sched/topology: Fix exceptional memory access in sd_llc_free_all()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6YJJQ
CVE: NA

----------------------------------------

The function sd_llc_free_all() will be called to release allocated
resources when space allocation for the scheduling domain
structure fails. However, this function did not check if sd
is a null pointer when releasing sdd resources, resulting in
an error: "Unable to handle kernel paging request at virtual
address".

Fix this issue by adding null pointer discrimination.

Fixes: 79bec4c6 ("sched/topology: Provide hooks to allocate data shared per LLC")
Signed-off-by: NXia Fukun <xiafukun@huawei.com>
Reviewed-by: Nsongping yu <yusongping@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>
(cherry picked from commit d73bbd3f)

kernel/sched/topology.c

@@ -2140,7 +2140,7 @@ static void sd_llc_free_all(const struct cpumask *cpu_map)
 
 	for_each_sd_topology(tl) {
 		sdd = &tl->data;
-		if (!sdd)
+		if (!sdd || !sdd->sd)
 			continue;
 		for_each_cpu(j, cpu_map) {
 			sd = *per_cpu_ptr(sdd->sd, j);