From e8788c0cce63e0cc8689a123d1ce0af1e28cd583 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 28 Feb 2006 16:59:16 -0800 Subject: [PATCH] [PATCH] remove_from_swap: fix locking remove_from_swap() currently attempts to use page_lock_anon_vma to obtain an anon_vma lock. That is not working since the page may have been remapped via swap ptes in order to move the page. However, do_migrate_pages() obtain the mmap_sem lock and therefore there is a guarantee that the anonymous vma will not vanish from under us. There is therefore no need to use page_lock_anon_vma. Signed-off-by: Christoph Lameter Acked-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index df2c41c..d8ce5ff 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -212,25 +212,33 @@ out: * through real pte's pointing to valid pages and then releasing * the page from the swap cache. * - * Must hold page lock on page. + * Must hold page lock on page and mmap_sem of one vma that contains + * the page. */ void remove_from_swap(struct page *page) { struct anon_vma *anon_vma; struct vm_area_struct *vma; + unsigned long mapping; - if (!PageAnon(page) || !PageSwapCache(page)) + if (!PageSwapCache(page)) return; - anon_vma = page_lock_anon_vma(page); - if (!anon_vma) + mapping = (unsigned long)page->mapping; + + if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) return; + /* + * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. + */ + anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); + spin_lock(&anon_vma->lock); + list_for_each_entry(vma, &anon_vma->head, anon_vma_node) remove_vma_swap(vma, page); spin_unlock(&anon_vma->lock); - delete_from_swap_cache(page); } EXPORT_SYMBOL(remove_from_swap); -- 2.7.4