syzbot

======================================================
WARNING: possible circular locking dependency detected
6.6.101-syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1617/12089 is trying to acquire lock:
ffffffff9707c1a0 (&obj_hash[i].lock){-.-.}-{2:2}, at: __debug_check_no_obj_freed lib/debugobjects.c:979 [inline]
ffffffff9707c1a0 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_check_no_obj_freed+0x13a/0x540 lib/debugobjects.c:1020

but task is already holding lock:
ffff888026272238 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xca/0xea0 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+0xa8/0xf0 kernel/locking/spinlock.c:162
       trie_delete_elem+0x96/0x6a0 kernel/bpf/lpm_trie.c:467
       bpf_prog_2c29ac5cdc6b1842+0x45/0x46
       bpf_dispatcher_nop_func include/linux/bpf.h:1213 [inline]
       __bpf_prog_run include/linux/filter.h:605 [inline]
       bpf_prog_run include/linux/filter.h:619 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
       bpf_trace_run2+0x312/0x3c0 kernel/trace/bpf_trace.c:2361
       __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122
       trace_contention_end+0xe6/0x110 include/trace/events/lock.h:122
       __pv_queued_spin_lock_slowpath+0x7ec/0x9d0 kernel/locking/qspinlock.c:560
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
       queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
       _raw_spin_lock_irqsave+0xb4/0xf0 kernel/locking/spinlock.c:162
       debug_object_deactivate+0x67/0x350 lib/debugobjects.c:764
       debug_hrtimer_deactivate kernel/time/hrtimer.c:455 [inline]
       debug_deactivate+0x1d/0x1d0 kernel/time/hrtimer.c:511
       __run_hrtimer kernel/time/hrtimer.c:1723 [inline]
       __hrtimer_run_queues+0x2bf/0xc40 kernel/time/hrtimer.c:1819
       hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1881
       local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
       __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
       sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
       asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
       orc_find arch/x86/kernel/unwind_orc.c:211 [inline]
       unwind_next_frame+0x217/0x2970 arch/x86/kernel/unwind_orc.c:494
       __unwind_start+0x66a/0x7e0 arch/x86/kernel/unwind_orc.c:760
       unwind_start arch/x86/include/asm/unwind.h:64 [inline]
       arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24
       stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
       kasan_save_stack mm/kasan/common.c:45 [inline]
       kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
       ____kasan_kmalloc mm/kasan/common.c:374 [inline]
       __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
       kasan_kmalloc include/linux/kasan.h:198 [inline]
       __do_kmalloc_node mm/slab_common.c:1007 [inline]
       __kmalloc_node_track_caller+0xb2/0x230 mm/slab_common.c:1027
       __do_krealloc mm/slab_common.c:1402 [inline]
       krealloc+0x86/0x120 mm/slab_common.c:1435
       push_jmp_history kernel/bpf/verifier.c:3443 [inline]
       do_check+0x4b89/0xdbe0 kernel/bpf/verifier.c:17098
       do_check_common+0xadb/0x13e0 kernel/bpf/verifier.c:19699
       do_check_main kernel/bpf/verifier.c:19762 [inline]
       bpf_check+0x649f/0xe970 kernel/bpf/verifier.c:20430
       bpf_prog_load+0x11cb/0x16d0 kernel/bpf/syscall.c:2744
       __sys_bpf+0x55a/0x800 kernel/bpf/syscall.c:5467
       __do_sys_bpf kernel/bpf/syscall.c:5571 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5569 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5569
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&obj_hash[i].lock){-.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
       __debug_check_no_obj_freed lib/debugobjects.c:979 [inline]
       debug_check_no_obj_freed+0x13a/0x540 lib/debugobjects.c:1020
       slab_free_hook mm/slub.c:1781 [inline]
       slab_free_freelist_hook+0xd2/0x1b0 mm/slub.c:1832
       slab_free mm/slub.c:3816 [inline]
       __kmem_cache_free+0xba/0x1f0 mm/slub.c:3829
       trie_update_elem+0x6d1/0xea0 kernel/bpf/lpm_trie.c:444
       bpf_map_update_value+0x660/0x720 kernel/bpf/syscall.c:201
       generic_map_update_batch+0x5e0/0x810 kernel/bpf/syscall.c:1794
       bpf_map_do_batch+0x3d7/0x610 kernel/bpf/syscall.c:5001
       __sys_bpf+0x31b/0x800 kernel/bpf/syscall.c:-1
       __do_sys_bpf kernel/bpf/syscall.c:5571 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5569 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5569
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 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(&obj_hash[i].lock);
                               lock(&trie->lock);
  lock(&obj_hash[i].lock);

 *** DEADLOCK ***

2 locks held by syz.2.1617/12089:
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x41d/0x720 kernel/bpf/syscall.c:200
 #1: ffff888026272238 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xca/0xea0 kernel/bpf/lpm_trie.c:335

stack backtrace:
CPU: 1 PID: 12089 Comm: syz.2.1617 Not tainted 6.6.101-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
 __debug_check_no_obj_freed lib/debugobjects.c:979 [inline]
 debug_check_no_obj_freed+0x13a/0x540 lib/debugobjects.c:1020
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook+0xd2/0x1b0 mm/slub.c:1832
 slab_free mm/slub.c:3816 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3829
 trie_update_elem+0x6d1/0xea0 kernel/bpf/lpm_trie.c:444
 bpf_map_update_value+0x660/0x720 kernel/bpf/syscall.c:201
 generic_map_update_batch+0x5e0/0x810 kernel/bpf/syscall.c:1794
 bpf_map_do_batch+0x3d7/0x610 kernel/bpf/syscall.c:5001
 __sys_bpf+0x31b/0x800 kernel/bpf/syscall.c:-1
 __do_sys_bpf kernel/bpf/syscall.c:5571 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5569 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5569
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fee85d8ebe9
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:00007fee86c4c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fee85fb5fa0 RCX: 00007fee85d8ebe9
RDX: 0000000000000038 RSI: 0000200000000240 RDI: 000000000000001a
RBP: 00007fee85e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fee85fb6038 R14: 00007fee85fb5fa0 R15: 00007ffd0db9bba8
 </TASK>