====================================================== WARNING: possible circular locking dependency detected 5.15.176-syzkaller #0 Not tainted ------------------------------------------------------ syz.0.1525/8493 is trying to acquire lock: ffff8880b8f27e78 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline] ffff8880b8f27e78 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline] ffff8880b8f27e78 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x1b5/0x8a0 kernel/rcu/tree.c:3597 but task is already holding lock: ffff88801762c9b8 (&trie->lock){-...}-{2:2}, at: trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&trie->lock){-...}-{2:2}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __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 bpf_dispatcher_xdp+0x7af/0x1000 bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline] __bpf_prog_run include/linux/filter.h:628 [inline] bpf_prog_run include/linux/filter.h:635 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline] bpf_trace_run2+0x19e/0x340 kernel/trace/bpf_trace.c:1915 trace_hrtimer_start include/trace/events/timer.h:199 [inline] debug_activate kernel/time/hrtimer.c:476 [inline] enqueue_hrtimer+0x324/0x390 kernel/time/hrtimer.c:1084 __hrtimer_start_range_ns kernel/time/hrtimer.c:1259 [inline] hrtimer_start_range_ns+0xabe/0xc80 kernel/time/hrtimer.c:1301 cpu_clock_event_add+0x32/0x40 kernel/events/core.c:10983 event_sched_in+0x721/0xf60 kernel/events/core.c:2654 group_sched_in kernel/events/core.c:2690 [inline] merge_sched_in kernel/events/core.c:3884 [inline] visit_groups_merge+0xe4d/0x2a40 kernel/events/core.c:3828 ctx_flexible_sched_in+0xab/0x100 kernel/events/core.c:3926 ctx_resched+0x248/0x3a0 kernel/events/core.c:2844 __perf_install_in_context+0x59f/0x690 kernel/events/core.c:2912 remote_function+0xe6/0x160 kernel/events/core.c:92 generic_exec_single+0x2b7/0x4d0 kernel/smp.c:518 smp_call_function_single+0x257/0x530 kernel/smp.c:755 task_function_call kernel/events/core.c:120 [inline] perf_install_in_context+0x6b6/0xa90 kernel/events/core.c:3016 __do_sys_perf_event_open kernel/events/core.c:12745 [inline] __se_sys_perf_event_open+0x3608/0x4510 kernel/events/core.c:12339 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #1 (hrtimer_bases.lock){-.-.}-{2:2}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162 lock_hrtimer_base kernel/time/hrtimer.c:173 [inline] hrtimer_start_range_ns+0x105/0xc80 kernel/time/hrtimer.c:1299 hrtimer_start include/linux/hrtimer.h:420 [inline] run_page_cache_worker kernel/rcu/tree.c:3488 [inline] kvfree_call_rcu+0x6a0/0x8a0 kernel/rcu/tree.c:3599 rtnl_register_internal+0x443/0x530 net/core/rtnetlink.c:223 rtnl_register+0x32/0x70 net/core/rtnetlink.c:273 ip_rt_init+0x2e6/0x390 net/ipv4/route.c:3750 ip_init+0xa/0x20 net/ipv4/ip_output.c:1749 inet_init+0x27c/0x390 net/ipv4/af_inet.c:2007 do_one_initcall+0x22b/0x7a0 init/main.c:1302 do_initcall_level+0x157/0x210 init/main.c:1375 do_initcalls+0x49/0x90 init/main.c:1391 kernel_init_freeable+0x425/0x5c0 init/main.c:1615 kernel_init+0x19/0x290 init/main.c:1506 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #0 (krc.lock){..-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline] kvfree_call_rcu+0x1b5/0x8a0 kernel/rcu/tree.c:3597 trie_delete_elem+0x5c8/0x690 kernel/bpf/lpm_trie.c:525 map_delete_elem+0x431/0x580 kernel/bpf/syscall.c:1239 __sys_bpf+0x311/0x670 kernel/bpf/syscall.c:4647 __do_sys_bpf kernel/bpf/syscall.c:4760 [inline] __se_sys_bpf kernel/bpf/syscall.c:4758 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4758 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 other info that might help us debug this: Chain exists of: krc.lock --> hrtimer_bases.lock --> &trie->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&trie->lock); lock(hrtimer_bases.lock); lock(&trie->lock); lock(krc.lock); *** DEADLOCK *** 2 locks held by syz.0.1525/8493: #0: ffffffff8cb1fce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #1: ffff88801762c9b8 (&trie->lock){-...}-{2:2}, at: trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467 stack backtrace: CPU: 1 PID: 8493 Comm: syz.0.1525 Not tainted 5.15.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106 check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133 check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline] kvfree_call_rcu+0x1b5/0x8a0 kernel/rcu/tree.c:3597 trie_delete_elem+0x5c8/0x690 kernel/bpf/lpm_trie.c:525 map_delete_elem+0x431/0x580 kernel/bpf/syscall.c:1239 __sys_bpf+0x311/0x670 kernel/bpf/syscall.c:4647 __do_sys_bpf kernel/bpf/syscall.c:4760 [inline] __se_sys_bpf kernel/bpf/syscall.c:4758 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4758 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fee4bcb6d29 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:00007fee49b27038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fee4bea6fa0 RCX: 00007fee4bcb6d29 RDX: 0000000000000020 RSI: 0000000020000340 RDI: 0000000000000003 RBP: 00007fee4bd32b08 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fee4bea6fa0 R15: 00007ffffebe9468