syzbot

======================================================
WARNING: possible circular locking dependency detected
6.1.131-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.479/6219 is trying to acquire lock:
ffffffff8d9db0c8 (depot_lock){-.-.}-{2:2}, at: __stack_depot_save+0x1bb/0x470 lib/stackdepot.c:479

but task is already holding lock:
ffff888057152238 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xc6/0xdc0 kernel/bpf/lpm_trie.c:335

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&trie->lock){-.-.}-{2:2}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
       trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467
       0xffffffffa0002027
       bpf_dispatcher_nop_func include/linux/bpf.h:1000 [inline]
       __bpf_prog_run include/linux/filter.h:603 [inline]
       bpf_prog_run include/linux/filter.h:610 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
       bpf_trace_run2+0x1fd/0x410 kernel/trace/bpf_trace.c:2323
       trace_contention_end+0x14c/0x190 include/trace/events/lock.h:122
       __pv_queued_spin_lock_slowpath+0x935/0xc50 kernel/locking/qspinlock.c:560
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
       queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x269/0x370 kernel/locking/spinlock_debug.c:115
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
       _raw_spin_lock_irqsave+0xdd/0x120 kernel/locking/spinlock.c:162
       __stack_depot_save+0x1bb/0x470 lib/stackdepot.c:479
       kasan_save_stack mm/kasan/common.c:46 [inline]
       kasan_set_track+0x60/0x70 mm/kasan/common.c:52
       __kasan_slab_alloc+0x65/0x70 mm/kasan/common.c:328
       kasan_slab_alloc include/linux/kasan.h:201 [inline]
       slab_post_alloc_hook+0x52/0x3a0 mm/slab.h:737
       slab_alloc_node mm/slub.c:3398 [inline]
       slab_alloc mm/slub.c:3406 [inline]
       __kmem_cache_alloc_lru mm/slub.c:3413 [inline]
       kmem_cache_alloc+0x10c/0x2d0 mm/slub.c:3422
       kmem_cache_zalloc include/linux/slab.h:689 [inline]
       fill_pool lib/debugobjects.c:169 [inline]
       debug_objects_fill_pool+0x641/0xa10 lib/debugobjects.c:607
       debug_object_activate+0x32/0x4e0 lib/debugobjects.c:694
       debug_rcu_head_queue kernel/rcu/rcu.h:190 [inline]
       call_rcu+0x93/0xa10 kernel/rcu/tree.c:2830
       __destroy_inode+0x2d5/0x640 fs/inode.c:286
       destroy_inode fs/inode.c:309 [inline]
       evict+0x7d6/0x930 fs/inode.c:720
       __dentry_kill+0x436/0x650 fs/dcache.c:611
       shrink_dentry_list+0x3d9/0x700 fs/dcache.c:1206
       shrink_dcache_parent+0xc9/0x4a0
       d_invalidate+0x118/0x2d0 fs/dcache.c:1742
       proc_invalidate_siblings_dcache+0x3f7/0x6e0 fs/proc/inode.c:148
       release_task+0x1553/0x16d0 kernel/exit.c:278
       wait_task_zombie kernel/exit.c:1207 [inline]
       wait_consider_task+0x1a64/0x2e90 kernel/exit.c:1434
       do_wait_thread kernel/exit.c:1497 [inline]
       do_wait+0x32b/0xb80 kernel/exit.c:1614
       kernel_wait4+0x29e/0x3e0 kernel/exit.c:1777
       __do_sys_wait4 kernel/exit.c:1805 [inline]
       __se_sys_wait4 kernel/exit.c:1801 [inline]
       __x64_sys_wait4+0x130/0x1e0 kernel/exit.c:1801
       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

-> #0 (depot_lock){-.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
       __stack_depot_save+0x1bb/0x470 lib/stackdepot.c:479
       kasan_save_stack mm/kasan/common.c:46 [inline]
       kasan_set_track+0x60/0x70 mm/kasan/common.c:52
       ____kasan_kmalloc mm/kasan/common.c:374 [inline]
       __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:383
       kasan_kmalloc include/linux/kasan.h:211 [inline]
       __do_kmalloc_node mm/slab_common.c:936 [inline]
       __kmalloc_node+0xb3/0x230 mm/slab_common.c:943
       kmalloc_node include/linux/slab.h:589 [inline]
       bpf_map_kmalloc_node+0xce/0x1c0 kernel/bpf/syscall.c:452
       lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
       trie_update_elem+0x175/0xdc0 kernel/bpf/lpm_trie.c:338
       bpf_map_update_value+0x5cf/0x6f0 kernel/bpf/syscall.c:226
       map_update_elem+0x503/0x680 kernel/bpf/syscall.c:1463
       __sys_bpf+0x337/0x6c0 kernel/bpf/syscall.c:5005
       __do_sys_bpf kernel/bpf/syscall.c:5121 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5119 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5119
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&trie->lock);
                               lock(depot_lock);
                               lock(&trie->lock);
  lock(depot_lock);

 *** DEADLOCK ***

2 locks held by syz.0.479/6219:
 #0: ffffffff8d32e6c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d32e6c0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d32e6c0 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x207/0x6f0 kernel/bpf/syscall.c:225
 #1: ffff888057152238 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xc6/0xdc0 kernel/bpf/lpm_trie.c:335

stack backtrace:
CPU: 0 PID: 6219 Comm: syz.0.479 Not tainted 6.1.131-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
 __stack_depot_save+0x1bb/0x470 lib/stackdepot.c:479
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x60/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc_node+0xb3/0x230 mm/slab_common.c:943
 kmalloc_node include/linux/slab.h:589 [inline]
 bpf_map_kmalloc_node+0xce/0x1c0 kernel/bpf/syscall.c:452
 lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
 trie_update_elem+0x175/0xdc0 kernel/bpf/lpm_trie.c:338
 bpf_map_update_value+0x5cf/0x6f0 kernel/bpf/syscall.c:226
 map_update_elem+0x503/0x680 kernel/bpf/syscall.c:1463
 __sys_bpf+0x337/0x6c0 kernel/bpf/syscall.c:5005
 __do_sys_bpf kernel/bpf/syscall.c:5121 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5119 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5119
 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: 0033:0x7f830178d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f83015bd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f83019a6160 RCX: 00007f830178d169
RDX: 0000000000000020 RSI: 0000200000000380 RDI: 0000000000000002
RBP: 00007f830180e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f83019a6160 R15: 00007fff2f9d2828
 </TASK>