syzbot

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.4.171/4651 is trying to acquire lock:
ffff888027bb7238 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467

but task is already holding lock:
ffff888027bb7a38 (&trie->lock){..-.}-{2:2}, at: trie_update_elem+0xc4/0xe90 kernel/bpf/lpm_trie.c:335

other info that might help us debug this:
 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz.4.171/4651:
 #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x375/0x670 kernel/bpf/syscall.c:227
 #1: ffff888027bb7a38 (&trie->lock){..-.}-{2:2}, at: trie_update_elem+0xc4/0xe90 kernel/bpf/lpm_trie.c:335
 #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
 #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run4+0xf9/0x420 kernel/trace/bpf_trace.c:2326

stack backtrace:
CPU: 1 PID: 4651 Comm: syz.4.171 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 __lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
 trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467
 bpf_prog_8c8ab8634bca3061+0x3a/0x44
 bpf_dispatcher_nop_func include/linux/bpf.h:1012 [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:2285 [inline]
 bpf_trace_run4+0x1f5/0x420 kernel/trace/bpf_trace.c:2326
 __bpf_trace_mm_page_alloc+0xbf/0xf0 include/trace/events/kmem.h:177
 trace_mm_page_alloc include/trace/events/kmem.h:177 [inline]
 __alloc_pages+0x49c/0x4e0 mm/page_alloc.c:5636
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_pages_node include/linux/gfp.h:260 [inline]
 __kmalloc_large_node+0x8c/0x1e0 mm/slab_common.c:1077
 __do_kmalloc_node mm/slab_common.c:924 [inline]
 __kmalloc_node+0x10e/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+0x160/0xe90 kernel/bpf/lpm_trie.c:338
 bpf_map_update_value+0x59e/0x670 kernel/bpf/syscall.c:228
 map_update_elem+0x4d7/0x680 kernel/bpf/syscall.c:1473
 __sys_bpf+0x454/0x6d0 kernel/bpf/syscall.c:5015
 __do_sys_bpf kernel/bpf/syscall.c:5131 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5129 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fda6bb8f6c9
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:00007ffebd8d3978 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fda6bde5fa0 RCX: 00007fda6bb8f6c9
RDX: 0000000000000020 RSI: 0000200000000000 RDI: 0000000000000002
RBP: 00007fda6bc11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fda6bde5fa0 R14: 00007fda6bde5fa0 R15: 0000000000000003
 </TASK>