From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752068Ab1EKRRL (ORCPT ); Wed, 11 May 2011 13:17:11 -0400 Received: from mail-pv0-f174.google.com ([74.125.83.174]:64061 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751719Ab1EKRRG (ORCPT ); Wed, 11 May 2011 13:17:06 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=BVNqtNj2Rqp2lz+1Xs1aHwbkmudTFNrLAlMilUTNngWkbNsmrhywVqGm+Gonqi2QsM iuVg1dnb0caQ82fuZ9dx/7exoIpfbmGtouGhyAzfx/CxE2xW+vMGoVeraTW1V/N/CrHw fEjw+a5DrFYvyQVDfaGM9rxXhUQWgapib36pg= From: Minchan Kim To: Andrew Morton Cc: linux-mm , LKML , Johannes Weiner , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Mel Gorman , Rik van Riel , Andrea Arcangeli , Minchan Kim Subject: [PATCH v1 01/10] Make clear description of isolate/putback functions Date: Thu, 12 May 2011 02:16:40 +0900 Message-Id: X-Mailer: git-send-email 1.7.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 e4a5c91..a04f68a 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 292582c..a6a87c0 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -555,10 +555,10 @@ 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. @@ -1200,6 +1200,10 @@ 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) { -- 1.7.1