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| author | Anthony Yznaga <anthony.yznaga@oracle.com> | 2018-12-28 00:37:31 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:50 -0800 |
| commit | 144552ff8995dd34d049a203d636b259ab751137 (patch) | |
| tree | 3e3ed4aa4afc2e22c12120be581e1846b864b4db | |
| parent | b6fb87b8e3ff1ef6bcf68470f24a97c984554d5a (diff) | |
| download | linux-144552ff8995dd34d049a203d636b259ab751137.tar.bz2 | |
/proc/kpagecount: return 0 for special pages that are never mapped
Certain pages that are never mapped to userspace have a type indicated in
the page_type field of their struct pages (e.g. PG_buddy). page_type
overlaps with _mapcount so set the count to 0 and avoid calling
page_mapcount() for these pages.
[anthony.yznaga@oracle.com: incorporate feedback from Matthew Wilcox]
Link: http://lkml.kernel.org/r/1544481313-27318-1-git-send-email-anthony.yznaga@oracle.com
Link: http://lkml.kernel.org/r/1543963526-27917-1-git-send-email-anthony.yznaga@oracle.com
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Miles Chen <miles.chen@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/page.c | 2 | ||||
| -rw-r--r-- | include/linux/page-flags.h | 6 |
2 files changed, 7 insertions, 1 deletions
diff --git a/fs/proc/page.c b/fs/proc/page.c index 6c517b11acf8..40b05e0d4274 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -46,7 +46,7 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf, ppage = pfn_to_page(pfn); else ppage = NULL; - if (!ppage || PageSlab(ppage)) + if (!ppage || PageSlab(ppage) || page_has_type(ppage)) pcount = 0; else pcount = page_mapcount(ppage); diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 50ce1bddaf56..39b4494e29f1 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -669,6 +669,7 @@ PAGEFLAG_FALSE(DoubleMap) #define PAGE_TYPE_BASE 0xf0000000 /* Reserve 0x0000007f to catch underflows of page_mapcount */ +#define PAGE_MAPCOUNT_RESERVE -128 #define PG_buddy 0x00000080 #define PG_balloon 0x00000100 #define PG_kmemcg 0x00000200 @@ -677,6 +678,11 @@ PAGEFLAG_FALSE(DoubleMap) #define PageType(page, flag) \ ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) +static inline int page_has_type(struct page *page) +{ + return (int)page->page_type < PAGE_MAPCOUNT_RESERVE; +} + #define PAGE_TYPE_OPS(uname, lname) \ static __always_inline int Page##uname(struct page *page) \ { \ |