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authorJoonsoo Kim <iamjoonsoo.kim@lge.com>2016-03-17 14:19:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-17 15:09:34 -0700
commitfe896d1878949ea92ba547587bc3075cc688fb8f (patch)
tree582ae505611bafae117c0de8498916485699ac78 /mm/huge_memory.c
parent444eb2a449ef36fe115431ed7b71467c4563c7f1 (diff)
downloadlinux-fe896d1878949ea92ba547587bc3075cc688fb8f.tar.bz2
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 <iamjoonsoo.kim@lge.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e08b1659ff19..bb944c771c82 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2888,7 +2888,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
page = pmd_page(*pmd);
VM_BUG_ON_PAGE(!page_count(page), page);
- atomic_add(HPAGE_PMD_NR - 1, &page->_count);
+ page_ref_add(page, HPAGE_PMD_NR - 1);
write = pmd_write(*pmd);
young = pmd_young(*pmd);
dirty = pmd_dirty(*pmd);
@@ -3257,7 +3257,7 @@ static void __split_huge_page_tail(struct page *head, int tail,
struct page *page_tail = head + tail;
VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
- VM_BUG_ON_PAGE(atomic_read(&page_tail->_count) != 0, page_tail);
+ VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
/*
* tail_page->_count is zero and not changing from under us. But
@@ -3270,7 +3270,7 @@ static void __split_huge_page_tail(struct page *head, int tail,
* atomic_set() here would be safe on all archs (and not only on x86),
* it's safer to use atomic_inc().
*/
- atomic_inc(&page_tail->_count);
+ page_ref_inc(page_tail);
page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
page_tail->flags |= (head->flags &