Subject: + mm-__rmqueue_fallback-should-respect-pageblock-type.patch added to -mm tree
To: kosaki.motohiro@xxxxxxxxxxxxxx,mgorman@xxxxxxx,mina86@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 31 Oct 2013 12:08:04 -0700
The patch titled
Subject: mm: __rmqueue_fallback() should respect pageblock type
has been added to the -mm tree. Its filename is
mm-__rmqueue_fallback-should-respect-pageblock-type.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-__rmqueue_fallback-should-respect-pageblock-type.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-__rmqueue_fallback-should-respect-pageblock-type.patch
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------------------------------------------------------
From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Subject: mm: __rmqueue_fallback() should respect pageblock type
When __rmqueue_fallback() doesn't find a free block with the required size
it splits a larger page and puts the rest of the page onto the free list.
But it has one serious mistake. When putting back, __rmqueue_fallback()
always use start_migratetype if type is not CMA. However,
__rmqueue_fallback() is only called when all of the start_migratetype
queue is empty. That said, __rmqueue_fallback always puts back memory to
the wrong queue except try_to_steal_freepages() changed pageblock type
(i.e. requested size is smaller than half of page block). The end result
is that the antifragmentation framework increases fragmenation instead of
decreasing it.
Mel's original anti fragmentation does the right thing. But commit
47118af076 ("mm: mmzone: MIGRATE_CMA migration type added") broke it.
This patch restores sane and old behavior. And also it remvoe an
incorrect comment which introduced at commit fef903efcf (mm/page_alloc.c:
restructure free-page stealing code and fix a bug).
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
diff -puN mm/page_alloc.c~mm-__rmqueue_fallback-should-respect-pageblock-type mm/page_alloc.c
--- a/mm/page_alloc.c~mm-__rmqueue_fallback-should-respect-pageblock-type
+++ a/mm/page_alloc.c
@@ -1027,6 +1027,10 @@ static int try_to_steal_freepages(struct
{
int current_order = page_order(page);
+ /*
+ * When borrowing from MIGRATE_CMA, we need to release the excess
+ * buddy pages to CMA itself.
+ */
if (is_migrate_cma(fallback_type))
return fallback_type;
@@ -1091,17 +1095,7 @@ __rmqueue_fallback(struct zone *zone, in
list_del(&page->lru);
rmv_page_order(page);
- /*
- * Borrow the excess buddy pages as well, irrespective
- * of whether we stole freepages, or took ownership of
- * the pageblock or not.
- *
- * Exception: When borrowing from MIGRATE_CMA, release
- * the excess buddy pages to CMA itself.
- */
- expand(zone, page, order, current_order, area,
- is_migrate_cma(migratetype)
- ? migratetype : start_migratetype);
+ expand(zone, page, order, current_order, area, new_type);
trace_mm_page_alloc_extfrag(page, order, current_order,
start_migratetype, migratetype, new_type);
_
Patches currently in -mm which might be from kosaki.motohiro@xxxxxxxxxxxxxx are
mm-mempolicy-make-mpol_to_str-robust-and-always-succeed.patch
mm-vmalloc-dont-set-area-caller-twice.patch
mm-vmalloc-fix-show-vmap_area-information-race-with-vmap_area-tear-down.patch
mm-vmalloc-revert-mm-vmallocc-check-vm_uninitialized-flag-in-s_show-instead-of-show_numa_info.patch
revert-mm-vmallocc-emit-the-failure-message-before-return.patch
mm-mempolicy-use-numa_no_node.patch
mm-fix-page_group_by_mobility_disabled-breakage.patch
mm-get-rid-of-unnecessary-overhead-of-trace_mm_page_alloc_extfrag.patch
mm-__rmqueue_fallback-should-respect-pageblock-type.patch
linux-next.patch
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