The patch titled
Subject: /proc/kpagecount: return 0 for special pages that are never mapped
has been added to the -mm tree. Its filename is
proc-kpagecount-return-0-for-special-pages-that-are-never-mapped.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-kpagecount-return-0-for-special-pages-that-are-never-mapped.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-kpagecount-return-0-for-special-pages-that-are-never-mapped.patch
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------------------------------------------------------
From: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
Subject: /proc/kpagecount: return 0 for special pages that are never mapped
Certain pages that are never mapped to userspace have a type indicated in
the page_type field of their struct pages (e.g. PG_buddy). page_type
overlaps with _mapcount so set the count to 0 and avoid calling
page_mapcount() for these pages.
Link: http://lkml.kernel.org/r/1543963526-27917-1-git-send-email-anthony.yznaga@xxxxxxxxxx
Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Miles Chen <miles.chen@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/page.c | 2 +-
include/linux/page-flags.h | 7 +++++++
2 files changed, 8 insertions(+), 1 deletion(-)
--- a/fs/proc/page.c~proc-kpagecount-return-0-for-special-pages-that-are-never-mapped
+++ a/fs/proc/page.c
@@ -46,7 +46,7 @@ static ssize_t kpagecount_read(struct fi
ppage = pfn_to_page(pfn);
else
ppage = NULL;
- if (!ppage || PageSlab(ppage))
+ if (!ppage || PageSlab(ppage) || page_has_type(ppage))
pcount = 0;
else
pcount = page_mapcount(ppage);
--- a/include/linux/page-flags.h~proc-kpagecount-return-0-for-special-pages-that-are-never-mapped
+++ a/include/linux/page-flags.h
@@ -673,10 +673,17 @@ PAGEFLAG_FALSE(DoubleMap)
#define PG_balloon 0x00000100
#define PG_kmemcg 0x00000200
#define PG_table 0x00000400
+#define PAGE_TYPE_ALL (PG_buddy | PG_balloon | PG_kmemcg | PG_table)
#define PageType(page, flag) \
((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
+static inline int page_has_type(struct page *page)
+{
+ return (PageType(page, 0) &&
+ ((page->page_type & PAGE_TYPE_ALL) != PAGE_TYPE_ALL));
+}
+
#define PAGE_TYPE_OPS(uname, lname) \
static __always_inline int Page##uname(struct page *page) \
{ \
_
Patches currently in -mm which might be from anthony.yznaga@xxxxxxxxxx are
tools-vm-page-typesc-fix-kpagecount-returned-fewer-pages-than-expected-failures.patch
proc-kpagecount-return-0-for-special-pages-that-are-never-mapped.patch
