On (14/03/07 09:11), Bjorn Helgaas didst pronounce:
> On Wednesday 14 March 2007 03:44, Mel Gorman wrote:
> > Please try the following patch from Yasunori Goto.
> > ...
> > --- current_test.orig/mm/page_alloc.c 2007-03-08 15:44:10.000000000
> > +0900
> > +++ current_test/mm/page_alloc.c 2007-03-08 16:17:29.000000000 +0900
> > @@ -707,7 +707,7 @@ int move_freepages(struct zone *zone,
> > unsigned long order;
> > int blocks_moved = 0;
> >
> > - BUG_ON(page_zone(start_page) != page_zone(end_page));
> > + BUG_ON(page_zone(start_page) != page_zone(end_page - 1));
> >
>
> I should have mentioned that I already tried this patch. The
> oops still occurs, although now it's when loading the value
> pointed to by "end_page - 1" instead of "end_page".
Ok. This looks like another case of HOLES_IN_ZONE hilarity with page_zone().
As I take a new look at the BUG_ON check in move_freepages(), it isn't even
necessary as move_freepages_block() already checks the zone boundaries. At a
later date when the code has survived a while without new bug reports, I'll
submit a patch that simply deletes this check because it should be redundant.
Just in case, I'd like to preserve the check in the non-HOLES_IN_ZONE
case for now.
Can you try this patch please? It should apply on top of Yasunori Goto's
patch.
Signed-off-by: Mel Gorman <[EMAIL PROTECTED]>
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff
linux-2.6.21-rc3-mm2-goto/mm/page_alloc.c
linux-2.6.21-rc3-mm2-bjorn_testfix/mm/page_alloc.c
--- linux-2.6.21-rc3-mm2-goto/mm/page_alloc.c 2007-03-14 16:07:23.000000000
+0000
+++ linux-2.6.21-rc3-mm2-bjorn_testfix/mm/page_alloc.c 2007-03-14
16:01:00.000000000 +0000
@@ -707,7 +707,15 @@ int move_freepages(struct zone *zone,
unsigned long order;
int blocks_moved = 0;
+#ifndef CONFIG_HOLES_IN_ZONE
+ /*
+ * page_zone is not safe to call in this context when
+ * CONFIG_HOLES_IN_ZONE is set but this bug check is
+ * redundant anyway as we check zone boundaries in
+ * move_freepages_block()
+ */
BUG_ON(page_zone(start_page) != page_zone(end_page - 1));
+#endif
for (page = start_page; page < end_page;) {
if (!PageBuddy(page)) {
-
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