From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Many developer already know that field for reference count of
the struct page is _count and atomic type. They would try to handle it
directly and this could break the purpose of page reference count
tracepoint. To prevent direct _count modification, this patch rename it
to _refcount and add warning message on the code. After that, developer
who need to handle reference count will find that field should not be
accessed directly.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
include/linux/mm_types.h | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 944b2b3..9e8eb5a 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -97,7 +97,11 @@ struct page {
};
int units; /* SLOB */
};
- atomic_t _count; /* Usage count, see below. */
+ /*
+ * Usage count, *USE WRAPPER FUNCTION*
+ * when manual accounting. See page_ref.h
+ */
+ atomic_t _refcount;
};
unsigned int active; /* SLAB */
};
@@ -248,7 +252,7 @@ struct page_frag_cache {
__u32 offset;
#endif
/* we maintain a pagecount bias, so that we dont dirty cache line
- * containing page->_count every time we allocate a fragment.
+ * containing page->_refcount every time we allocate a fragment.
*/
unsigned int pagecnt_bias;
bool pfmemalloc;
--
1.9.1
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>