From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id B57C06B0062 for ; Thu, 12 Nov 2009 18:14:04 -0500 (EST) Date: Thu, 12 Nov 2009 23:13:59 +0000 (GMT) From: Hugh Dickins Subject: [PATCH 1/6] ksm: three remove_rmap_item_from_tree cleanups In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Izik Eidus , Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 1. remove_rmap_item_from_tree() is called as a precaution from various places: don't dirty the rmap_item cacheline unnecessarily, just mask the flags out of the address when they have been set. 2. First get_next_rmap_item() removes an unstable rmap_item from its tree, then shortly afterwards cmp_and_merge_page() removes a stable rmap_item from its tree: it's easier just to do both at once (but definitely keep the BUG_ON(age > 1) which guards against a future omission). 3. When cmp_and_merge_page() moves an rmap_item from unstable to stable tree, it does its own rb_erase() and accounting: that's better expressed by remove_rmap_item_from_tree(). Signed-off-by: Hugh Dickins --- mm/ksm.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) --- ksm0/mm/ksm.c 2009-11-10 09:06:23.000000000 +0000 +++ ksm1/mm/ksm.c 2009-11-12 15:28:36.000000000 +0000 @@ -453,6 +453,7 @@ static void remove_rmap_item_from_tree(s } rmap_item->next = NULL; + rmap_item->address &= PAGE_MASK; } else if (rmap_item->address & NODE_FLAG) { unsigned char age; @@ -467,11 +468,11 @@ static void remove_rmap_item_from_tree(s BUG_ON(age > 1); if (!age) rb_erase(&rmap_item->node, &root_unstable_tree); + ksm_pages_unshared--; + rmap_item->address &= PAGE_MASK; } - rmap_item->address &= PAGE_MASK; - cond_resched(); /* we're called from many long loops */ } @@ -1086,8 +1087,7 @@ static void cmp_and_merge_page(struct pa unsigned int checksum; int err; - if (in_stable_tree(rmap_item)) - remove_rmap_item_from_tree(rmap_item); + remove_rmap_item_from_tree(rmap_item); /* We first start with searching the page inside the stable tree */ tree_rmap_item = stable_tree_search(page, page2, rmap_item); @@ -1143,9 +1143,7 @@ static void cmp_and_merge_page(struct pa * tree, and insert it instead as new node in the stable tree. */ if (!err) { - rb_erase(&tree_rmap_item->node, &root_unstable_tree); - tree_rmap_item->address &= ~NODE_FLAG; - ksm_pages_unshared--; + remove_rmap_item_from_tree(tree_rmap_item); /* * If we fail to insert the page into the stable tree, @@ -1174,11 +1172,8 @@ static struct rmap_item *get_next_rmap_i while (cur != &mm_slot->rmap_list) { rmap_item = list_entry(cur, struct rmap_item, link); - if ((rmap_item->address & PAGE_MASK) == addr) { - if (!in_stable_tree(rmap_item)) - remove_rmap_item_from_tree(rmap_item); + if ((rmap_item->address & PAGE_MASK) == addr) return rmap_item; - } if (rmap_item->address > addr) break; cur = cur->next; -- 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: email@kvack.org