============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.4.1084/8754 is trying to acquire lock: ffffc9001d1400d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:415 but task is already holding lock: ffffc9001bf350d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:415 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.4.1084/8754: #0: ffff88802e525598 (&u->iolock){+.+.}-{3:3}, at: __unix_dgram_recvmsg+0x1df/0xd70 net/unix/af_unix.c:2448 #1: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #1: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #1: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #1: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xda/0x3b0 kernel/trace/bpf_trace.c:2324 #2: ffffc9001bf350d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1c4/0x5a0 kernel/bpf/ringbuf.c:415 #3: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #3: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #3: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #3: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xda/0x3b0 kernel/trace/bpf_trace.c:2324 stack backtrace: CPU: 1 PID: 8754 Comm: syz.4.1084 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 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:415 ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:466 [inline] bpf_ringbuf_reserve+0x58/0x70 kernel/bpf/ringbuf.c:458 bpf_prog_fe0ed97373b08409+0x25/0x42 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 __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:415 ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:466 [inline] bpf_ringbuf_reserve+0x58/0x70 kernel/bpf/ringbuf.c:458 bpf_prog_fe0ed97373b08409+0x25/0x42 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+0x123/0x170 include/trace/events/lock.h:122 __mutex_lock_common kernel/locking/mutex.c:612 [inline] __mutex_lock+0x194/0xaf0 kernel/locking/mutex.c:747 __unix_dgram_recvmsg+0x1df/0xd70 net/unix/af_unix.c:2448 ____sys_recvmsg+0x292/0x580 net/socket.c:-1 ___sys_recvmsg+0x1b2/0x510 net/socket.c:2780 do_recvmmsg+0x359/0x7d0 net/socket.c:2874 __sys_recvmmsg net/socket.c:2953 [inline] __do_sys_recvmmsg net/socket.c:2976 [inline] __se_sys_recvmmsg net/socket.c:2969 [inline] __x64_sys_recvmmsg+0x18d/0x240 net/socket.c:2969 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: 0033:0x7f1fb8f8f749 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:00007f1fb9dd1038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007f1fb91e6090 RCX: 00007f1fb8f8f749 RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003 RBP: 00007f1fb9013f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1fb91e6128 R14: 00007f1fb91e6090 R15: 00007ffc81571d08