Compound pages can be on the LRU. This means that the page pointer to the head page is on a pagevec. In that case we need full LRU processing for the page in release_pages(). The check for compound pages in release_pages() was introduced by Nick Piggin to make sure that the page count in tail pages is not going negative. Well we can now explicitly check for the tail page. The head page should be processes like a regular page in order to support higher order page cache pages. Signed-off-by: Christoph Lameter --- mm/swap.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) Index: linux-2.6.21-rc7/mm/swap.c =================================================================== --- linux-2.6.21-rc7.orig/mm/swap.c 2007-04-24 09:40:16.000000000 -0700 +++ linux-2.6.21-rc7/mm/swap.c 2007-04-24 09:42:27.000000000 -0700 @@ -263,7 +263,13 @@ void release_pages(struct page **pages, for (i = 0; i < nr; i++) { struct page *page = pages[i]; - if (unlikely(PageCompound(page))) { + /* + * If we have a tail page on the LRU then we need to + * decrement the page count of the head page. There + * is no further need to do anything since tail pages + * cannot be on the LRU. + */ + if (unlikely(PageTail(page))) { if (zone) { spin_unlock_irq(&zone->lru_lock); zone = NULL; -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/