====================================================== WARNING: possible circular locking dependency detected 6.1.138-syzkaller #0 Not tainted ------------------------------------------------------ syz.2.178/4836 is trying to acquire lock: ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2991 [inline] ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3311 [inline] ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3402 but task is already holding lock: ffff8880b8f28418 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #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:999 __mod_timer+0x117/0xd20 kernel/time/timer.c:1072 queue_delayed_work_on+0x126/0x1e0 kernel/workqueue.c:1704 queue_delayed_work include/linux/workqueue.h:527 [inline] schedule_delayed_monitor_work kernel/rcu/tree.c:3172 [inline] kvfree_call_rcu+0x4cb/0x870 kernel/rcu/tree.c:3428 rtnl_register_internal+0x489/0x590 net/core/rtnetlink.c:260 rtnl_register+0x2e/0x70 net/core/rtnetlink.c:310 ip_rt_init+0x323/0x3b5 net/ipv4/route.c:3789 ip_init+0xa/0x14 net/ipv4/ip_output.c:1770 inet_init+0x2bd/0x3cf net/ipv4/af_inet.c:2033 do_one_initcall+0x214/0x7a0 init/main.c:1298 do_initcall_level+0x137/0x1e4 init/main.c:1371 do_initcalls+0x4b/0x8a init/main.c:1387 kernel_init_freeable+0x3fa/0x5ac init/main.c:1626 kernel_init+0x19/0x1b0 init/main.c:1514 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 -> #0 (krc.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+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 krc_this_cpu_lock kernel/rcu/tree.c:2991 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3311 [inline] kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3402 trie_delete_elem+0x52d/0x690 kernel/bpf/lpm_trie.c:545 bpf_prog_1db1603a7cfa36fb+0x3d/0x41 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [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_run3+0x1e3/0x400 kernel/trace/bpf_trace.c:2325 trace_timer_start include/trace/events/timer.h:53 [inline] enqueue_timer+0x411/0x5c0 kernel/time/timer.c:609 internal_add_timer kernel/time/timer.c:634 [inline] __mod_timer+0x8e1/0xd20 kernel/time/timer.c:1115 call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504 expire_timers kernel/time/timer.c:1549 [inline] __run_timers+0x525/0x7c0 kernel/time/timer.c:1820 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833 handle_softirqs+0x2a1/0x920 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:661 irq_exit_rcu+0x5/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666 rcu_lock_acquire include/linux/rcupdate.h:350 [inline] rcu_read_lock include/linux/rcupdate.h:791 [inline] page_ext_get+0x3a/0x2a0 mm/page_ext.c:157 page_table_check_set+0x51/0x6d0 mm/page_table_check.c:112 page_table_check_pte_set include/linux/page_table_check.h:83 [inline] set_pte_at arch/x86/include/asm/pgtable.h:1009 [inline] copy_present_pte mm/memory.c:1000 [inline] copy_pte_range mm/memory.c:1091 [inline] copy_pmd_range mm/memory.c:1177 [inline] copy_pud_range mm/memory.c:1214 [inline] copy_p4d_range mm/memory.c:1238 [inline] copy_page_range+0x26b3/0x39e0 mm/memory.c:1336 dup_mmap kernel/fork.c:697 [inline] dup_mm kernel/fork.c:1541 [inline] copy_mm+0xde1/0x15c0 kernel/fork.c:1590 copy_process+0x1947/0x4060 kernel/fork.c:2266 kernel_clone+0x225/0x8b0 kernel/fork.c:2681 __do_sys_clone kernel/fork.c:2822 [inline] __se_sys_clone kernel/fork.c:2806 [inline] __x64_sys_clone+0x17c/0x1d0 kernel/fork.c:2806 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 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&base->lock); lock(krc.lock); lock(&base->lock); lock(krc.lock); *** DEADLOCK *** 9 locks held by syz.2.178/4836: #0: ffffffff8c9c6a70 (dup_mmap_sem){++++}-{0:0}, at: dup_mmap kernel/fork.c:593 [inline] #0: ffffffff8c9c6a70 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1541 [inline] #0: ffffffff8c9c6a70 (dup_mmap_sem){++++}-{0:0}, at: copy_mm+0x2a9/0x15c0 kernel/fork.c:1590 #1: ffff88801746a6d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline] #1: ffff88801746a6d8 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:594 [inline] #1: ffff88801746a6d8 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1541 [inline] #1: ffff88801746a6d8 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x2c3/0x15c0 kernel/fork.c:1590 #2: ffff888017469058 (&mm->mmap_lock/1){+.+.}-{3:3}, at: mmap_write_lock_nested include/linux/mmap_lock.h:78 [inline] #2: ffff888017469058 (&mm->mmap_lock/1){+.+.}-{3:3}, at: dup_mmap kernel/fork.c:603 [inline] #2: ffff888017469058 (&mm->mmap_lock/1){+.+.}-{3:3}, at: dup_mm kernel/fork.c:1541 [inline] #2: ffff888017469058 (&mm->mmap_lock/1){+.+.}-{3:3}, at: copy_mm+0x3ad/0x15c0 kernel/fork.c:1590 #3: ffff88807c9633d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff88807c9633d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_pte_range mm/memory.c:1042 [inline] #3: ffff88807c9633d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_pmd_range mm/memory.c:1177 [inline] #3: ffff88807c9633d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_pud_range mm/memory.c:1214 [inline] #3: ffff88807c9633d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_p4d_range mm/memory.c:1238 [inline] #3: ffff88807c9633d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_page_range+0x1041/0x39e0 mm/memory.c:1336 #4: ffff88807aba1798 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_pte_range mm/memory.c:1049 [inline] #4: ffff88807aba1798 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_pmd_range mm/memory.c:1177 [inline] #4: ffff88807aba1798 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_pud_range mm/memory.c:1214 [inline] #4: ffff88807aba1798 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_p4d_range mm/memory.c:1238 [inline] #4: ffff88807aba1798 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_page_range+0x1124/0x39e0 mm/memory.c:1336 #5: ffffffff8c92a960 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #5: ffffffff8c92a960 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #5: ffffffff8c92a960 (rcu_read_lock){....}-{1:2}, at: page_ext_get+0x1e/0x2a0 mm/page_ext.c:157 #6: ffffc900001e0bc0 ((&app->join_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc1/0x670 kernel/time/timer.c:1501 #7: ffff8880b8f28418 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999 #8: ffffffff8c92a960 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #8: ffffffff8c92a960 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #8: ffffffff8c92a960 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #8: ffffffff8c92a960 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf0/0x400 kernel/trace/bpf_trace.c:2325 stack backtrace: CPU: 1 PID: 4836 Comm: syz.2.178 Not tainted 6.1.138-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 Call Trace: dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 check_noncircular+0x274/0x310 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+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 krc_this_cpu_lock kernel/rcu/tree.c:2991 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3311 [inline] kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3402 trie_delete_elem+0x52d/0x690 kernel/bpf/lpm_trie.c:545 bpf_prog_1db1603a7cfa36fb+0x3d/0x41 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [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_run3+0x1e3/0x400 kernel/trace/bpf_trace.c:2325 trace_timer_start include/trace/events/timer.h:53 [inline] enqueue_timer+0x411/0x5c0 kernel/time/timer.c:609 internal_add_timer kernel/time/timer.c:634 [inline] __mod_timer+0x8e1/0xd20 kernel/time/timer.c:1115 call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504 expire_timers kernel/time/timer.c:1549 [inline] __run_timers+0x525/0x7c0 kernel/time/timer.c:1820 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833 handle_softirqs+0x2a1/0x920 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:661 irq_exit_rcu+0x5/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666 Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b RSP: 0018:ffffc9000467f3a0 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 816165f87b0a0600 RDX: 0000000000000000 RSI: ffffffff8a6c0f80 RDI: ffffffff8abf0da0 RBP: ffffc9000467f4c0 R08: dffffc0000000000 R09: fffffbfff2117049 R10: fffffbfff2117049 R11: 1ffffffff2117048 R12: 0000000000000001 R13: 1ffff920008cfe80 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire include/linux/rcupdate.h:350 [inline] rcu_read_lock include/linux/rcupdate.h:791 [inline] page_ext_get+0x3a/0x2a0 mm/page_ext.c:157 page_table_check_set+0x51/0x6d0 mm/page_table_check.c:112 page_table_check_pte_set include/linux/page_table_check.h:83 [inline] set_pte_at arch/x86/include/asm/pgtable.h:1009 [inline] copy_present_pte mm/memory.c:1000 [inline] copy_pte_range mm/memory.c:1091 [inline] copy_pmd_range mm/memory.c:1177 [inline] copy_pud_range mm/memory.c:1214 [inline] copy_p4d_range mm/memory.c:1238 [inline] copy_page_range+0x26b3/0x39e0 mm/memory.c:1336 dup_mmap kernel/fork.c:697 [inline] dup_mm kernel/fork.c:1541 [inline] copy_mm+0xde1/0x15c0 kernel/fork.c:1590 copy_process+0x1947/0x4060 kernel/fork.c:2266 kernel_clone+0x225/0x8b0 kernel/fork.c:2681 __do_sys_clone kernel/fork.c:2822 [inline] __se_sys_clone kernel/fork.c:2806 [inline] __x64_sys_clone+0x17c/0x1d0 kernel/fork.c:2806 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: 0033:0x7fa28ed8e969 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:00007fa28fb7dfe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fa28efb5fa0 RCX: 00007fa28ed8e969 RDX: 0000000000000000 RSI: 0000200000000080 RDI: 0000000020000000 RBP: 00007fa28ee10ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fa28efb5fa0 R15: 00007ffe7cdc8df8 ---------------- Code disassembly (best guess): 0: 00 9c 8f 84 24 80 00 add %bl,0x802484(%rdi,%rcx,4) 7: 00 00 add %al,(%rax) 9: f6 84 24 81 00 00 00 testb $0x2,0x81(%rsp) 10: 02 11: 0f 85 f5 00 00 00 jne 0x10c 17: 41 f7 c6 00 02 00 00 test $0x200,%r14d 1e: 74 01 je 0x21 20: fb sti 21: 48 c7 44 24 60 0e 36 movq $0x45e0360e,0x60(%rsp) 28: e0 45 * 2a: 4b c7 44 3d 00 00 00 movq $0x0,0x0(%r13,%r15,1) <-- trapping instruction 31: 00 00 33: 66 43 c7 44 3d 09 00 movw $0x0,0x9(%r13,%r15,1) 3a: 00 3b: 43 rex.XB 3c: c6 .byte 0xc6 3d: 44 rex.R 3e: 3d .byte 0x3d 3f: 0b .byte 0xb