diff options
| author |   Matthew Wilcox <mawilcox@microsoft.com> | 2018-06-07 17:08:35 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-07 17:34:37 -0700 |
| commit | b21999da02f891aafa362252f4db7ba5c34a9a8d (patch) | |
| tree | 9e105640596888be72a145b04d147bea5e318d08 /include/linux/mm_types.h | |
| parent | mm: move 'private' union within struct page (diff) | |
| download | linux-dev-b21999da02f891aafa362252f4db7ba5c34a9a8d.tar.xz linux-dev-b21999da02f891aafa362252f4db7ba5c34a9a8d.zip | |
mm: move _refcount out of struct page union
Keeping the refcount in the union only encourages people to put something
else in the union which will overlap with _refcount and eventually explode
messily. pahole reports no fields change location.
Link: http://lkml.kernel.org/r/20180518194519.3820-7-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/mm_types.h')
| -rw-r--r-- | include/linux/mm_types.h | 25 |
1 files changed, 10 insertions, 15 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index bcc5ee8b7b07..0b0c0e224011 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -113,7 +113,13 @@ struct page { }; }; - union { + union { /* This union is 4 bytes in size. */ + /* + * If the page can be mapped to userspace, encodes the number + * of times this page is referenced by a page table. + */ + atomic_t _mapcount; + /* * If the page is neither PageSlab nor mappable to userspace, * the value stored here may help determine what this page @@ -124,22 +130,11 @@ struct page { unsigned int active; /* SLAB */ int units; /* SLOB */ - - struct { /* Page cache */ - /* - * Count of ptes mapped in mms, to show when - * page is mapped & limit reverse map searches. - */ - atomic_t _mapcount; - - /* - * Usage count, *USE WRAPPER FUNCTION* when manual - * accounting. See page_ref.h - */ - atomic_t _refcount; - }; }; + /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */ + atomic_t _refcount; + /* * WARNING: bit 0 of the first word encode PageTail(). That means * the rest users of the storage space MUST NOT use the bit to |