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

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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: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>>
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>
This commit is contained in:
Naoya Horiguchi 2016-03-17 14:17:41 -07:00 committed by Linus Torvalds
parent 12580e4b54
commit 832fc1de01
4 changed files with 6 additions and 7 deletions
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6
fs/proc/page.c
View File

@ -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;

2
include/linux/page-flags.h
View File

@ -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)

3
mm/internal.h
View File

@ -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

2
mm/page_alloc.c
View File

@ -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