------------[ cut here ]------------
WARNING: ./include/linux/ns_common.h:255 at __ns_ref_put include/linux/ns_common.h:255 [inline], CPU#0: syz.0.575/8078
WARNING: ./include/linux/ns_common.h:255 at put_user_ns include/linux/user_namespace.h:189 [inline], CPU#0: syz.0.575/8078
WARNING: ./include/linux/ns_common.h:255 at delayed_free_pidns+0x118/0x150 kernel/pid_namespace.c:145, CPU#0: syz.0.575/8078
Modules linked in:
CPU: 0 UID: 0 PID: 8078 Comm: syz.0.575 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__ns_ref_put include/linux/ns_common.h:255 [inline]
RIP: 0010:put_user_ns include/linux/user_namespace.h:189 [inline]
RIP: 0010:delayed_free_pidns+0x118/0x150 kernel/pid_namespace.c:145
Code: 85 ed 7e 2b e8 99 9f 03 00 48 83 c3 a8 48 8b 3d 5e be c7 17 48 89 de 5b 41 5c 41 5e 41 5f 5d e9 1e 1e 5f 00 e8 79 9f 03 00 90 <0f> 0b 90 eb b4 e8 6e 9f 03 00 4c 89 ff be 03 00 00 00 e8 01 fb d2
RSP: 0000:ffffc90000007bb0 EFLAGS: 00010246
RAX: ffffffff81bde0b7 RBX: ffff8880783f9078 RCX: ffff8880274c1e80
RDX: 0000000000000100 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 0000000000000002 R08: ffff88807c978193 R09: 1ffff1100f92f032
R10: dffffc0000000000 R11: ffffed100f92f033 R12: dffffc0000000000
R13: ffffffff81a903d7 R14: ffff88807c978000 R15: ffff88807c978190
FS: 0000000000000000(0000) GS:ffff888125ec2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056115fbc0000 CR3: 000000001daac000 CR4: 00000000003526f0
Call Trace:
rcu_do_batch kernel/rcu/tree.c:2605 [inline]
rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861
handle_softirqs+0x286/0x870 kernel/softirq.c:626
__do_softirq kernel/softirq.c:660 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:727
irq_exit_rcu+0x9/0x30 kernel/softirq.c:743
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
RIP: 0010:rcu_is_watching+0x3a/0xb0 kernel/rcu/tree.c:751
Code: e8 9b e4 b4 09 89 c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd d0 7d 9a 8d 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 6c d6 80 00 48 c7 c3 98 13 77 92 49 03 1e 48 89
RSP: 0000:ffffc90019e0ed38 EFLAGS: 00000246
RAX: 1ffffffff1b34fba RBX: 0000000000000000 RCX: cf3ce818d7638b00
RDX: 0000000000000001 RSI: ffffffff8bbf41c0 RDI: ffffffff8bbf4180
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff81740fc5
R10: ffffc90019e0ee78 R11: ffffffff81ad7830 R12: 1ffff920033c1dc5
R13: ffffc90019e0ee60 R14: ffffffff8d9a7dd0 R15: dffffc0000000000
rcu_read_lock include/linux/rcupdate.h:868 [inline]
class_rcu_constructor include/linux/rcupdate.h:1195 [inline]
unwind_next_frame+0xd4/0x2390 arch/x86/kernel/unwind_orc.c:479
arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
save_stack+0xf5/0x1f0 mm/page_owner.c:165
__reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1395 [inline]
free_unref_folios+0xd22/0x1460 mm/page_alloc.c:3005
folios_put_refs+0x584/0x670 mm/swap.c:1002
folio_batch_release include/linux/pagevec.h:101 [inline]
shmem_undo_range+0x49e/0x1490 mm/shmem.c:1149
shmem_truncate_range mm/shmem.c:1261 [inline]
shmem_evict_inode+0x272/0xa70 mm/shmem.c:1389
evict+0x5f4/0xae0 fs/inode.c:837
__dentry_kill+0x209/0x660 fs/dcache.c:669
dput+0x19f/0x2b0 fs/dcache.c:911
__fput+0x68e/0xa70 fs/file_table.c:476
task_work_run+0x1d4/0x260 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x6bd/0x2300 kernel/exit.c:970
do_group_exit+0x21c/0x2d0 kernel/exit.c:1111
get_signal+0x1285/0x1340 kernel/signal.c:3034
arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop+0x87/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2e9/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f60b2f8f6c9
Code: Unable to access opcode bytes at 0x7f60b2f8f69f.
RSP: 002b:00007f60b3d6efe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: fffffffffffffffc RBX: 00007f60b31e6270 RCX: 00007f60b2f8f6c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000f5982400
RBP: 00007f60b3011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f60b31e6308 R14: 00007f60b31e6270 R15: 00007ffcaca6d7d8
----------------
Code disassembly (best guess):
0: e8 9b e4 b4 09 call 0x9b4e4a0
5: 89 c3 mov %eax,%ebx
7: 83 f8 08 cmp $0x8,%eax
a: 73 65 jae 0x71
c: 49 bf 00 00 00 00 00 movabs $0xdffffc0000000000,%r15
13: fc ff df
16: 4c 8d 34 dd d0 7d 9a lea -0x72658230(,%rbx,8),%r14
1d: 8d
1e: 4c 89 f0 mov %r14,%rax
21: 48 c1 e8 03 shr $0x3,%rax
25: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1)
* 2a: 74 08 je 0x34 <-- trapping instruction
2c: 4c 89 f7 mov %r14,%rdi
2f: e8 6c d6 80 00 call 0x80d6a0
34: 48 c7 c3 98 13 77 92 mov $0xffffffff92771398,%rbx
3b: 49 03 1e add (%r14),%rbx
3e: 48 rex.W
3f: 89 .byte 0x89