Re: [PATCH v4 1/3] mm: introduce compaction and migration for virtio ballooned pages
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-07-18 22:46:12
Also in:
lkml, virtualization
On Tue, 17 Jul 2012 13:50:41 -0300 Rafael Aquini [off-list ref] wrote:
quoted hunk ↗ jump to hunk
This patch introduces the helper functions as well as the necessary changes to teach compaction and migration bits how to cope with pages which are part of a guest memory balloon, in order to make them movable by memory compaction procedures. ...--- a/include/linux/mm.h +++ b/include/linux/mm.h@@ -1629,5 +1629,20 @@ static inline unsigned int debug_guardpage_minorder(void) { return 0; } static inline bool page_is_guard(struct page *page) { return false; } #endif /* CONFIG_DEBUG_PAGEALLOC */ +#if (defined(CONFIG_VIRTIO_BALLOON) || \ + defined(CONFIG_VIRTIO_BALLOON_MODULE)) && defined(CONFIG_COMPACTION) +extern bool putback_balloon_page(struct page *); +extern struct address_space *balloon_mapping; + +static inline bool is_balloon_page(struct page *page) +{ + return (page->mapping == balloon_mapping) ? true : false;
You can simply do return page->mapping == balloon_mapping;
+}
+#else
+static inline bool is_balloon_page(struct page *page) { return false; }
+static inline bool isolate_balloon_page(struct page *page) { return false; }
+static inline bool putback_balloon_page(struct page *page) { return false; }
+#endif /* (VIRTIO_BALLOON || VIRTIO_BALLOON_MODULE) && COMPACTION */This means that if CONFIG_VIRTIO_BALLOON=y and CONFIG_COMPACTION=n, is_balloon_page() will always return NULL. IOW, no pages are balloon pages! This is wrong. I'm not sure what to do about this, apart from renaming the function to is_compactible_balloon_page() or something similarly aawkward. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>