On 08/01/2013 02:18 AM, Xishi Qiu wrote:
__offline_pages()
start_isolate_page_range()
set_migratetype_isolate()
set_pageblock_migratetype() -> this pageblock will be marked as
MIGRATE_ISOLATE
move_freepages_block() -> pages in PageBuddy will be moved into
MIGRATE_ISOLATE list
drain_all_pages() -> drain PCP
free_pcppages_bulk()
mt = get_freepage_migratetype(page); -> PCP's migratetype is
not MIGRATE_ISOLATE
__free_one_page(page, zone, 0, mt); -> so PCP will not be freed
into into MIGRATE_ISOLATE list
In this case, the PCP may be allocated again, because they are not in
PageBuddy's MIGRATE_ISOLATE list. This will cause offline_pages failed.
Signed-off-by: Xishi Qiu <qiuxi...@huawei.com>
---
mm/page_alloc.c | 10 ++++++----
mm/page_isolation.c | 15 ++++++++++++++-
2 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b100255..d873471 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -965,11 +965,13 @@ int move_freepages(struct zone *zone,
}
order = page_order(page);
- list_move(&page->lru,
- &zone->free_area[order].free_list[migratetype]);
- set_freepage_migratetype(page, migratetype);
+ if (get_freepage_migratetype(page) != migratetype) {
+ list_move(&page->lru,
+ &zone->free_area[order].free_list[migratetype]);
+ set_freepage_migratetype(page, migratetype);
+ pages_moved += 1 << order;
+ }
page += 1 << order;
- pages_moved += 1 << order;
So this looks like it changes the return from move_freepages() to be the
"pages moved" from "the pages now belonging to the passed migrate type".
The user of move_freepages_block()'s return value (and thus the return
value of move_freepages()) in mm/page_alloc.c expects that it is the
original meaning. The users in page_isolation.c expect it is the new
meaning. Those need to be reconciled.
}
return pages_moved;
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 383bdbb..ba1afc9 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -65,8 +65,21 @@ out:
}
spin_unlock_irqrestore(&zone->lock, flags);
- if (!ret)
+
+ if (!ret) {
drain_all_pages();
+ /*
+ * When drain_all_pages() frees cached pages into the buddy
+ * system, it uses the stale migratetype cached in the
+ * page->index field, so try to move free pages to ISOLATE
+ * list again.
+ */
+ spin_lock_irqsave(&zone->lock, flags);
+ nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
+ __mod_zone_freepage_state(zone, -nr_pages, migratetype);
+ spin_unlock_irqrestore(&zone->lock, flags);
+ }
+
Could we teach drain_all_pages() to use the right migrate type instead
(or add something similar that does)? (pages could be reallocated
between the drain_all_pages() and move_freepages_block()).
return ret;
}
--
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