forked from luck/tmp_suning_uos_patched
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>
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parent
338fde9093
commit
93d17715a5
19
mm/ksm.c
19
mm/ksm.c
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@ -453,6 +453,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
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}
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rmap_item->next = NULL;
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rmap_item->address &= PAGE_MASK;
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} else if (rmap_item->address & NODE_FLAG) {
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unsigned char age;
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@ -467,10 +468,10 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
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BUG_ON(age > 1);
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if (!age)
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rb_erase(&rmap_item->node, &root_unstable_tree);
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ksm_pages_unshared--;
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}
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rmap_item->address &= PAGE_MASK;
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ksm_pages_unshared--;
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rmap_item->address &= PAGE_MASK;
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}
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cond_resched(); /* we're called from many long loops */
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}
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@ -1086,8 +1087,7 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
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unsigned int checksum;
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int err;
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if (in_stable_tree(rmap_item))
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remove_rmap_item_from_tree(rmap_item);
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remove_rmap_item_from_tree(rmap_item);
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/* We first start with searching the page inside the stable tree */
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tree_rmap_item = stable_tree_search(page, page2, rmap_item);
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@ -1143,9 +1143,7 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
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* tree, and insert it instead as new node in the stable tree.
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*/
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if (!err) {
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rb_erase(&tree_rmap_item->node, &root_unstable_tree);
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tree_rmap_item->address &= ~NODE_FLAG;
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ksm_pages_unshared--;
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remove_rmap_item_from_tree(tree_rmap_item);
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/*
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* If we fail to insert the page into the stable tree,
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@ -1174,11 +1172,8 @@ static struct rmap_item *get_next_rmap_item(struct mm_slot *mm_slot,
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while (cur != &mm_slot->rmap_list) {
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rmap_item = list_entry(cur, struct rmap_item, link);
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if ((rmap_item->address & PAGE_MASK) == addr) {
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if (!in_stable_tree(rmap_item))
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remove_rmap_item_from_tree(rmap_item);
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if ((rmap_item->address & PAGE_MASK) == addr)
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return rmap_item;
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}
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if (rmap_item->address > addr)
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break;
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cur = cur->next;
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