============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.4.1505/9912 is trying to acquire lock: ffffc9000d9b40d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:413 but task is already holding lock: ffffc9000d9b40d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:413 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 4 locks held by syz.4.1505/9912: #0: ffff8880b8e3aad8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537 #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xda/0x3b0 kernel/trace/bpf_trace.c:2324 #2: ffffc9000d9b40d8 (&rb->spinlock){..-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:413 #3: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #3: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #3: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #3: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xda/0x3b0 kernel/trace/bpf_trace.c:2324 stack backtrace: CPU: 0 PID: 9912 Comm: syz.4.1505 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 __lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:413 ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:464 [inline] bpf_ringbuf_reserve+0x58/0x70 kernel/bpf/ringbuf.c:456 bpf_prog_3362e2a88a9dce80+0x2d/0x4a bpf_dispatcher_nop_func include/linux/bpf.h:1012 [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:2285 [inline] bpf_trace_run2+0x30a/0x3b0 kernel/trace/bpf_trace.c:2324 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 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xb0/0xf0 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:413 ____bpf_ringbuf_output kernel/bpf/ringbuf.c:539 [inline] bpf_ringbuf_output+0x65/0x1e0 kernel/bpf/ringbuf.c:529 bpf_prog_10f224e5249c74f5+0x43/0x4c bpf_dispatcher_nop_func include/linux/bpf.h:1012 [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:2285 [inline] bpf_trace_run2+0x30a/0x3b0 kernel/trace/bpf_trace.c:2324 trace_tlb_flush+0x143/0x190 include/trace/events/tlb.h:38 switch_mm_irqs_off+0x758/0xb10 arch/x86/mm/tlb.c:-1 context_switch kernel/sched/core.c:5229 [inline] __schedule+0xe99/0x40b0 kernel/sched/core.c:6561 schedule+0xb9/0x180 kernel/sched/core.c:6637 futex_wait_queue+0x134/0x1b0 kernel/futex/waitwake.c:355 futex_wait+0x19b/0x530 kernel/futex/waitwake.c:656 do_futex+0x310/0x320 kernel/futex/syscalls.c:106 __do_sys_futex kernel/futex/syscalls.c:183 [inline] __se_sys_futex+0x14a/0x440 kernel/futex/syscalls.c:164 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: 0033:0x7fd586d8eec9 Code: Unable to access opcode bytes at 0x7fd586d8ee9f. RSP: 002b:00007ffc776c3848 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 000000000006651b RCX: 00007fd586d8eec9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fd586fe5fac RBP: 0000000000000032 R08: 000547b5f1cdcdf6 R09: 00000001776c3b3f R10: 00007ffc776c3940 R11: 0000000000000246 R12: 00007fd586fe5fac R13: 00007ffc776c3940 R14: 000000000006654d R15: 00007ffc776c3960