============================================ WARNING: possible recursive locking detected 6.10.0-syzkaller-12710-g3a7e02c040b1 #0 Not tainted -------------------------------------------- syz.2.1457/10782 is trying to acquire lock: ffffc900094d90d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:427 but task is already holding lock: ffffc900094d90d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:427 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.2.1457/10782: #0: ffffffff8ddb94e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #0: ffffffff8ddb94e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #0: ffffffff8ddb94e0 (rcu_read_lock){....}-{1:2}, at: bpf_test_timer_enter+0x30/0x180 net/bpf/test_run.c:40 #1: ffffc900094d90d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:427 #2: ffffffff8ddb94e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #2: ffffffff8ddb94e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #2: ffffffff8ddb94e0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2405 [inline] #2: ffffffff8ddb94e0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x1c2/0x590 kernel/trace/bpf_trace.c:2447 stack backtrace: CPU: 1 UID: 0 PID: 10782 Comm: syz.2.1457 Not tainted 6.10.0-syzkaller-12710-g3a7e02c040b1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 Call Trace: __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119 check_deadlock kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3855 [inline] __lock_acquire+0x2167/0x3cb0 kernel/locking/lockdep.c:5142 lock_acquire kernel/locking/lockdep.c:5759 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:427 ____bpf_ringbuf_output kernel/bpf/ringbuf.c:553 [inline] bpf_ringbuf_output+0x60/0xd0 kernel/bpf/ringbuf.c:543 bpf_prog_918f90024333f9ff+0x42/0x4a bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline] __bpf_prog_run include/linux/filter.h:691 [inline] bpf_prog_run include/linux/filter.h:698 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2406 [inline] bpf_trace_run2+0x234/0x590 kernel/trace/bpf_trace.c:2447 __bpf_trace_contention_end+0xca/0x110 include/trace/events/lock.h:122 trace_contention_end.constprop.0+0xea/0x170 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x28e/0xcc0 kernel/locking/qspinlock.c:557 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x210/0x2c0 kernel/locking/spinlock_debug.c:116 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0x42/0x60 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x36e/0x4b0 kernel/bpf/ringbuf.c:427 ____bpf_ringbuf_output kernel/bpf/ringbuf.c:553 [inline] bpf_ringbuf_output+0x60/0xd0 kernel/bpf/ringbuf.c:543 bpf_prog_918f90024333f9ff+0x42/0x4a bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline] __bpf_prog_run include/linux/filter.h:691 [inline] bpf_prog_run include/linux/filter.h:698 [inline] bpf_test_run+0x4a0/0xa90 net/bpf/test_run.c:433 bpf_prog_test_run_skb+0xb6e/0x20f0 net/bpf/test_run.c:1094 bpf_prog_test_run kernel/bpf/syscall.c:4313 [inline] __sys_bpf+0x10d5/0x4a30 kernel/bpf/syscall.c:5728 __do_sys_bpf kernel/bpf/syscall.c:5817 [inline] __se_sys_bpf kernel/bpf/syscall.c:5815 [inline] __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5815 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd18fd77299 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:00007fd190be5048 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fd18ff05f80 RCX: 00007fd18fd77299 RDX: 0000000000000050 RSI: 0000000020000000 RDI: 000000000000000a RBP: 00007fd18fde48e6 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007fd18ff05f80 R15: 00007fff2b6a05f8