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| -rw-r--r-- | mm/page_alloc.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 40baa2421136..a04dc456ed8d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5043,6 +5043,26 @@ static inline void free_the_page(struct page *page, unsigned int order) __free_pages_ok(page, order, FPI_NONE); } +/** + * __free_pages - Free pages allocated with alloc_pages(). + * @page: The page pointer returned from alloc_pages(). + * @order: The order of the allocation. + * + * This function can free multi-page allocations that are not compound + * pages. It does not check that the @order passed in matches that of + * the allocation, so it is easy to leak memory. Freeing more memory + * than was allocated will probably emit a warning. + * + * If the last reference to this page is speculative, it will be released + * by put_page() which only frees the first page of a non-compound + * allocation. To prevent the remaining pages from being leaked, we free + * the subsequent pages here. If you want to use the page's reference + * count to decide when to free the allocation, you should allocate a + * compound page, and use put_page() instead of __free_pages(). + * + * Context: May be called in interrupt context or while holding a normal + * spinlock, but not in NMI context or while holding a raw spinlock. + */ void __free_pages(struct page *page, unsigned int order) { if (put_page_testzero(page)) |