From 4983da07f1e2e8dc81cb9d640fbf35b899cdbdf2 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 14 Mar 2006 19:50:19 -0800 Subject: [PATCH] [PATCH] page migration: fail if page is in a vma flagged VM_LOCKED page migration currently simply retries a couple of times if try_to_unmap() fails without inspecting the return code. However, SWAP_FAIL indicates that the page is in a vma that has the VM_LOCKED flag set (if ignore_refs ==1). We can check for that return code and avoid retrying the migration. migrate_page_remove_references() now needs to return a reason why the failure occured. So switch migrate_page_remove_references to use -Exx style error messages. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/buffer.c | 6 ++++-- mm/vmscan.c | 18 ++++++++++++------ 2 files changed, 16 insertions(+), 8 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 62cfd17dc5fe..a9b399402007 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -3060,6 +3060,7 @@ int buffer_migrate_page(struct page *newpage, struct page *page) { struct address_space *mapping = page->mapping; struct buffer_head *bh, *head; + int rc; if (!mapping) return -EAGAIN; @@ -3069,8 +3070,9 @@ int buffer_migrate_page(struct page *newpage, struct page *page) head = page_buffers(page); - if (migrate_page_remove_references(newpage, page, 3)) - return -EAGAIN; + rc = migrate_page_remove_references(newpage, page, 3); + if (rc) + return rc; bh = head; do { diff --git a/mm/vmscan.c b/mm/vmscan.c index 7ccf763bb30b..4fe7e3aa02e2 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -700,7 +700,7 @@ int migrate_page_remove_references(struct page *newpage, * the page. */ if (!mapping || page_mapcount(page) + nr_refs != page_count(page)) - return 1; + return -EAGAIN; /* * Establish swap ptes for anonymous pages or destroy pte @@ -721,13 +721,15 @@ int migrate_page_remove_references(struct page *newpage, * If the page was not migrated then the PageSwapCache bit * is still set and the operation may continue. */ - try_to_unmap(page, 1); + if (try_to_unmap(page, 1) == SWAP_FAIL) + /* A vma has VM_LOCKED set -> Permanent failure */ + return -EPERM; /* * Give up if we were unable to remove all mappings. */ if (page_mapcount(page)) - return 1; + return -EAGAIN; write_lock_irq(&mapping->tree_lock); @@ -738,7 +740,7 @@ int migrate_page_remove_references(struct page *newpage, if (!page_mapping(page) || page_count(page) != nr_refs || *radix_pointer != page) { write_unlock_irq(&mapping->tree_lock); - return 1; + return -EAGAIN; } /* @@ -813,10 +815,14 @@ EXPORT_SYMBOL(migrate_page_copy); */ int migrate_page(struct page *newpage, struct page *page) { + int rc; + BUG_ON(PageWriteback(page)); /* Writeback must be complete */ - if (migrate_page_remove_references(newpage, page, 2)) - return -EAGAIN; + rc = migrate_page_remove_references(newpage, page, 2); + + if (rc) + return rc; migrate_page_copy(newpage, page);