From 93d17715a5b960d34220f2edba3e6cee9b5b1c58 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 14 Dec 2009 17:59:16 -0800 Subject: ksm: three remove_rmap_item_from_tree cleanups 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 Cc: Izik Eidus Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/ksm.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) (limited to 'mm') diff --git a/mm/ksm.c b/mm/ksm.c index 5575f8628fef..133ea2ca8384 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -453,6 +453,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item) } 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(struct rmap_item *rmap_item) 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 page *page, struct rmap_item *rmap_item) 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 page *page, struct rmap_item *rmap_item) * 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_item(struct mm_slot *mm_slot, 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; -- cgit v1.2.3