mm: compaction: remove unneeded return value of kcompactd_run

Patch series "A few cleanup and fixup patches for compaction".

This series contains a few patches to clean up some obsolete comment,
remove unneeded return value and so on.  Also we fix the possible NULL
pointer dereference.  More details can be found in the respective
changelogs.


This patch (of 12):

The return value of kcompactd_run() is unused now.  Clean it up.

Link: https://lkml.kernel.org/r/20220418141253.24298-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220418141253.24298-2-linmiaohe@huawei.comSigned-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Cc; Mel Gorman <mgorman@techsingularity.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Pintu Kumar <pintu@codeaurora.org>
Cc: Charan Teja Kalla <charante@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

include/linux/compaction.h

@@ -177,7 +177,7 @@ static inline bool compaction_withdrawn(enum compact_result result)
 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 					int alloc_flags);
 
-extern int kcompactd_run(int nid);
+extern void kcompactd_run(int nid);
 extern void kcompactd_stop(int nid);
 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
 
@@ -212,9 +212,8 @@ static inline bool compaction_withdrawn(enum compact_result result)
 	return true;
 }
 
-static inline int kcompactd_run(int nid)
+static inline void kcompactd_run(int nid)
 {
-	return 0;
 }
 static inline void kcompactd_stop(int nid)
 {

mm/compaction.c

@@ -3016,21 +3016,18 @@ static int kcompactd(void *p)
  * This kcompactd start function will be called by init and node-hot-add.
  * On node-hot-add, kcompactd will moved to proper cpus if cpus are hot-added.
  */
-int kcompactd_run(int nid)
+void kcompactd_run(int nid)
 {
 	pg_data_t *pgdat = NODE_DATA(nid);
-	int ret = 0;
 
 	if (pgdat->kcompactd)
-		return 0;
+		return;
 
 	pgdat->kcompactd = kthread_run(kcompactd, pgdat, "kcompactd%d", nid);
 	if (IS_ERR(pgdat->kcompactd)) {
 		pr_err("Failed to start kcompactd on node %d\n", nid);
-		ret = PTR_ERR(pgdat->kcompactd);
 		pgdat->kcompactd = NULL;
 	}
-	return ret;
 }
 
 /*