Bill, does this look like the correct fix for the problem to you? If
so, please apply Andrew.
set_page_dirty() will not cope with being handed a page * which is
part of a compound page, but not the master page in that compound
page. This case can occur via access_process_vm() if you attempt to
write to another process's hugepage memory area using ptrace()
(causing an oops or hang).
This patch fixes the bug by first resolving the page * to the compound
page's master page.
Signed-off-by: David Gibson <[email protected]>
Index: working-2.6/mm/page-writeback.c
===================================================================
--- working-2.6.orig/mm/page-writeback.c 2005-11-29 15:51:11.000000000 +1100
+++ working-2.6/mm/page-writeback.c 2005-11-29 15:52:09.000000000 +1100
@@ -660,7 +660,12 @@ EXPORT_SYMBOL(redirty_page_for_writepage
*/
int fastcall set_page_dirty(struct page *page)
{
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping;
+
+ if (unlikely(PageCompound(page)))
+ page = (struct page *)page_private(page);
+
+ mapping = page_mapping(page);
if (likely(mapping)) {
int (*spd)(struct page *) = mapping->a_ops->set_page_dirty;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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