====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.5.953/6935 is trying to acquire lock: ffff88807fa6d420 (&htab->lockdep_key#2){....}-{2:2}, at: htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 but task is already holding lock: ffff88807fa6d1a0 (&htab->lockdep_key){..-.}-{2:2}, at: htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&htab->lockdep_key){..-.}-{2:2}: __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 htab_map_delete_elem+0x19e/0x5b0 kernel/bpf/hashtab.c:1402 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e 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_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324 __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122 trace_contention_end+0x13f/0x190 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7e8/0x9c0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115 htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1ad/0x760 kernel/bpf/hashtab.c:1438 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e 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_prog_run_pin_on_cpu include/linux/filter.h:627 [inline] bpf_flow_dissect+0x12c/0x3e0 net/core/flow_dissector.c:922 bpf_prog_test_run_flow_dissector+0x409/0x600 net/bpf/test_run.c:1484 bpf_prog_test_run+0x31e/0x390 kernel/bpf/syscall.c:3692 __sys_bpf+0x593/0x6d0 kernel/bpf/syscall.c:5045 __do_sys_bpf kernel/bpf/syscall.c:5131 [inline] __se_sys_bpf kernel/bpf/syscall.c:5129 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129 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 -> #0 (&htab->lockdep_key#2){....}-{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 htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1ad/0x760 kernel/bpf/hashtab.c:1438 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e 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_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324 __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122 trace_contention_end+0x13f/0x190 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7e8/0x9c0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115 htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 htab_map_delete_elem+0x19e/0x5b0 kernel/bpf/hashtab.c:1402 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e 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_prog_run_pin_on_cpu include/linux/filter.h:627 [inline] bpf_flow_dissect+0x12c/0x3e0 net/core/flow_dissector.c:922 bpf_prog_test_run_flow_dissector+0x409/0x600 net/bpf/test_run.c:1484 bpf_prog_test_run+0x31e/0x390 kernel/bpf/syscall.c:3692 __sys_bpf+0x593/0x6d0 kernel/bpf/syscall.c:5045 __do_sys_bpf kernel/bpf/syscall.c:5131 [inline] __se_sys_bpf kernel/bpf/syscall.c:5129 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129 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(&htab->lockdep_key); lock(&htab->lockdep_key#2); lock(&htab->lockdep_key); lock(&htab->lockdep_key#2); *** DEADLOCK *** 3 locks held by syz.5.953/6935: #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: bpf_test_timer_enter+0x1a/0x140 net/bpf/test_run.c:36 #1: ffff88807fa6d1a0 (&htab->lockdep_key){..-.}-{2:2}, at: htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #2: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xda/0x3b0 kernel/trace/bpf_trace.c:2324 stack backtrace: CPU: 1 PID: 6935 Comm: syz.5.953 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 htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1ad/0x760 kernel/bpf/hashtab.c:1438 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e 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_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324 __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122 trace_contention_end+0x13f/0x190 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7e8/0x9c0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115 htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166 htab_map_delete_elem+0x19e/0x5b0 kernel/bpf/hashtab.c:1402 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e 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_prog_run_pin_on_cpu include/linux/filter.h:627 [inline] bpf_flow_dissect+0x12c/0x3e0 net/core/flow_dissector.c:922 bpf_prog_test_run_flow_dissector+0x409/0x600 net/bpf/test_run.c:1484 bpf_prog_test_run+0x31e/0x390 kernel/bpf/syscall.c:3692 __sys_bpf+0x593/0x6d0 kernel/bpf/syscall.c:5045 __do_sys_bpf kernel/bpf/syscall.c:5131 [inline] __se_sys_bpf kernel/bpf/syscall.c:5129 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129 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: 0033:0x7ff60258f6c9 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:00007ff6034a5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007ff6027e5fa0 RCX: 00007ff60258f6c9 RDX: 0000000000000050 RSI: 0000200000000180 RDI: 000000000000000a RBP: 00007ff602611f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff6027e6038 R14: 00007ff6027e5fa0 R15: 00007fff99e88928