mm: remove "count" parameter from has_unmovable_pages()

Now that the memory isolate notifier is gone, the parameter is always 0.
Drop it and cleanup has_unmovable_pages().

Link: http://lkml.kernel.org/r/20191114131911.11783-3-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/page-isolation.h

@@ -33,8 +33,8 @@ static inline bool is_migrate_isolate(int migratetype)
 #define MEMORY_OFFLINE	0x1
 #define REPORT_FAILURE	0x2
 
-bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
-			 int migratetype, int flags);
+bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype,
+			 int flags);
 void set_pageblock_migratetype(struct page *page, int migratetype);
 int move_freepages_block(struct zone *zone, struct page *page,
 				int migratetype, int *num_movable);

mm/memory_hotplug.c

@@ -1182,7 +1182,7 @@ static bool is_pageblock_removable_nolock(unsigned long pfn)
 	if (!zone_spans_pfn(zone, pfn))
 		return false;
 
-	return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE,
+	return !has_unmovable_pages(zone, page, MIGRATE_MOVABLE,
 				    MEMORY_OFFLINE);
 }
 

mm/page_alloc.c

@@ -8180,17 +8180,15 @@ void *__init alloc_large_system_hash(const char *tablename,
 
 /*
  * This function checks whether pageblock includes unmovable pages or not.
- * If @count is not zero, it is okay to include less @count unmovable pages
  *
  * PageLRU check without isolation or lru_lock could race so that
  * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
  * check without lock_page also may miss some movable non-lru pages at
  * race condition. So you can't expect this function should be exact.
  */
-bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
-			 int migratetype, int flags)
+bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype,
+			 int flags)
 {
-	unsigned long found;
 	unsigned long iter = 0;
 	unsigned long pfn = page_to_pfn(page);
 	const char *reason = "unmovable page";
@@ -8216,13 +8214,11 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 		goto unmovable;
 	}
 
-	for (found = 0; iter < pageblock_nr_pages; iter++) {
-		unsigned long check = pfn + iter;
-
-		if (!pfn_valid_within(check))
+	for (; iter < pageblock_nr_pages; iter++) {
+		if (!pfn_valid_within(pfn + iter))
 			continue;
 
-		page = pfn_to_page(check);
+		page = pfn_to_page(pfn + iter);
 
 		if (PageReserved(page))
 			goto unmovable;
@@ -8271,11 +8267,9 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 		if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
 			continue;
 
-		if (__PageMovable(page))
+		if (__PageMovable(page) || PageLRU(page))
 			continue;
 
-		if (!PageLRU(page))
-			found++;
 		/*
 		 * If there are RECLAIMABLE pages, we need to check
 		 * it.  But now, memory offline itself doesn't call
@@ -8289,8 +8283,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 		 * is set to both of a memory hole page and a _used_ kernel
 		 * page at boot.
 		 */
-		if (found > count)
-			goto unmovable;
+		goto unmovable;
 	}
 	return false;
 unmovable:

mm/page_isolation.c

@@ -37,7 +37,7 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
 	 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
 	 * We just check MOVABLE pages.
 	 */
-	if (!has_unmovable_pages(zone, page, 0, migratetype, isol_flags)) {
+	if (!has_unmovable_pages(zone, page, migratetype, isol_flags)) {
 		unsigned long nr_pages;
 		int mt = get_pageblock_migratetype(page);