On Mon, 17 Nov 2008, Jeremy Fitzhardinge wrote:
Pass the struct page * to kunmap, not the vaddr of the mapping itself.
Pointed out by Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
drivers/xen/balloon.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
===================================================================
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -120,7 +120,7 @@
if (PageHighMem(page)) {
void *v = kmap(page);
clear_page(v);
- kunmap(v);
+ kunmap(page);
} else {
void *v = page_address(page);
clear_page(v);
Well, quite frankly, the whole thing looks like crud.
First off, 'kmap/kunmap' work on regular pages too. So if you're highmem aware, you should just do
void *v = kmap(page);
clear_page(v);
kunmap(page);
and be done with it.
Secondly, we actually have a function called "clear_highpage()" that does this, except it uses kmap_atomic(page, KM_USER0). Which is _probably better anyway, but I didn't check if there is some magical reason why it wouldn't work.