rmap: support file thp

Naive approach: on mapping/unmapping the page as compound we update
->_mapcount on each 4k page.  That's not efficient, but it's not obvious
how we can optimize this.  We can look into optimization later.

PG_double_map optimization doesn't work for file pages since lifecycle
of file pages is different comparing to anon pages: file page can be
mapped again at any time.

Link: http://lkml.kernel.org/r/1466021202-61880-11-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2016-07-26 15:25:26 -07:00 committed by Linus Torvalds
parent 7267ec008b
commit dd78fedde4
6 changed files with 52 additions and 20 deletions

View file

@ -165,7 +165,7 @@ void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long, int);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long, bool);
void page_add_file_rmap(struct page *);
void page_add_file_rmap(struct page *, bool);
void page_remove_rmap(struct page *, bool);
void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,