From fe896d1878949ea92ba547587bc3075cc688fb8f Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Thu, 17 Mar 2016 14:19:26 -0700 Subject: mm: introduce page reference manipulation functions The success of CMA allocation largely depends on the success of migration and key factor of it is page reference count. Until now, page reference is manipulated by direct calling atomic functions so we cannot follow up who and where manipulate it. Then, it is hard to find actual reason of CMA allocation failure. CMA allocation should be guaranteed to succeed so finding offending place is really important. In this patch, call sites where page reference is manipulated are converted to introduced wrapper function. This is preparation step to add tracepoint to each page reference manipulation function. With this facility, we can easily find reason of CMA allocation failure. There is no functional change in this patch. In addition, this patch also converts reference read sites. It will help a second step that renames page._count to something else and prevents later attempt to direct access to it (Suggested by Andrew). Signed-off-by: Joonsoo Kim Acked-by: Michal Nazarewicz Acked-by: Vlastimil Babka Cc: Minchan Kim Cc: Mel Gorman Cc: "Kirill A. Shutemov" Cc: Sergey Senozhatsky Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/mm/gup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index d8a798d8bf50..f8d0b5e8bdfd 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -131,7 +131,7 @@ static inline void get_head_page_multiple(struct page *page, int nr) { VM_BUG_ON_PAGE(page != compound_head(page), page); VM_BUG_ON_PAGE(page_count(page) == 0, page); - atomic_add(nr, &page->_count); + page_ref_add(page, nr); SetPageReferenced(page); } -- cgit v1.2.3