xen: fix scrub_page()
Impact: fix guest kernel crash with CONFIG_XEN_SCRUB_PAGES=y
Jens noticed that scrub_page() has a buggy unmap of the wrong
thing. (virtual address instead of page)
Linus pointed out that the whole scrub_page() code is an unnecessary
reimplementation of clear_highpage() to begin with.
Just use clear_highpage() rather than reimplementing it poorly.
Reported-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index a0fb5ea..526c191 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -122,14 +122,7 @@
static void scrub_page(struct page *page)
{
#ifdef CONFIG_XEN_SCRUB_PAGES
- if (PageHighMem(page)) {
- void *v = kmap(page);
- clear_page(v);
- kunmap(v);
- } else {
- void *v = page_address(page);
- clear_page(v);
- }
+ clear_highpage(page);
#endif
}