mm:add KPF_ZERO_PAGE flag for /proc/kpageflags
Add KPF_ZERO_PAGE flag for zero_page, so that userspace processes can
detect zero_page in /proc/kpageflags, and then do memory analysis more
accurately.
Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 1e3187d..7eee2d8 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -5,6 +5,7 @@
#include <linux/ksm.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
+#include <linux/huge_mm.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/hugetlb.h>
@@ -121,9 +122,18 @@
* just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
* to make sure a given page is a thp, not a non-huge compound page.
*/
- else if (PageTransCompound(page) && (PageLRU(compound_head(page)) ||
- PageAnon(compound_head(page))))
- u |= 1 << KPF_THP;
+ else if (PageTransCompound(page)) {
+ struct page *head = compound_head(page);
+
+ if (PageLRU(head) || PageAnon(head))
+ u |= 1 << KPF_THP;
+ else if (is_huge_zero_page(head)) {
+ u |= 1 << KPF_ZERO_PAGE;
+ u |= 1 << KPF_THP;
+ }
+ } else if (is_zero_pfn(page_to_pfn(page)))
+ u |= 1 << KPF_ZERO_PAGE;
+
/*
* Caveats on high order pages: page->_count will only be set