Re: [syzbot] [perf?] WARNING: suspicious RCU usage in get_callchain_entry

[Qing Wang]

#syz test

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 75495a5c3507..ee3d8ed11699 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -84,6 +84,7 @@ static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
 
 u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
+u64 bpf_get_stack_sleepable(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 
 static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size,
 				  u64 flags, const struct btf **btf,
@@ -1705,6 +1706,32 @@ static const struct bpf_func_proto bpf_get_stack_proto_raw_tp = {
 	.arg4_type	= ARG_ANYTHING,
 };
 
+BPF_CALL_4(bpf_get_stack_sleepable_raw_tp, struct bpf_raw_tracepoint_args *, args,
+	   void *, buf, u32, size, u64, flags)
+{
+	struct pt_regs *regs = get_bpf_raw_tp_regs();
+	int ret;
+
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	perf_fetch_caller_regs(regs);
+	ret = bpf_get_stack_sleepable((unsigned long) regs, (unsigned long) buf,
+				     (unsigned long) size, flags, 0);
+	put_bpf_raw_tp_regs();
+	return ret;
+}
+
+static const struct bpf_func_proto bpf_get_stack_sleepable_proto_raw_tp = {
+	.func		= bpf_get_stack_sleepable_raw_tp,
+	.gpl_only	= true,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_PTR_TO_UNINIT_MEM,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
+	.arg4_type	= ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *
 raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -1714,7 +1741,8 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	case BPF_FUNC_get_stackid:
 		return &bpf_get_stackid_proto_raw_tp;
 	case BPF_FUNC_get_stack:
-		return &bpf_get_stack_proto_raw_tp;
+		return prog->sleepable ? &bpf_get_stack_sleepable_proto_raw_tp
+				       : &bpf_get_stack_proto_raw_tp;
 	case BPF_FUNC_get_attach_cookie:
 		return &bpf_get_attach_cookie_proto_tracing;
 	default: