[PATCH] page migration cleanup: drop nr_refs in remove_references()
Drop nr_refs parameter from migrate_page_remove_references() The nr_refs parameter is not really useful since the number of remaining references is always 1 for anonymous pages without a mapping 2 for pages with a mapping 3 for pages with a mapping and PagePrivate set. Remove the early check for the number of references since we are checking page_mapcount() earlier. Ultimately only the refcount matters after the tree_lock has been obtained. Signed-off-by: Christoph Lameter <clameter@sgi.coim> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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21
mm/migrate.c
21
mm/migrate.c
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@ -168,19 +168,19 @@ retry:
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/*
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/*
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* Remove references for a page and establish the new page with the correct
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* Remove references for a page and establish the new page with the correct
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* basic settings to be able to stop accesses to the page.
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* basic settings to be able to stop accesses to the page.
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*
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* The number of remaining references must be:
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* 1 for anonymous pages without a mapping
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* 2 for pages with a mapping
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* 3 for pages with a mapping and PagePrivate set.
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*/
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*/
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static int migrate_page_remove_references(struct page *newpage,
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static int migrate_page_remove_references(struct page *newpage,
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struct page *page, int nr_refs)
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struct page *page)
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{
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{
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struct address_space *mapping = page_mapping(page);
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struct address_space *mapping = page_mapping(page);
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struct page **radix_pointer;
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struct page **radix_pointer;
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/*
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if (!mapping)
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* Avoid doing any of the following work if the page count
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* indicates that the page is in use or truncate has removed
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* the page.
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*/
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if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
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return -EAGAIN;
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return -EAGAIN;
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/*
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/*
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@ -218,7 +218,8 @@ static int migrate_page_remove_references(struct page *newpage,
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&mapping->page_tree,
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&mapping->page_tree,
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page_index(page));
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page_index(page));
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if (!page_mapping(page) || page_count(page) != nr_refs ||
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if (!page_mapping(page) ||
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page_count(page) != 2 + !!PagePrivate(page) ||
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*radix_pointer != page) {
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*radix_pointer != page) {
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write_unlock_irq(&mapping->tree_lock);
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write_unlock_irq(&mapping->tree_lock);
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return -EAGAIN;
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return -EAGAIN;
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@ -309,7 +310,7 @@ int migrate_page(struct page *newpage, struct page *page)
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BUG_ON(PageWriteback(page)); /* Writeback must be complete */
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BUG_ON(PageWriteback(page)); /* Writeback must be complete */
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rc = migrate_page_remove_references(newpage, page, 2);
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rc = migrate_page_remove_references(newpage, page);
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if (rc)
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if (rc)
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return rc;
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return rc;
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@ -348,7 +349,7 @@ int buffer_migrate_page(struct page *newpage, struct page *page)
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head = page_buffers(page);
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head = page_buffers(page);
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rc = migrate_page_remove_references(newpage, page, 3);
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rc = migrate_page_remove_references(newpage, page);
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if (rc)
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if (rc)
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return rc;
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return rc;
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