============================================ WARNING: possible recursive locking detected 6.11.0-syzkaller-12113-ge7ed34365879 #0 Not tainted -------------------------------------------- syz.5.6/5378 is trying to acquire lock: ffffc900090890d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1ea/0x600 kernel/bpf/ringbuf.c:427 but task is already holding lock: ffffc90004d210d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1ea/0x600 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 4 locks held by syz.5.6/5378: #0: ffff88802d590958 (&sighand->siglock){-...}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:376 [inline] #0: ffff88802d590958 (&sighand->siglock){-...}-{2:2}, at: get_signal+0x258/0x1740 kernel/signal.c:2706 #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2317 [inline] #1: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run3+0x24c/0x5a0 kernel/trace/bpf_trace.c:2360 #2: ffffc90004d210d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1ea/0x600 kernel/bpf/ringbuf.c:427 #3: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #3: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #3: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2317 [inline] #3: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x1fc/0x540 kernel/trace/bpf_trace.c:2359 stack backtrace: CPU: 1 UID: 0 PID: 5378 Comm: syz.5.6 Not tainted 6.11.0-syzkaller-12113-ge7ed34365879 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3037 check_deadlock kernel/locking/lockdep.c:3089 [inline] validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3891 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x1ea/0x600 kernel/bpf/ringbuf.c:427 ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:478 [inline] bpf_ringbuf_reserve+0x5c/0x70 kernel/bpf/ringbuf.c:470 bpf_prog_fe0ed97373b08409+0x2e/0x4f bpf_dispatcher_nop_func include/linux/bpf.h:1257 [inline] __bpf_prog_run include/linux/filter.h:701 [inline] bpf_prog_run include/linux/filter.h:708 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2318 [inline] bpf_trace_run2+0x2ee/0x540 kernel/trace/bpf_trace.c:2359 trace_contention_end+0x114/0x140 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0xb7e/0xdb0 kernel/locking/qspinlock.c:557 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [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+0x272/0x370 kernel/locking/spinlock_debug.c:116 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xe1/0x120 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x1ea/0x600 kernel/bpf/ringbuf.c:427 ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:478 [inline] bpf_ringbuf_reserve+0x5c/0x70 kernel/bpf/ringbuf.c:470 bpf_prog_fe0ed97373b08409+0x2e/0x4f bpf_dispatcher_nop_func include/linux/bpf.h:1257 [inline] __bpf_prog_run include/linux/filter.h:701 [inline] bpf_prog_run include/linux/filter.h:708 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2318 [inline] bpf_trace_run3+0x33c/0x5a0 kernel/trace/bpf_trace.c:2360 __traceiter_kmem_cache_free+0x35/0x50 include/trace/events/kmem.h:114 trace_kmem_cache_free include/trace/events/kmem.h:114 [inline] kmem_cache_free+0x355/0x420 mm/slub.c:4681 __sigqueue_free kernel/signal.c:451 [inline] collect_signal kernel/signal.c:594 [inline] __dequeue_signal+0x4ac/0x5c0 kernel/signal.c:616 dequeue_signal+0x1e0/0x680 kernel/signal.c:637 get_signal+0x604/0x1740 kernel/signal.c:2797 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9c7797dff9 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:00007f9c786c40e8 EFLAGS: 00000246 RAX: 0000000000000001 RBX: 00007f9c77b35f88 RCX: 00007f9c7797dff9 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f9c77b35f8c RBP: 00007f9c77b35f80 R08: 7fffffffffffffff R09: 0000000000000000 R10: 0000000000000009 R11: 0000000000000246 R12: 00007f9c77b35f8c R13: 0000000000000000 R14: 00007ffdcabd1800 R15: 00007ffdcabd18e8