From 5f9f6c96ccb344c4ca0dd9c1f06bd21db93fda51 Mon Sep 17 00:00:00 2001 Message-Id: <5f9f6c96ccb344c4ca0dd9c1f06bd21db93fda51.1306689214.git.minchan.kim@gmail.com> In-Reply-To: References: From: Minchan Kim Date: Sun, 29 May 2011 08:22:01 +0900 Subject: [PATCH v2 01/10] Make clear description of isolate/putback functions Commonly, putback_lru_page is used with isolated_lru_page. The isolated_lru_page picks the page in middle of LRU and putback_lru_page insert the lru in head of LRU. It means it could make LRU churning so we have to be very careful. Let's clear description of isolate/putback functions. Cc: Mel Gorman Cc: Rik van Riel Cc: Andrea Arcangeli Reviewed-by: KAMEZAWA Hiroyuki Acked-by: Johannes Weiner Reviewed-by: KOSAKI Motohiro Signed-off-by: Minchan Kim --- mm/migrate.c | 2 +- mm/vmscan.c | 8 ++++++-- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 34132f8..819d233 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -68,7 +68,7 @@ int migrate_prep_local(void) } /* - * Add isolated pages on the list back to the LRU under page lock + * Add isolated pages on the list back to the LRU's head under page lock * to avoid leaking evictable pages back onto unevictable list. */ void putback_lru_pages(struct list_head *l) diff --git a/mm/vmscan.c b/mm/vmscan.c index 8bfd450..a658dde 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -551,10 +551,10 @@ int remove_mapping(struct address_space *mapping, struct page *page) } /** - * putback_lru_page - put previously isolated page onto appropriate LRU list + * putback_lru_page - put previously isolated page onto appropriate LRU list's head * @page: page to be put back to appropriate lru list * - * Add previously isolated @page to appropriate LRU list. + * Add previously isolated @page to appropriate LRU list's head * Page may still be unevictable for other reasons. * * lru_lock must not be held, interrupts must be enabled. @@ -1196,6 +1196,10 @@ static unsigned long clear_active_flags(struct list_head *page_list, * without a stable reference). * (2) the lru_lock must not be held. * (3) interrupts must be enabled. + * + * NOTE : This function removes the page from LRU list and putback_lru_page + * insert the page to LRU list's head. It means it makes LRU churing so you + * have to use the function carefully. */ int isolate_lru_page(struct page *page) { -- 1.7.0.4