From: Joonsoo Kim <[email protected]> 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 <[email protected]> --- 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
