============================================ WARNING: possible recursive locking detected 6.1.90-syzkaller #0 Not tainted -------------------------------------------- syz-executor.4/5971 is trying to acquire lock: ffffc900063490d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x20d/0x4f0 kernel/bpf/ringbuf.c:410 but task is already holding lock: ffffc900063490d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x20d/0x4f0 kernel/bpf/ringbuf.c:410 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rb->spinlock); lock(&rb->spinlock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor.4/5971: #0: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: bpf_test_timer_enter+0x19/0x140 net/bpf/test_run.c:36 #1: ffffc900063490d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x20d/0x4f0 kernel/bpf/ringbuf.c:410 #2: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #2: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #2: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2272 [inline] #2: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x110/0x410 kernel/trace/bpf_trace.c:2312 stack backtrace: CPU: 0 PID: 5971 Comm: syz-executor.4 Not tainted 6.1.90-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2983 [inline] check_deadlock kernel/locking/lockdep.c:3026 [inline] validate_chain+0x4711/0x5950 kernel/locking/lockdep.c:3812 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x20d/0x4f0 kernel/bpf/ringbuf.c:410 ____bpf_ringbuf_output kernel/bpf/ringbuf.c:520 [inline] bpf_ringbuf_output+0x63/0x1e0 kernel/bpf/ringbuf.c:510 bpf_prog_a3e2825f60354855+0x3d/0x41 bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline] __bpf_prog_run include/linux/filter.h:596 [inline] bpf_prog_run include/linux/filter.h:610 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline] bpf_trace_run2+0x361/0x410 kernel/trace/bpf_trace.c:2312 trace_contention_end+0x14c/0x190 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x935/0xc50 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x269/0x370 kernel/locking/spinlock_debug.c:115 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xdd/0x120 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x20d/0x4f0 kernel/bpf/ringbuf.c:410 ____bpf_ringbuf_output kernel/bpf/ringbuf.c:520 [inline] bpf_ringbuf_output+0x63/0x1e0 kernel/bpf/ringbuf.c:510 bpf_prog_a3e2825f60354855+0x3d/0x41 bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline] __bpf_prog_run include/linux/filter.h:596 [inline] bpf_prog_run include/linux/filter.h:610 [inline] bpf_test_run+0x60c/0x8b0 net/bpf/test_run.c:402 bpf_prog_test_run_skb+0xaf1/0x13a0 net/bpf/test_run.c:1180 bpf_prog_test_run+0x32f/0x3a0 kernel/bpf/syscall.c:3670 __sys_bpf+0x3eb/0x6c0 kernel/bpf/syscall.c:5023 __do_sys_bpf kernel/bpf/syscall.c:5109 [inline] __se_sys_bpf kernel/bpf/syscall.c:5107 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5107 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fe83527dd69 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fe835f500c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fe8353abf80 RCX: 00007fe83527dd69 RDX: 0000000000000050 RSI: 0000000020000000 RDI: 000000000000000a RBP: 00007fe8352ca49e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007fe8353abf80 R15: 00007ffc819da498