[PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages()

[Anshuman Khandual <anshuman.khandual@arm.com>]

Having unmovable pages on a given pageblock should be reported correctly
when required with REPORT_FAILURE flag. But there can be a scenario where a
reserved page in the page block will get reported as a generic "unmovable"
reason code. Instead this should be changed to a more appropriate reason
code like "Reserved page".

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 mm/page_alloc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 15c2050c629b..fbf93ea119d2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8206,8 +8206,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 
 		page = pfn_to_page(check);
 
-		if (PageReserved(page))
+		if (PageReserved(page)) {
+			reason = "Reserved page";
 			goto unmovable;
+		}
 
 		/*
 		 * If the zone is movable and we have ruled out all reserved
-- 
2.20.1