linux-kernel - [PATCH 4.19 85/98] mm, page_owner: handle THP splits correctly

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Message-Id: <20190827072722.471482519@linuxfoundation.org>
Date:   Tue, 27 Aug 2019 09:51:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.19 85/98] mm, page_owner: handle THP splits correctly

From: Vlastimil Babka <vbabka@...e.cz>

commit f7da677bc6e72033f0981b9d58b5c5d409fa641e upstream.

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@...temov.name>
Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Mel Gorman <mgorman@...hsingularity.net>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -33,6 +33,7 @@
 #include <linux/page_idle.h>
 #include <linux/shmem_fs.h>
 #include <linux/oom.h>
+#include <linux/page_owner.h>

 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -2477,6 +2478,9 @@ 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 radix tree of swap cache */