====================================================== WARNING: possible circular locking dependency detected 5.15.189-syzkaller #0 Not tainted ------------------------------------------------------ syz.2.50/4399 is trying to acquire lock: ffff8880b9127e78 (krc.lock){....}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3203 [inline] ffff8880b9127e78 (krc.lock){....}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline] ffff8880b9127e78 (krc.lock){....}-{2:2}, at: kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3601 but task is already holding lock: ffff8880792dcdb8 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x90/0x710 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}: __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+0x90/0x710 kernel/bpf/lpm_trie.c:467 0xffffffffa00284f5 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_run3+0x17e/0x320 kernel/trace/bpf_trace.c:1916 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x394/0x520 kernel/time/timer.c:586 internal_add_timer kernel/time/timer.c:611 [inline] __mod_timer+0x8e1/0xd20 kernel/time/timer.c:1062 sk_reset_timer+0x1f/0xb0 net/core/sock.c:3137 tipc_sk_finish_conn+0x154/0x7e0 net/tipc/socket.c:1675 tipc_socketpair+0x250/0x470 net/tipc/socket.c:3348 __sys_socketpair+0x2ac/0x540 net/socket.c:1659 __do_sys_socketpair net/socket.c:1695 [inline] __se_sys_socketpair net/socket.c:1692 [inline] __x64_sys_socketpair+0x97/0xb0 net/socket.c:1692 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #1 (&base->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 lock_timer_base+0x123/0x270 kernel/time/timer.c:946 __mod_timer+0x117/0xd20 kernel/time/timer.c:1019 queue_delayed_work_on+0x126/0x1e0 kernel/workqueue.c:1715 queue_delayed_work include/linux/workqueue.h:527 [inline] schedule_delayed_work include/linux/workqueue.h:631 [inline] kvfree_call_rcu+0x4a9/0x7c0 kernel/rcu/tree.c:3629 rtnl_register_internal+0x44e/0x540 net/core/rtnetlink.c:223 rtnl_register+0x2e/0x70 net/core/rtnetlink.c:273 ip_rt_init+0x2e0/0x3a0 net/ipv4/route.c:3795 ip_init+0xa/0x20 net/ipv4/ip_output.c:1749 inet_init+0x28b/0x3a0 net/ipv4/af_inet.c:2007 do_one_initcall+0x1ee/0x680 init/main.c:1302 do_initcall_level+0x137/0x1f0 init/main.c:1375 do_initcalls+0x4b/0x90 init/main.c:1391 kernel_init_freeable+0x3ce/0x560 init/main.c:1615 kernel_init+0x19/0x1b0 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 kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 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:3203 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline] kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3601 trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1 bpf_prog_8c8ab8634bca3061+0x3a/0x230 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_run3+0x17e/0x320 kernel/trace/bpf_trace.c:1916 __bpf_trace_kmem_cache_free+0x99/0xc0 include/trace/events/kmem.h:138 trace_kmem_cache_free include/trace/events/kmem.h:138 [inline] kmem_cache_free+0x1e7/0x210 mm/slub.c:3516 jbd2_free_handle include/linux/jbd2.h:1602 [inline] jbd2_journal_stop+0x8c2/0xd20 fs/jbd2/transaction.c:1965 __ext4_journal_stop+0xf2/0x190 fs/ext4/ext4_jbd2.c:127 __mark_inode_dirty+0x2b0/0xc60 fs/fs-writeback.c:2464 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x38b/0x400 fs/inode.c:2083 ext4_page_mkwrite+0x1b4/0x1240 fs/ext4/inode.c:6158 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922 do_shared_fault mm/memory.c:4328 [inline] do_fault mm/memory.c:4396 [inline] handle_pte_fault mm/memory.c:4650 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1d4b/0x43c0 mm/memory.c:4883 do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1445 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 other info that might help us debug this: Chain exists of: krc.lock --> &base->lock --> &trie->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&trie->lock); lock(&base->lock); lock(&trie->lock); lock(krc.lock); *** DEADLOCK *** 4 locks held by syz.2.50/4399: #0: ffff88807b36a428 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline] #0: ffff88807b36a428 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2b9/0xc80 arch/x86/mm/fault.c:1298 #1: ffff88814cbf6558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline] #1: ffff88814cbf6558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline] #1: ffff88814cbf6558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x19d/0x1240 fs/ext4/inode.c:6157 #2: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #3: ffff8880792dcdb8 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 stack backtrace: CPU: 1 PID: 4399 Comm: syz.2.50 Not tainted 5.15.189-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 check_noncircular+0x274/0x310 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 kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 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:3203 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline] kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3601 trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1 bpf_prog_8c8ab8634bca3061+0x3a/0x230 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_run3+0x17e/0x320 kernel/trace/bpf_trace.c:1916 __bpf_trace_kmem_cache_free+0x99/0xc0 include/trace/events/kmem.h:138 trace_kmem_cache_free include/trace/events/kmem.h:138 [inline] kmem_cache_free+0x1e7/0x210 mm/slub.c:3516 jbd2_free_handle include/linux/jbd2.h:1602 [inline] jbd2_journal_stop+0x8c2/0xd20 fs/jbd2/transaction.c:1965 __ext4_journal_stop+0xf2/0x190 fs/ext4/ext4_jbd2.c:127 __mark_inode_dirty+0x2b0/0xc60 fs/fs-writeback.c:2464 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x38b/0x400 fs/inode.c:2083 ext4_page_mkwrite+0x1b4/0x1240 fs/ext4/inode.c:6158 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922 do_shared_fault mm/memory.c:4328 [inline] do_fault mm/memory.c:4396 [inline] handle_pte_fault mm/memory.c:4650 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1d4b/0x43c0 mm/memory.c:4883 do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1445 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0033:0x7f85e035bc47 Code: 49 89 ee 41 83 e6 03 0f 85 0e 02 00 00 48 89 df be 04 00 00 00 e8 f9 7d fe ff 48 8b 43 38 83 43 28 04 48 8d 50 fc 48 89 53 38 <44> 89 68 fc 8b 43 28 48 83 c4 38 5b 5d 41 5c 41 5d 41 5e 41 5f c3 RSP: 002b:00007ffc1535f970 EFLAGS: 00010202 RAX: 0000001b31420000 RBX: 00007f85e11d2720 RCX: 0000001b31020218 RDX: 0000001b3141fffc RSI: 00000000003ffde8 RDI: 00007f85e11d2700 RBP: 0000000000000000 R08: 00007f85e06a3038 R09: 00007f85e068f000 R10: 00007f85e11d2700 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 00000000000001ba