From: Christoph Lameter The radix tree rcu code runs into trouble when we use radix_tree_lookup slot and use the slot to update the page reference. Use radix_tree_lookup instead and update the page reference via radix_tree_delete and radix_tree_insert. Signed-off-by: Christoph Lameter Cc: Nick Piggin Signed-off-by: Andrew Morton --- mm/migrate.c | 14 +++++++++----- 1 files changed, 9 insertions(+), 5 deletions(-) diff -puN mm/migrate.c~page-migration-replace-radix_tree_lookup_slot-with-radix_tree_lockup mm/migrate.c --- a/mm/migrate.c~page-migration-replace-radix_tree_lookup_slot-with-radix_tree_lockup +++ a/mm/migrate.c @@ -294,7 +294,8 @@ out: static int migrate_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page) { - struct page **radix_pointer; + struct page *current_page; + long index; if (!mapping) { /* Anonymous page */ @@ -305,12 +306,14 @@ static int migrate_page_move_mapping(str write_lock_irq(&mapping->tree_lock); - radix_pointer = (struct page **)radix_tree_lookup_slot( + index = page_index(page); + + current_page = (struct page *)radix_tree_lookup( &mapping->page_tree, - page_index(page)); + index); if (page_count(page) != 2 + !!PagePrivate(page) || - radix_tree_deref_slot(radix_pointer) != page) { + current_page != page) { write_unlock_irq(&mapping->tree_lock); return -EAGAIN; } @@ -326,7 +329,8 @@ static int migrate_page_move_mapping(str } #endif - radix_tree_replace_slot(radix_pointer, newpage); + radix_tree_delete(&mapping->page_tree, index); + radix_tree_insert(&mapping->page_tree, index, newpage); __put_page(page); write_unlock_irq(&mapping->tree_lock); _