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[PATCH] page migration: fail if page is in a vma flagged VM_LOCKED

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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 <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2006-03-14 19:50:19 -08:00 committed by Linus Torvalds
parent e843e280cb
commit 4983da07f1
2 changed files with 16 additions and 8 deletions
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6
fs/buffer.c
View file

@ -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 {

18
mm/vmscan.c
View file

@ -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);