====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor/6800 is trying to acquire lock: ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:2995 [inline] ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3315 [inline] ffff8880b8f281d8 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3406 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+0xfe/0xd00 kernel/time/timer.c:1080 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:3176 [inline] kvfree_call_rcu+0x4cb/0x870 kernel/rcu/tree.c:3432 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:3796 ip_init+0xa/0x14 net/ipv4/ip_output.c:1771 inet_init+0x2bd/0x3cf net/ipv4/af_inet.c:2033 do_one_initcall+0x214/0x7a0 init/main.c:1310 do_initcall_level+0x137/0x1e4 init/main.c:1383 do_initcalls+0x4b/0x8a init/main.c:1399 kernel_init_freeable+0x3fa/0x5ac init/main.c:1638 kernel_init+0x19/0x1b0 init/main.c:1526 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:2995 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3315 [inline] kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3406 trie_delete_elem+0x52d/0x690 kernel/bpf/lpm_trie.c:545 bpf_prog_41385012b43a9f2e+0x40/0x44 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_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+0x911/0xd00 kernel/time/timer.c:1131 dsp_cmx_send+0x1ab4/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1850 call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1700 expire_timers kernel/time/timer.c:1751 [inline] __run_timers+0x529/0x7d0 kernel/time/timer.c:2022 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2035 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596 __do_softirq kernel/softirq.c:630 [inline] invoke_softirq kernel/softirq.c:470 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691 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 arch_atomic_read arch/x86/include/asm/atomic.h:29 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:28 [inline] page_table_check_set+0x253/0x6d0 mm/page_table_check.c:127 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+0xde3/0x15c0 kernel/fork.c:1590 copy_process+0x1953/0x4020 kernel/fork.c:2351 kernel_clone+0x225/0x8b0 kernel/fork.c:2757 __do_sys_clone kernel/fork.c:2898 [inline] __se_sys_clone kernel/fork.c:2882 [inline] __x64_sys_clone+0x17c/0x1d0 kernel/fork.c:2882 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 *** 10 locks held by syz-executor/6800: #0: ffffffff8cbc5010 (dup_mmap_sem){++++}-{0:0}, at: dup_mmap kernel/fork.c:593 [inline] #0: ffffffff8cbc5010 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1541 [inline] #0: ffffffff8cbc5010 (dup_mmap_sem){++++}-{0:0}, at: copy_mm+0x2a9/0x15c0 kernel/fork.c:1590 #1: ffff88802f9a5b58 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline] #1: ffff88802f9a5b58 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:594 [inline] #1: ffff88802f9a5b58 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1541 [inline] #1: ffff88802f9a5b58 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x2c3/0x15c0 kernel/fork.c:1590 #2: ffff88807918c4d8 (&mm->mmap_lock/1){+.+.}-{3:3}, at: mmap_write_lock_nested include/linux/mmap_lock.h:78 [inline] #2: ffff88807918c4d8 (&mm->mmap_lock/1){+.+.}-{3:3}, at: dup_mmap kernel/fork.c:603 [inline] #2: ffff88807918c4d8 (&mm->mmap_lock/1){+.+.}-{3:3}, at: dup_mm kernel/fork.c:1541 [inline] #2: ffff88807918c4d8 (&mm->mmap_lock/1){+.+.}-{3:3}, at: copy_mm+0x3ad/0x15c0 kernel/fork.c:1590 #3: ffff88807e6d7498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff88807e6d7498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_pte_range mm/memory.c:1042 [inline] #3: ffff88807e6d7498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_pmd_range mm/memory.c:1177 [inline] #3: ffff88807e6d7498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_pud_range mm/memory.c:1214 [inline] #3: ffff88807e6d7498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_p4d_range mm/memory.c:1238 [inline] #3: ffff88807e6d7498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: copy_page_range+0x1041/0x39e0 mm/memory.c:1336 #4: ffff88807dd82a98 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_pte_range mm/memory.c:1049 [inline] #4: ffff88807dd82a98 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_pmd_range mm/memory.c:1177 [inline] #4: ffff88807dd82a98 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_pud_range mm/memory.c:1214 [inline] #4: ffff88807dd82a98 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_p4d_range mm/memory.c:1238 [inline] #4: ffff88807dd82a98 (ptlock_ptr(page)#2/1){+.+.}-{2:2}, at: copy_page_range+0x1124/0x39e0 mm/memory.c:1336 #5: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #5: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #5: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: page_ext_get+0x1e/0x2a0 mm/page_ext.c:157 #6: ffffc900001e0bc0 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xc1/0x670 kernel/time/timer.c:1697 #7: ffffffff8dac9718 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x22/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1643 #8: ffff8880b8f28418 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999 #9: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #9: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #9: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #9: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0xf0/0x400 kernel/trace/bpf_trace.c:2325 stack backtrace: CPU: 1 PID: 6800 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 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:2995 [inline] add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3315 [inline] kvfree_call_rcu+0x184/0x870 kernel/rcu/tree.c:3406 trie_delete_elem+0x52d/0x690 kernel/bpf/lpm_trie.c:545 bpf_prog_41385012b43a9f2e+0x40/0x44 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_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+0x911/0xd00 kernel/time/timer.c:1131 dsp_cmx_send+0x1ab4/0x1b30 drivers/isdn/mISDN/dsp_cmx.c:1850 call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1700 expire_timers kernel/time/timer.c:1751 [inline] __run_timers+0x529/0x7d0 kernel/time/timer.c:2022 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2035 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596 __do_softirq kernel/softirq.c:630 [inline] invoke_softirq kernel/softirq.c:470 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691 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:page_table_check_set+0x253/0x6d0 mm/page_table_check.c:127 Code: 04 00 00 00 e8 fe ce f5 ff 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 0f 85 00 01 00 00 41 8b 6d 00 <31> ff 89 ee e8 a4 a1 a5 ff 85 ed 0f 85 8d 01 00 00 49 8d 7d 04 be RSP: 0018:ffffc90003e87510 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 1ffffffff1986ca8 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88801b620768 RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed10036c40ee R10: ffffed10036c40ee R11: 1ffff110036c40ed R12: 0000000000000000 R13: ffff88801b620768 R14: 0000000000000000 R15: ffff88801b620728 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+0xde3/0x15c0 kernel/fork.c:1590 copy_process+0x1953/0x4020 kernel/fork.c:2351 kernel_clone+0x225/0x8b0 kernel/fork.c:2757 __do_sys_clone kernel/fork.c:2898 [inline] __se_sys_clone kernel/fork.c:2882 [inline] __x64_sys_clone+0x17c/0x1d0 kernel/fork.c:2882 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: 0033:0x7f5e8af85713 Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffd8ea06528 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5e8af85713 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 000055557fb907d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 000000000005d485 R15: 00007ffd8ea066c0 ---------------- Code disassembly (best guess): 0: 04 00 add $0x0,%al 2: 00 00 add %al,(%rax) 4: e8 fe ce f5 ff call 0xfff5cf07 9: 4c 89 e8 mov %r13,%rax c: 48 c1 e8 03 shr $0x3,%rax 10: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx 17: fc ff df 1a: 0f b6 04 08 movzbl (%rax,%rcx,1),%eax 1e: 84 c0 test %al,%al 20: 0f 85 00 01 00 00 jne 0x126 26: 41 8b 6d 00 mov 0x0(%r13),%ebp * 2a: 31 ff xor %edi,%edi <-- trapping instruction 2c: 89 ee mov %ebp,%esi 2e: e8 a4 a1 a5 ff call 0xffa5a1d7 33: 85 ed test %ebp,%ebp 35: 0f 85 8d 01 00 00 jne 0x1c8 3b: 49 8d 7d 04 lea 0x4(%r13),%rdi 3f: be .byte 0xbe