[patch 08/11] mm, page_owner: handle THP splits correctly

[akpm@linux-foundation.org]

From: Vlastimil Babka <vbabka@suse.cz>
Subject: mm, page_owner: handle THP splits correctly

THP splitting path is missing the split_page_owner() call that
split_page() has.  As a result, split THP pages are wrongly reported in
the page_owner file as order-9 pages.  Furthermore when the former head
page is freed, the remaining former tail pages are not listed in the
page_owner file at all.  This patch fixes that by adding the
split_page_owner() call into __split_huge_page().

Link: http://lkml.kernel.org/r/20190820131828.22684-2-vbabka@suse.cz
Fixes: a9627bc5e34e ("mm/page_owner: introduce split_page_owner and replace manual handling")
Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/huge_memory.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/mm/huge_memory.c~mm-page_owner-handle-thp-splits-correctly
+++ a/mm/huge_memory.c
@@ -32,6 +32,7 @@
 #include <linux/shmem_fs.h>
 #include <linux/oom.h>
 #include <linux/numa.h>
+#include <linux/page_owner.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -2516,6 +2517,9 @@ static void __split_huge_page(struct pag
 	}
 
 	ClearPageCompound(head);
+
+	split_page_owner(head, HPAGE_PMD_ORDER);
+
 	/* See comment in __split_huge_page_tail() */
 	if (PageAnon(head)) {
 		/* Additional pin to swap cache */
_