syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.3277/13478 is trying to acquire lock:
ffff888017440d98 (&n->list_lock){-.-.}-{2:2}, at: get_partial_node+0x36/0x470 mm/slub.c:2215

but task is already holding lock:
ffff88804c0eaa38 (&trie->lock){..-.}-{2:2}, at: trie_update_elem+0xc7/0xe80 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}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
       trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467
       0xffffffffa00009da
       bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
       __bpf_prog_run include/linux/filter.h:607 [inline]
       bpf_prog_run include/linux/filter.h:614 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
       bpf_trace_run2+0x1d5/0x3e0 kernel/trace/bpf_trace.c:2324
       trace_contention_end+0x13f/0x190 include/trace/events/lock.h:122
       __pv_queued_spin_lock_slowpath+0x7e8/0x9c0 kernel/locking/qspinlock.c:560
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
       queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
       _raw_spin_lock_irqsave+0xbc/0x100 kernel/locking/spinlock.c:162
       __unfreeze_partials+0x71/0x200 mm/slub.c:2555
       put_cpu_partial+0x17c/0x250 mm/slub.c:2667
       qlink_free mm/kasan/quarantine.c:168 [inline]
       qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
       kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
       __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
       kasan_slab_alloc include/linux/kasan.h:201 [inline]
       slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
       slab_alloc_node mm/slub.c:3359 [inline]
       slab_alloc mm/slub.c:3367 [inline]
       __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
       kmem_cache_alloc+0x123/0x2f0 mm/slub.c:3383
       kmem_cache_zalloc include/linux/slab.h:689 [inline]
       lsm_file_alloc security/security.c:575 [inline]
       security_file_alloc+0x30/0x110 security/security.c:1543
       __alloc_file+0xc2/0x230 fs/file_table.c:143
       alloc_empty_file+0x90/0x180 fs/file_table.c:187
       alloc_file+0x5c/0x5f0 fs/file_table.c:229
       alloc_file_pseudo+0x180/0x200 fs/file_table.c:272
       __anon_inode_getfile fs/anon_inodes.c:122 [inline]
       anon_inode_getfile+0xc1/0x1a0 fs/anon_inodes.c:160
       __do_sys_perf_event_open kernel/events/core.c:12604 [inline]
       __se_sys_perf_event_open+0xc26/0x1ec0 kernel/events/core.c:12378
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&n->list_lock){-.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
       get_partial_node+0x36/0x470 mm/slub.c:2215
       get_partial mm/slub.c:2330 [inline]
       ___slab_alloc+0x968/0x1240 mm/slub.c:3131
       __slab_alloc mm/slub.c:3240 [inline]
       slab_alloc_node mm/slub.c:3325 [inline]
       __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
       __do_kmalloc_node mm/slab_common.c:935 [inline]
       __kmalloc_node+0xa0/0x240 mm/slab_common.c:943
       kmalloc_node include/linux/slab.h:589 [inline]
       bpf_map_kmalloc_node+0xb8/0x1a0 kernel/bpf/syscall.c:454
       lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
       trie_update_elem+0x163/0xe80 kernel/bpf/lpm_trie.c:338
       bpf_map_update_value+0x59e/0x670 kernel/bpf/syscall.c:228
       generic_map_update_batch+0x54b/0x810 kernel/bpf/syscall.c:1709
       bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1
       __sys_bpf+0x6f7/0x780 kernel/bpf/syscall.c:-1
       __do_sys_bpf kernel/bpf/syscall.c:5134 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5132 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5132
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       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(&n->list_lock);
                               lock(&trie->lock);
  lock(&n->list_lock);

 *** DEADLOCK ***

2 locks held by syz.0.3277/13478:
 #0: ffffffff8cb2b2a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2b2a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2b2a0 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x375/0x670 kernel/bpf/syscall.c:227
 #1: ffff88804c0eaa38 (&trie->lock){..-.}-{2:2}, at: trie_update_elem+0xc7/0xe80 kernel/bpf/lpm_trie.c:335

stack backtrace:
CPU: 1 PID: 13478 Comm: syz.0.3277 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 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 kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
 get_partial_node+0x36/0x470 mm/slub.c:2215
 get_partial mm/slub.c:2330 [inline]
 ___slab_alloc+0x968/0x1240 mm/slub.c:3131
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc_node+0xa0/0x240 mm/slab_common.c:943
 kmalloc_node include/linux/slab.h:589 [inline]
 bpf_map_kmalloc_node+0xb8/0x1a0 kernel/bpf/syscall.c:454
 lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
 trie_update_elem+0x163/0xe80 kernel/bpf/lpm_trie.c:338
 bpf_map_update_value+0x59e/0x670 kernel/bpf/syscall.c:228
 generic_map_update_batch+0x54b/0x810 kernel/bpf/syscall.c:1709
 bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1
 __sys_bpf+0x6f7/0x780 kernel/bpf/syscall.c:-1
 __do_sys_bpf kernel/bpf/syscall.c:5134 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5132 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5132
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5d82d9acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5d83bf6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f5d83015fa0 RCX: 00007f5d82d9acb9
RDX: 0000000000000038 RSI: 0000200000000680 RDI: 000000000000001a
RBP: 00007f5d82e08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5d83016038 R14: 00007f5d83015fa0 R15: 00007ffdefd0f0f8
 </TASK>