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Commit 56873f43 authored by Wang, Yalin's avatar Wang, Yalin Committed by Linus Torvalds
Browse files

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: default avatarYalin Wang <yalin.wang@sonymobile.com>
Acked-by: default avatarKirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1d148e21

Documentation/vm/pagemap.txt

+8 −0
Original line number Diff line number Diff line
@@ -62,6 +62,8 @@ There are three components to pagemap: 
    20. NOPAGE

    21. KSM

    22. THP

    23. BALLOON

    24. ZERO_PAGE



Short descriptions to the page flags:
@@ -102,6 +104,12 @@ Short descriptions to the page flags: 
22. THP

    contiguous pages which construct transparent hugepages



23. BALLOON

    balloon compaction page



24. ZERO_PAGE

    zero page for pfn_zero or huge_zero page



    [IO related page flags]

 1. ERROR     IO error occurred

 3. UPTODATE  page has up-to-date data

fs/proc/page.c

+13 −3
Original line number Diff line number Diff line
@@ -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 @@ u64 stable_page_flags(struct page *page) 
	 * 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))))

	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

include/linux/huge_mm.h

+12 −0
Original line number Diff line number Diff line
@@ -157,6 +157,13 @@ static inline int hpage_nr_pages(struct page *page) 
extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,

				unsigned long addr, pmd_t pmd, pmd_t *pmdp);



extern struct page *huge_zero_page;



static inline bool is_huge_zero_page(struct page *page)

{

	return ACCESS_ONCE(huge_zero_page) == page;

}



#else /* CONFIG_TRANSPARENT_HUGEPAGE */

#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })

#define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
@@ -206,6 +213,11 @@ static inline int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_str 
	return 0;

}



static inline bool is_huge_zero_page(struct page *page)

{

	return false;

}



#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



#endif /* _LINUX_HUGE_MM_H */

include/uapi/linux/kernel-page-flags.h

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#define KPF_KSM			21

#define KPF_THP			22

#define KPF_BALLOON		23

#define KPF_ZERO_PAGE		24





#endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */

mm/huge_memory.c

+1 −6
Original line number Diff line number Diff line
@@ -171,12 +171,7 @@ static int start_khugepaged(void) 
}



static atomic_t huge_zero_refcount;

static struct page *huge_zero_page __read_mostly;



static inline bool is_huge_zero_page(struct page *page)

{

	return ACCESS_ONCE(huge_zero_page) == page;

}

struct page *huge_zero_page __read_mostly;



static inline bool is_huge_zero_pmd(pmd_t pmd)

{