kpagecount: add slab page checking because _mapcount is in a union

Add a PageSlab() check before adding the _mapcount value to /kpagecount.
page->_mapcount is in a union with the SLAB structure so for pages
controlled by SLAB, page_mapcount() returns nonsense.

Signed-off-by: Petr Holasek <pholasek@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Petr Holasek 2011-01-12 17:00:34 -08:00 коммит произвёл Linus Torvalds
Родитель c6a3405846
Коммит a6fc86d2b4
1 изменённых файлов: 1 добавлений и 1 удалений

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@ -40,7 +40,7 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf,
ppage = pfn_to_page(pfn);
else
ppage = NULL;
if (!ppage)
if (!ppage || PageSlab(ppage))
pcount = 0;
else
pcount = page_mapcount(ppage);