mm: handle hashdist initialization in mm/mm_init.c

The hashdist variable must be initialized before the first call to
alloc_large_system_hash() and free_area_init() looks like a better place
for it than page_alloc_init().

Move hashdist handling to mm/mm_init.c

Link: https://lkml.kernel.org/r/20230321170513.2401534-5-rppt@kernel.orgSigned-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mm_init.c

@@ -607,6 +607,25 @@ int __meminit early_pfn_to_nid(unsigned long pfn)
 
 	return nid;
 }
+
+int hashdist = HASHDIST_DEFAULT;
+
+static int __init set_hashdist(char *str)
+{
+	if (!str)
+		return 0;
+	hashdist = simple_strtoul(str, &str, 0);
+	return 1;
+}
+__setup("hashdist=", set_hashdist);
+
+static inline void fixup_hashdist(void)
+{
+	if (num_node_state(N_MEMORY) == 1)
+		hashdist = 0;
+}
+#else
+static inline void fixup_hashdist(void) {}
 #endif /* CONFIG_NUMA */
 
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
@@ -1855,6 +1874,9 @@ void __init free_area_init(unsigned long *max_zone_pfn)
 	}
 
 	memmap_init();
+
+	/* disable hash distribution for systems with a single node */
+	fixup_hashdist();
 }
 
 /**

mm/page_alloc.c

@@ -6393,28 +6393,10 @@ static int page_alloc_cpu_online(unsigned int cpu)
 	return 0;
 }
 
-#ifdef CONFIG_NUMA
-int hashdist = HASHDIST_DEFAULT;
-
-static int __init set_hashdist(char *str)
-{
-	if (!str)
-		return 0;
-	hashdist = simple_strtoul(str, &str, 0);
-	return 1;
-}
-__setup("hashdist=", set_hashdist);
-#endif
-
 void __init page_alloc_init(void)
 {
 	int ret;
 
-#ifdef CONFIG_NUMA
-	if (num_node_state(N_MEMORY) == 1)
-		hashdist = 0;
-#endif
-
 	ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC,
 					"mm/page_alloc:pcp",
 					page_alloc_cpu_online,