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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/page_alloc.c
parent444eb2a449ef36fe115431ed7b71467c4563c7f1 (diff)
downloadop-kernel-dev-fe896d1878949ea92ba547587bc3075cc688fb8f.zip
op-kernel-dev-fe896d1878949ea92ba547587bc3075cc688fb8f.tar.gz
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/page_alloc.c')
-rw-r--r--mm/page_alloc.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 096a00d..30134a8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -766,7 +766,7 @@ static inline int free_pages_check(struct page *page)
bad_reason = "nonzero mapcount";
if (unlikely(page->mapping != NULL))
bad_reason = "non-NULL mapping";
- if (unlikely(atomic_read(&page->_count) != 0))
+ if (unlikely(page_ref_count(page) != 0))
bad_reason = "nonzero _count";
if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
@@ -1462,7 +1462,7 @@ static inline int check_new_page(struct page *page)
bad_reason = "nonzero mapcount";
if (unlikely(page->mapping != NULL))
bad_reason = "non-NULL mapping";
- if (unlikely(atomic_read(&page->_count) != 0))
+ if (unlikely(page_ref_count(page) != 0))
bad_reason = "nonzero _count";
if (unlikely(page->flags & __PG_HWPOISON)) {
bad_reason = "HWPoisoned (hardware-corrupted)";
@@ -3475,7 +3475,7 @@ refill:
/* Even if we own the page, we do not use atomic_set().
* This would break get_page_unless_zero() users.
*/
- atomic_add(size - 1, &page->_count);
+ page_ref_add(page, size - 1);
/* reset page count bias and offset to start of new frag */
nc->pfmemalloc = page_is_pfmemalloc(page);
@@ -3487,7 +3487,7 @@ refill:
if (unlikely(offset < 0)) {
page = virt_to_page(nc->va);
- if (!atomic_sub_and_test(nc->pagecnt_bias, &page->_count))
+ if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
goto refill;
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
@@ -3495,7 +3495,7 @@ refill:
size = nc->size;
#endif
/* OK, page count is 0, we can safely set it */
- atomic_set(&page->_count, size);
+ set_page_count(page, size);
/* reset page count bias and offset to start of new frag */
nc->pagecnt_bias = size;
@@ -6852,7 +6852,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
* This check already skips compound tails of THP
* because their page->_count is zero at all time.
*/
- if (!atomic_read(&page->_count)) {
+ if (!page_ref_count(page)) {
if (PageBuddy(page))
iter += (1 << page_order(page)) - 1;
continue;
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