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[PATCH] remove_from_swap: fix locking

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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 <clameter@sgi.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2006-02-28 16:59:16 -08:00 committed by Linus Torvalds
parent 6af6aab34a
commit e8788c0cce
1 changed files with 13 additions and 5 deletions
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18
mm/rmap.c
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@ -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);