* [merged] vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full.patch removed from -mm tree
@ 2009-06-17 18:36 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2009-06-17 18:36 UTC (permalink / raw)
To: mel, cl, fengguang.wu, kosaki.motohiro, riel, stable, mm-commits
The patch titled
vmscan: do not unconditionally treat zones that fail zone_reclaim() as full
has been removed from the -mm tree. Its filename was
vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: vmscan: do not unconditionally treat zones that fail zone_reclaim() as full
From: Mel Gorman <mel@csn.ul.ie>
On NUMA machines, the administrator can configure zone_reclaim_mode that
is a more targetted form of direct reclaim. On machines with large NUMA
distances for example, a zone_reclaim_mode defaults to 1 meaning that
clean unmapped pages will be reclaimed if the zone watermarks are not
being met. The problem is that zone_reclaim() failing at all means the
zone gets marked full.
This can cause situations where a zone is usable, but is being skipped
because it has been considered full. Take a situation where a large tmpfs
mount is occuping a large percentage of memory overall. The pages do not
get cleaned or reclaimed by zone_reclaim(), but the zone gets marked full
and the zonelist cache considers them not worth trying in the future.
This patch makes zone_reclaim() return more fine-grained information about
what occured when zone_reclaim() failued. The zone only gets marked full
if it really is unreclaimable. If it's a case that the scan did not occur
or if enough pages were not reclaimed with the limited reclaim_mode, then
the zone is simply skipped.
There is a side-effect to this patch. Currently, if zone_reclaim()
successfully reclaimed SWAP_CLUSTER_MAX, an allocation attempt would go
ahead. With this patch applied, zone watermarks are rechecked after
zone_reclaim() does some work.
This bug was introduced by commit 9276b1bc96a132f4068fdee00983c532f43d3a26
("memory page_alloc zonelist caching speedup") way back in 2.6.19 when the
zonelist_cache was introduced. It was not intended that zone_reclaim()
aggressively consider the zone to be full when it failed as full direct
reclaim can still be an option. Due to the age of the bug, it should be
considered a -stable candidate.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/internal.h | 4 ++++
mm/page_alloc.c | 26 ++++++++++++++++++++++----
mm/vmscan.c | 11 ++++++-----
3 files changed, 32 insertions(+), 9 deletions(-)
diff -puN mm/internal.h~vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full mm/internal.h
--- a/mm/internal.h~vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full
+++ a/mm/internal.h
@@ -259,4 +259,8 @@ int __get_user_pages(struct task_struct
unsigned long start, int len, int flags,
struct page **pages, struct vm_area_struct **vmas);
+#define ZONE_RECLAIM_NOSCAN -2
+#define ZONE_RECLAIM_FULL -1
+#define ZONE_RECLAIM_SOME 0
+#define ZONE_RECLAIM_SUCCESS 1
#endif
diff -puN mm/page_alloc.c~vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full mm/page_alloc.c
--- a/mm/page_alloc.c~vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full
+++ a/mm/page_alloc.c
@@ -1462,15 +1462,33 @@ zonelist_scan:
BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
unsigned long mark;
+ int ret;
+
mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
- if (!zone_watermark_ok(zone, order, mark,
- classzone_idx, alloc_flags)) {
- if (!zone_reclaim_mode ||
- !zone_reclaim(zone, gfp_mask, order))
+ if (zone_watermark_ok(zone, order, mark,
+ classzone_idx, alloc_flags))
+ goto try_this_zone;
+
+ if (zone_reclaim_mode == 0)
+ goto this_zone_full;
+
+ ret = zone_reclaim(zone, gfp_mask, order);
+ switch (ret) {
+ case ZONE_RECLAIM_NOSCAN:
+ /* did not scan */
+ goto try_next_zone;
+ case ZONE_RECLAIM_FULL:
+ /* scanned but unreclaimable */
+ goto this_zone_full;
+ default:
+ /* did we reclaim enough */
+ if (!zone_watermark_ok(zone, order, mark,
+ classzone_idx, alloc_flags))
goto this_zone_full;
}
}
+try_this_zone:
page = buffered_rmqueue(preferred_zone, zone, order,
gfp_mask, migratetype);
if (page)
diff -puN mm/vmscan.c~vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full mm/vmscan.c
--- a/mm/vmscan.c~vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full
+++ a/mm/vmscan.c
@@ -2492,16 +2492,16 @@ int zone_reclaim(struct zone *zone, gfp_
*/
if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
- return 0;
+ return ZONE_RECLAIM_FULL;
if (zone_is_all_unreclaimable(zone))
- return 0;
+ return ZONE_RECLAIM_FULL;
/*
* Do not scan if the allocation should not be delayed.
*/
if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
- return 0;
+ return ZONE_RECLAIM_NOSCAN;
/*
* Only run zone reclaim on the local zone or on zones that do not
@@ -2511,10 +2511,11 @@ int zone_reclaim(struct zone *zone, gfp_
*/
node_id = zone_to_nid(zone);
if (node_state(node_id, N_CPU) && node_id != numa_node_id())
- return 0;
+ return ZONE_RECLAIM_NOSCAN;
if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
- return 0;
+ return ZONE_RECLAIM_NOSCAN;
+
ret = __zone_reclaim(zone, gfp_mask, order);
zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
_
Patches currently in -mm which might be from mel@csn.ul.ie are
origin.patch
linux-next.patch
page_alloc-oops-when-setting-percpu_pagelist_fraction.patch
memcg-fix-lru-rotation-in-isolate_pages.patch
add-debugging-aid-for-memory-initialisation-problems.patch
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2009-06-17 18:36 [merged] vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full.patch removed from -mm tree akpm
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