On Thu 12-01-12 18:33:23, KAMEZAWA Hiroyuki wrote:
[...]
> > From 04f74e6f0ebf28f61650d63f8884e8855fb21b55 Mon Sep 17 00:00:00 2001
> > From: Michal Hocko <mhocko@xxxxxxx>
> > Date: Thu, 12 Jan 2012 10:19:04 +0100
> > Subject: [PATCH] mm: __count_immobile_pages make sure the node is online
> >
> > page_zone requires to have an online node otherwise we are accessing
> > NULL NODE_DATA. This is not an issue at the moment because node_zones
> > are located at the structure beginning but this might change in the
> > future so better be careful about that.
> >
> > Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > ---
> > mm/page_alloc.c | 11 +++++++++--
> > 1 files changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 485be89..c6fb8ea 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -5607,14 +5607,21 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count)
> >
> > bool is_pageblock_removable_nolock(struct page *page)
> > {
> > - struct zone *zone = page_zone(page);
> > - unsigned long pfn = page_to_pfn(page);
> > + struct zone *zone;
> > + unsigned long pfn;
> >
> > /*
> > * We have to be careful here because we are iterating over memory
> > * sections which are not zone aware so we might end up outside of
> > * the zone but still within the section.
> > + * We have to take care about the node as well. If the node is offline
> > + * its NODE_DATA will be NULL - see page_zone.
> > */
> > + if (!node_online(page_to_nid(page)))
> > + return false;
> > +
> > + zone = page_zone(page);
> > + pfn = page_to_pfn(page);
> > if (!zone || zone->zone_start_pfn > pfn ||
> > zone->zone_start_pfn + zone->spanned_pages <= pfn)
> > return false;
>
> !zone check can be removed because of node_online() check.
Yes you are right. Fixed bellow:
---
>From 39de8df13532150fc4518dad0cb3f6fd88745b8a Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@xxxxxxx>
Date: Thu, 12 Jan 2012 10:19:04 +0100
Subject: [PATCH] mm: __count_immobile_pages make sure the node is online
page_zone requires to have an online node otherwise we are accessing
NULL NODE_DATA. This is not an issue at the moment because node_zones
are located at the structure beginning but this might change in the
future so better be careful about that.
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
mm/page_alloc.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 485be89..b09e8c2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5607,15 +5607,22 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count)
bool is_pageblock_removable_nolock(struct page *page)
{
- struct zone *zone = page_zone(page);
- unsigned long pfn = page_to_pfn(page);
+ struct zone *zone;
+ unsigned long pfn;
/*
* We have to be careful here because we are iterating over memory
* sections which are not zone aware so we might end up outside of
* the zone but still within the section.
+ * We have to take care about the node as well. If the node is offline
+ * its NODE_DATA will be NULL - see page_zone.
*/
- if (!zone || zone->zone_start_pfn > pfn ||
+ if (!node_online(page_to_nid(page)))
+ return false;
+
+ zone = page_zone(page);
+ pfn = page_to_pfn(page);
+ if (zone->zone_start_pfn > pfn ||
zone->zone_start_pfn + zone->spanned_pages <= pfn)
return false;
--
1.7.7.3
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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