Commit 832fc1de authored by Naoya Horiguchi's avatar Naoya Horiguchi Committed by Linus Torvalds
Browse files

/proc/kpageflags: return KPF_BUDDY for "tail" buddy pages 



Currently /proc/kpageflags returns nothing for "tail" buddy pages, which
is inconvenient when grasping how free pages are distributed.  This
patch sets KPF_BUDDY for such pages.

With this patch:

  $ grep MemFree /proc/meminfo ; tools/vm/page-types -b buddy
  MemFree:         3134992 kB
               flags      page-count       MB  symbolic-flags                     long-symbolic-flags
  0x0000000000000400          779272     3044  __________B_______________________________ buddy
  0x0000000000000c00            4385       17  __________BM______________________________ buddy,mmap
               total          783657     3061

783657 pages is 3134628 kB (roughly consistent with the global counter,)
so it's OK.

[akpm@linux-foundation.org: update comment, per Naoya]
Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com&gt;>
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 12580e4b

fs/proc/page.c

+4 −2
Original line number Diff line number Diff line
@@ -103,9 +103,9 @@ u64 stable_page_flags(struct page *page) 
	 * pseudo flags for the well known (anonymous) memory mapped pages

	 *

	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the

	 * simple test in page_mapcount() is not enough.

	 * simple test in page_mapped() is not enough.

	 */

	if (!PageSlab(page) && page_mapcount(page))

	if (!PageSlab(page) && page_mapped(page))

		u |= 1 << KPF_MMAP;

	if (PageAnon(page))

		u |= 1 << KPF_ANON;
@@ -148,6 +148,8 @@ u64 stable_page_flags(struct page *page) 
	 */

	if (PageBuddy(page))

		u |= 1 << KPF_BUDDY;

	else if (page_count(page) == 0 && is_free_buddy_page(page))

		u |= 1 << KPF_BUDDY;



	if (PageBalloon(page))

		u |= 1 << KPF_BALLOON;

include/linux/page-flags.h

+2 −0
Original line number Diff line number Diff line
@@ -593,6 +593,8 @@ static inline void __ClearPageBuddy(struct page *page) 
	atomic_set(&page->_mapcount, -1);

}



extern bool is_free_buddy_page(struct page *page);



#define PAGE_BALLOON_MAPCOUNT_VALUE (-256)



static inline int PageBalloon(struct page *page)

mm/internal.h

+0 −3
Original line number Diff line number Diff line
@@ -148,9 +148,6 @@ extern int __isolate_free_page(struct page *page, unsigned int order); 
extern void __free_pages_bootmem(struct page *page, unsigned long pfn,

					unsigned int order);

extern void prep_compound_page(struct page *page, unsigned int order);

#ifdef CONFIG_MEMORY_FAILURE

extern bool is_free_buddy_page(struct page *page);

#endif

extern int user_min_free_kbytes;



#if defined CONFIG_COMPACTION || defined CONFIG_CMA

mm/page_alloc.c

+0 −2
Original line number Diff line number Diff line
@@ -7152,7 +7152,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) 
}

#endif



#ifdef CONFIG_MEMORY_FAILURE

bool is_free_buddy_page(struct page *page)

{

	struct zone *zone = page_zone(page);
@@ -7171,4 +7170,3 @@ bool is_free_buddy_page(struct page *page) 


	return order < MAX_ORDER;

}
 
#endif

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