linux-kernel - [PATCH v2 1/4] mm, page_owner: handle THP splits correctly

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Message-Id: <20190820131828.22684-2-vbabka@suse.cz>
Date:   Tue, 20 Aug 2019 15:18:25 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Michal Hocko <mhocko@...nel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Matthew Wilcox <willy@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        stable@...r.kernel.org
Subject: [PATCH v2 1/4] 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().

Fixes: a9627bc5e34e ("mm/page_owner: introduce split_page_owner and replace manual handling")
Reported-by: Kirill A. Shutemov <kirill@...temov.name>
Cc: stable@...r.kernel.org
Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/huge_memory.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 738065f765ab..de1f15969e27 100644
--- a/mm/huge_memory.c
+++ b/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 page *page, struct list_head *list,
 	}
 
 	ClearPageCompound(head);
+
+	split_page_owner(head, HPAGE_PMD_ORDER);
+
 	/* See comment in __split_huge_page_tail() */
 	if (PageAnon(head)) {
 		/* Additional pin to swap cache */
-- 
2.22.0