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author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-12-14 17:59:16 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-15 08:53:18 -0800 |
commit | 93d17715a5b960d34220f2edba3e6cee9b5b1c58 (patch) | |
tree | 9ab08ff4169464bf5b8d86c8082296fd6e3d069b /mm/ksm.c | |
parent | 338fde90930eaa02f6f394daa23d35a410af5852 (diff) | |
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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 <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/ksm.c')
-rw-r--r-- | mm/ksm.c | 17 |
1 files changed, 6 insertions, 11 deletions
@@ -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; |