RSP: 0018:ffffc900048b76e0 EFLAGS: 00000007
RAX: 00000000000008c0 RBX: ffff88802b610bb0 RCX: 00000000ffffffff
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88802b610be0 R08: ffffffff82279f88 R09: ffffffff8d9ae9c0
R10: dffffc0000000000 R11: fffff94000254499 R12: ffffffffffffff05
R13: ffff88802b610be0 R14: ffff88802b610000 R15: 0000000000000000
FS:  00007f440db366c0(0000) GS:ffff8881268d9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c34032f CR3: 00000000761f2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:867 [inline]
 get_mem_cgroup_from_mm+0x54/0x2d0 mm/memcontrol.c:936
 __mem_cgroup_charge+0x15/0x80 mm/memcontrol.c:4744
 mem_cgroup_charge include/linux/memcontrol.h:663 [inline]
 shmem_alloc_and_add_folio mm/shmem.c:1942 [inline]
 shmem_get_folio_gfp+0x75f/0x1a80 mm/shmem.c:2556
 shmem_get_folio mm/shmem.c:2662 [inline]
 shmem_write_begin+0x166/0x320 mm/shmem.c:3315
 generic_perform_write+0x2af/0x8b0 mm/filemap.c:4314
 shmem_file_write_iter+0xfb/0x120 mm/shmem.c:3490
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x629/0xba0 fs/read_write.c:686
 ksys_write+0x156/0x270 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f440f89b58e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f440db35da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f440db366c0 RCX: 00007f440f89b58e
RDX: 0000000001000000 RSI: 00007f4405716000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f440db35ee0 R14: 00007f440db35ea0 R15: 00007f4405716000
 </TASK>