syzbot

=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
kernel/events/callchain.c:163 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz.0.17/5997:
 #0: ffffffff8e3c8c80 (rcu_read_lock_trace){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c8c80 (rcu_read_lock_trace){....}-{0:0}, at: rcu_read_lock_trace include/linux/rcupdate_trace.h:58 [inline]
 #0: ffffffff8e3c8c80 (rcu_read_lock_trace){....}-{0:0}, at: bpf_prog_test_run_syscall+0x357/0xb20 net/bpf/test_run.c:1629

stack backtrace:
CPU: 0 UID: 0 PID: 5997 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x166/0x260 kernel/locking/lockdep.c:6876
 get_callchain_entry+0x278/0x3f0 kernel/events/callchain.c:163
 get_perf_callchain+0x2d6/0x980 kernel/events/callchain.c:231
 __bpf_get_stack+0x74b/0x950 kernel/bpf/stackmap.c:472
 ____bpf_get_stack kernel/bpf/stackmap.c:517 [inline]
 bpf_get_stack+0x32/0x40 kernel/bpf/stackmap.c:514
 ____bpf_get_stack_raw_tp kernel/trace/bpf_trace.c:1653 [inline]
 bpf_get_stack_raw_tp+0x1dd/0x280 kernel/trace/bpf_trace.c:1643
 bpf_prog_aa1f08ea8b241262+0x46/0x4e
 bpf_dispatcher_nop_func include/linux/bpf.h:1376 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 bpf_prog_run_pin_on_cpu include/linux/filter.h:747 [inline]
 bpf_prog_test_run_syscall+0x461/0xb20 net/bpf/test_run.c:1630
 bpf_prog_test_run kernel/bpf/syscall.c:4703 [inline]
 __sys_bpf+0x1035/0x4980 kernel/bpf/syscall.c:6182
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:6272
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8aec98f749
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:00007ffea57f3fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f8aecbe5fa0 RCX: 00007f8aec98f749
RDX: 0000000000000010 RSI: 0000200000000740 RDI: 000000000000000a
RBP: 00007f8aeca13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8aecbe5fa0 R14: 00007f8aecbe5fa0 R15: 0000000000000003
 </TASK>