Commit Graph

725 Commits

Author SHA1 Message Date
David Rientjes 6b187d0260 mm, numa: avoid setting zone_reclaim_mode unless a node is sufficiently distant
Commit 957f822a0a ("mm, numa: reclaim from all nodes within reclaim
distance") caused zone_reclaim_mode to be set for all systems where two
nodes are within RECLAIM_DISTANCE of each other.  This is the opposite
of what we actually want: zone_reclaim_mode should be set if two nodes
are sufficiently distant.

Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Julian Wollrath <jwollrath@web.de>
Tested-by: Julian Wollrath <jwollrath@web.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Patrik Kullman <patrik.kullman@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-25 14:37:53 -07:00
Bob Liu 86a595f961 mm/page_alloc.c:alloc_contig_range(): return early for err path
If start_isolate_page_range() failed, unset_migratetype_isolate() has been
done inside it.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Ni zhan Chen <nizhan.chen@gmail.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-25 14:37:52 -07:00
Minchan Kim beb51eaa88 cma: decrease cc.nr_migratepages after reclaiming pagelist
reclaim_clean_pages_from_list() reclaims clean pages before migration so
cc.nr_migratepages should be updated.  Currently, there is no problem but
it can be wrong if we try to use the value in future.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:23:01 +09:00
Minchan Kim e46a28790e CMA: migrate mlocked pages
Presently CMA cannot migrate mlocked pages so it ends up failing to allocate
contiguous memory space.

This patch makes mlocked pages be migrated out.  Of course, it can affect
realtime processes but in CMA usecase, contiguous memory allocation failing
is far worse than access latency to an mlocked page being variable while
CMA is running.  If someone wants to make the system realtime, he shouldn't
enable CMA because stalls can still happen at random times.

[akpm@linux-foundation.org: tweak comment text, per Mel]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:23:00 +09:00
Minchan Kim 5a88381384 memory-hotplug: fix zone stat mismatch
During memory-hotplug, I found NR_ISOLATED_[ANON|FILE] are increasing,
causing the kernel to hang.  When the system doesn't have enough free
pages, it enters reclaim but never reclaim any pages due to
too_many_isolated()==true and loops forever.

The cause is that when we do memory-hotadd after memory-remove,
__zone_pcp_update() clears a zone's ZONE_STAT_ITEMS in setup_pageset()
although the vm_stat_diff of all CPUs still have values.

In addtion, when we offline all pages of the zone, we reset them in
zone_pcp_reset without draining so we loss some zone stat item.

Reviewed-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:59 +09:00
David Rientjes 957f822a0a mm, numa: reclaim from all nodes within reclaim distance
RECLAIM_DISTANCE represents the distance between nodes at which it is
deemed too costly to allocate from; it's preferred to try to reclaim from
a local zone before falling back to allocating on a remote node with such
a distance.

To do this, zone_reclaim_mode is set if the distance between any two
nodes on the system is greather than this distance.  This, however, ends
up causing the page allocator to reclaim from every zone regardless of
its affinity.

What we really want is to reclaim only from zones that are closer than
RECLAIM_DISTANCE.  This patch adds a nodemask to each node that
represents the set of nodes that are within this distance.  During the
zone iteration, if the bit for a zone's node is set for the local node,
then reclaim is attempted; otherwise, the zone is skipped.

[akpm@linux-foundation.org: fix CONFIG_NUMA=n build]
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:56 +09:00
Hugh Dickins a0c5e813f0 mm: remove free_page_mlock
We should not be seeing non-0 unevictable_pgs_mlockfreed any longer.  So
remove free_page_mlock() from the page freeing paths: __PG_MLOCKED is
already in PAGE_FLAGS_CHECK_AT_FREE, so free_pages_check() will now be
checking it, reporting "BUG: Bad page state" if it's ever found set.
Comment UNEVICTABLE_MLOCKFREED and unevictable_pgs_mlockfreed always 0.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:56 +09:00
Jianguo Wu 7f1290f2f2 mm: fix-up zone present pages
I think zone->present_pages indicates pages that buddy system can management,
it should be:

	zone->present_pages = spanned pages - absent pages - bootmem pages,

but is now:
	zone->present_pages = spanned pages - absent pages - memmap pages.

spanned pages: total size, including holes.
absent pages: holes.
bootmem pages: pages used in system boot, managed by bootmem allocator.
memmap pages: pages used by page structs.

This may cause zone->present_pages less than it should be.  For example,
numa node 1 has ZONE_NORMAL and ZONE_MOVABLE, it's memmap and other
bootmem will be allocated from ZONE_MOVABLE, so ZONE_NORMAL's
present_pages should be spanned pages - absent pages, but now it also
minus memmap pages(free_area_init_core), which are actually allocated from
ZONE_MOVABLE.  When offlining all memory of a zone, this will cause
zone->present_pages less than 0, because present_pages is unsigned long
type, it is actually a very large integer, it indirectly caused
zone->watermark[WMARK_MIN] becomes a large
integer(setup_per_zone_wmarks()), than cause totalreserve_pages become a
large integer(calculate_totalreserve_pages()), and finally cause memory
allocating failure when fork process(__vm_enough_memory()).

[root@localhost ~]# dmesg
-bash: fork: Cannot allocate memory

I think the bug described in

  http://marc.info/?l=linux-mm&m=134502182714186&w=2

is also caused by wrong zone present pages.

This patch intends to fix-up zone->present_pages when memory are freed to
buddy system on x86_64 and IA64 platforms.

Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Reported-by: Petr Tesarik <ptesarik@suse.cz>
Tested-by: Petr Tesarik <ptesarik@suse.cz>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:54 +09:00
Minchan Kim 723a0644a7 mm/page_alloc: refactor out __alloc_contig_migrate_alloc()
__alloc_contig_migrate_alloc() can be used by memory-hotplug so refactor
it out (move + rename as a common name) into page_isolation.c.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:52 +09:00
Mel Gorman 62997027ca mm: compaction: clear PG_migrate_skip based on compaction and reclaim activity
Compaction caches if a pageblock was scanned and no pages were isolated so
that the pageblocks can be skipped in the future to reduce scanning.  This
information is not cleared by the page allocator based on activity due to
the impact it would have to the page allocator fast paths.  Hence there is
a requirement that something clear the cache or pageblocks will be skipped
forever.  Currently the cache is cleared if there were a number of recent
allocation failures and it has not been cleared within the last 5 seconds.
Time-based decisions like this are terrible as they have no relationship
to VM activity and is basically a big hammer.

Unfortunately, accurate heuristics would add cost to some hot paths so
this patch implements a rough heuristic.  There are two cases where the
cache is cleared.

1. If a !kswapd process completes a compaction cycle (migrate and free
   scanner meet), the zone is marked compact_blockskip_flush. When kswapd
   goes to sleep, it will clear the cache. This is expected to be the
   common case where the cache is cleared. It does not really matter if
   kswapd happens to be asleep or going to sleep when the flag is set as
   it will be woken on the next allocation request.

2. If there have been multiple failures recently and compaction just
   finished being deferred then a process will clear the cache and start a
   full scan.  This situation happens if there are multiple high-order
   allocation requests under heavy memory pressure.

The clearing of the PG_migrate_skip bits and other scans is inherently
racy but the race is harmless.  For allocations that can fail such as THP,
they will simply fail.  For requests that cannot fail, they will retry the
allocation.  Tests indicated that scanning rates were roughly similar to
when the time-based heuristic was used and the allocation success rates
were similar.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:51 +09:00
Mel Gorman bb13ffeb9f mm: compaction: cache if a pageblock was scanned and no pages were isolated
When compaction was implemented it was known that scanning could
potentially be excessive.  The ideal was that a counter be maintained for
each pageblock but maintaining this information would incur a severe
penalty due to a shared writable cache line.  It has reached the point
where the scanning costs are a serious problem, particularly on
long-lived systems where a large process starts and allocates a large
number of THPs at the same time.

Instead of using a shared counter, this patch adds another bit to the
pageblock flags called PG_migrate_skip.  If a pageblock is scanned by
either migrate or free scanner and 0 pages were isolated, the pageblock is
marked to be skipped in the future.  When scanning, this bit is checked
before any scanning takes place and the block skipped if set.

The main difficulty with a patch like this is "when to ignore the cached
information?" If it's ignored too often, the scanning rates will still be
excessive.  If the information is too stale then allocations will fail
that might have otherwise succeeded.  In this patch

o CMA always ignores the information
o If the migrate and free scanner meet then the cached information will
  be discarded if it's at least 5 seconds since the last time the cache
  was discarded
o If there are a large number of allocation failures, discard the cache.

The time-based heuristic is very clumsy but there are few choices for a
better event.  Depending solely on multiple allocation failures still
allows excessive scanning when THP allocations are failing in quick
succession due to memory pressure.  Waiting until memory pressure is
relieved would cause compaction to continually fail instead of using
reclaim/compaction to try allocate the page.  The time-based mechanism is
clumsy but a better option is not obvious.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:50 +09:00
Mel Gorman 753341a4b8 revert "mm: have order > 0 compaction start off where it left"
This reverts commit 7db8889ab0 ("mm: have order > 0 compaction start
off where it left") and commit de74f1cc ("mm: have order > 0 compaction
start near a pageblock with free pages").  These patches were a good
idea and tests confirmed that they massively reduced the amount of
scanning but the implementation is complex and tricky to understand.  A
later patch will cache what pageblocks should be skipped and
reimplements the concept of compact_cached_free_pfn on top for both
migration and free scanners.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:50 +09:00
Wanpeng Li f2d52fe51c mm/memblock: cleanup early_node_map[] related comments
Commit 0ee332c145 ("memblock: Kill early_node_map[]") removed
early_node_map[].  Clean up the comments to comply with that change.

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:47 +09:00
Minchan Kim 435b405c06 memory-hotplug: fix pages missed by race rather than failing
If race between allocation and isolation in memory-hotplug offline
happens, some pages could be in MIGRATE_MOVABLE of free_list although the
pageblock's migratetype of the page is MIGRATE_ISOLATE.

The race could be detected by get_freepage_migratetype in
__test_page_isolated_in_pageblock.  If it is detected, now EBUSY gets
bubbled all the way up and the hotplug operations fails.

But better idea is instead of returning and failing memory-hotremove, move
the free page to the correct list at the time it is detected.  It could
enhance memory-hotremove operation success ratio although the race is
really rare.

Suggested by Mel Gorman.

[akpm@linux-foundation.org: small cleanup]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:46 +09:00
Minchan Kim 95e3441248 mm: remain migratetype in freed page
The page allocator caches the pageblock information in page->private while
it is in the PCP freelists but this is overwritten with the order of the
page when freed to the buddy allocator.  This patch stores the migratetype
of the page in the page->index field so that it is available at all times
when the page remain in free_list.

This patch adds a new call site in __free_pages_ok so it might be overhead
a bit but it's for high order allocation.  So I believe damage isn't hurt.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:45 +09:00
Minchan Kim b12c4ad14e mm: page_alloc: use get_freepage_migratetype() instead of page_private()
The page allocator uses set_page_private and page_private for handling
migratetype when it frees page.  Let's replace them with [set|get]
_freepage_migratetype to make it more clear.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:45 +09:00
Bartlomiej Zolnierkiewicz d95ea5d18e cma: fix watermark checking
* Add ALLOC_CMA alloc flag and pass it to [__]zone_watermark_ok()
  (from Minchan Kim).

* During watermark check decrease available free pages number by
  free CMA pages number if necessary (unmovable allocations cannot
  use pages from CMA areas).

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:45 +09:00
Bartlomiej Zolnierkiewicz d1ce749a0d cma: count free CMA pages
Add NR_FREE_CMA_PAGES counter to be later used for checking watermark in
__zone_watermark_ok().  For simplicity and to avoid #ifdef hell make this
counter always available (not only when CONFIG_CMA=y).

[akpm@linux-foundation.org: use conventional migratetype naming]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:44 +09:00
Bartlomiej Zolnierkiewicz 2139cbe627 cma: fix counting of isolated pages
Isolated free pages shouldn't be accounted to NR_FREE_PAGES counter.  Fix
it by properly decreasing/increasing NR_FREE_PAGES counter in
set_migratetype_isolate()/unset_migratetype_isolate() and removing counter
adjustment for isolated pages from free_one_page() and split_free_page().

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:44 +09:00
Bartlomiej Zolnierkiewicz 770c8aaaf6 mm: fix tracing in free_pcppages_bulk()
page->private gets re-used in __free_one_page() to store page order
(so trace_mm_page_pcpu_drain() may print order instead of migratetype)
thus migratetype value must be cached locally.

Fixes regression introduced in commit a7016235a6 ("mm: fix migratetype
bug which slowed swapping").  This caused incorrect data to be attached
to the mm_page_pcpu_drain trace event.

[akpm@linux-foundation.org: add comment]
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:44 +09:00
Minchan Kim 02c6de8d75 mm: cma: discard clean pages during contiguous allocation instead of migration
Drop clean cache pages instead of migration during alloc_contig_range() to
minimise allocation latency by reducing the amount of migration that is
necessary.  It's useful for CMA because latency of migration is more
important than evicting the background process's working set.  In
addition, as pages are reclaimed then fewer free pages for migration
targets are required so it avoids memory reclaiming to get free pages,
which is a contributory factor to increased latency.

I measured elapsed time of __alloc_contig_migrate_range() which migrates
10M in 40M movable zone in QEMU machine.

Before - 146ms, After - 7ms

[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Mel Gorman <mgorman@suse.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Rik van Riel <riel@redhat.com>
Tested-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:43 +09:00
Mel Gorman 1fb3f8ca0e mm: compaction: capture a suitable high-order page immediately when it is made available
While compaction is migrating pages to free up large contiguous blocks
for allocation it races with other allocation requests that may steal
these blocks or break them up.  This patch alters direct compaction to
capture a suitable free page as soon as it becomes available to reduce
this race.  It uses similar logic to split_free_page() to ensure that
watermarks are still obeyed.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:21 +09:00
Rik van Riel c654345924 mm: remove __GFP_NO_KSWAPD
When transparent huge pages were introduced, memory compaction and swap
storms were an issue, and the kernel had to be careful to not make THP
allocations cause pageout or compaction.

Now that we have working compaction deferral, kswapd is smart enough to
invoke compaction and the quadratic behaviour around isolate_free_pages
has been fixed, it should be safe to remove __GFP_NO_KSWAPD.

[minchan@kernel.org: Comment fix]
[mgorman@suse.de: Avoid direct reclaim for deferred compaction]
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:15 +09:00
Li Haifeng 0ba8f2d593 mm/page_alloc: fix the page address of higher page's buddy calculation
The heuristic method for buddy has been introduced since commit
43506fad21 ("mm/page_alloc.c: simplify calculation of combined index
of adjacent buddy lists").  But the page address of higher page's buddy
was wrongly calculated, which will lead page_is_buddy to fail for ever.
IOW, the heuristic method would be disabled with the wrong page address
of higher page's buddy.

Calculating the page address of higher page's buddy should be based
higher_page with the offset between index of higher page and index of
higher page's buddy.

Signed-off-by: Haifeng Li <omycle@gmail.com>
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: KyongHo Cho <pullip.cho@samsung.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: <stable@vger.kernel.org>	[2.6.38+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-09-17 15:00:38 -07:00
Mel Gorman c67fe3752a mm: compaction: Abort async compaction if locks are contended or taking too long
Jim Schutt reported a problem that pointed at compaction contending
heavily on locks.  The workload is straight-forward and in his own words;

	The systems in question have 24 SAS drives spread across 3 HBAs,
	running 24 Ceph OSD instances, one per drive.  FWIW these servers
	are dual-socket Intel 5675 Xeons w/48 GB memory.  I've got ~160
	Ceph Linux clients doing dd simultaneously to a Ceph file system
	backed by 12 of these servers.

Early in the test everything looks fine

  procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu-------
   r  b       swpd       free       buff      cache   si   so    bi    bo   in   cs  us sy  id wa st
  31 15          0     287216        576   38606628    0    0     2  1158    2   14   1  3  95  0  0
  27 15          0     225288        576   38583384    0    0    18 2222016 203357 134876  11 56  17 15  0
  28 17          0     219256        576   38544736    0    0    11 2305932 203141 146296  11 49  23 17  0
   6 18          0     215596        576   38552872    0    0     7 2363207 215264 166502  12 45  22 20  0
  22 18          0     226984        576   38596404    0    0     3 2445741 223114 179527  12 43  23 22  0

and then it goes to pot

  procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu-------
   r  b       swpd       free       buff      cache   si   so    bi    bo   in   cs  us sy  id wa st
  163  8          0     464308        576   36791368    0    0    11 22210  866  536   3 13  79  4  0
  207 14          0     917752        576   36181928    0    0   712 1345376 134598 47367   7 90   1  2  0
  123 12          0     685516        576   36296148    0    0   429 1386615 158494 60077   8 84   5  3  0
  123 12          0     598572        576   36333728    0    0  1107 1233281 147542 62351   7 84   5  4  0
  622  7          0     660768        576   36118264    0    0   557 1345548 151394 59353   7 85   4  3  0
  223 11          0     283960        576   36463868    0    0    46 1107160 121846 33006   6 93   1  1  0

Note that system CPU usage is very high blocks being written out has
dropped by 42%. He analysed this with perf and found

  perf record -g -a sleep 10
  perf report --sort symbol --call-graph fractal,5
    34.63%  [k] _raw_spin_lock_irqsave
            |
            |--97.30%-- isolate_freepages
            |          compaction_alloc
            |          unmap_and_move
            |          migrate_pages
            |          compact_zone
            |          compact_zone_order
            |          try_to_compact_pages
            |          __alloc_pages_direct_compact
            |          __alloc_pages_slowpath
            |          __alloc_pages_nodemask
            |          alloc_pages_vma
            |          do_huge_pmd_anonymous_page
            |          handle_mm_fault
            |          do_page_fault
            |          page_fault
            |          |
            |          |--87.39%-- skb_copy_datagram_iovec
            |          |          tcp_recvmsg
            |          |          inet_recvmsg
            |          |          sock_recvmsg
            |          |          sys_recvfrom
            |          |          system_call
            |          |          __recv
            |          |          |
            |          |           --100.00%-- (nil)
            |          |
            |           --12.61%-- memcpy
             --2.70%-- [...]

There was other data but primarily it is all showing that compaction is
contended heavily on the zone->lock and zone->lru_lock.

commit [b2eef8c0: mm: compaction: minimise the time IRQs are disabled
while isolating pages for migration] noted that it was possible for
migration to hold the lru_lock for an excessive amount of time. Very
broadly speaking this patch expands the concept.

This patch introduces compact_checklock_irqsave() to check if a lock
is contended or the process needs to be scheduled. If either condition
is true then async compaction is aborted and the caller is informed.
The page allocator will fail a THP allocation if compaction failed due
to contention. This patch also introduces compact_trylock_irqsave()
which will acquire the lock only if it is not contended and the process
does not need to schedule.

Reported-by: Jim Schutt <jaschut@sandia.gov>
Tested-by: Jim Schutt <jaschut@sandia.gov>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-21 16:45:03 -07:00
Alex Shi b121186ab1 mm: correct page->pfmemalloc to fix deactivate_slab regression
Commit cfd19c5a9e ("mm: only set page->pfmemalloc when
ALLOC_NO_WATERMARKS was used") tried to narrow down page->pfmemalloc
setting, but it missed some places the pfmemalloc should be set.

So, in __slab_alloc, the unalignment pfmemalloc and ALLOC_NO_WATERMARKS
cause incorrect deactivate_slab() on our core2 server:

    64.73%           fio  [kernel.kallsyms]     [k] _raw_spin_lock
                     |
                     --- _raw_spin_lock
                        |
                        |---0.34%-- deactivate_slab
                        |          __slab_alloc
                        |          kmem_cache_alloc
                        |          |

That causes our fio sync write performance to have a 40% regression.

Move the checking in get_page_from_freelist() which resolves this issue.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Sage Weil <sage@inktank.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-21 16:45:03 -07:00
Linus Torvalds 8783b6e2b2 mm: remove node_start_pfn checking in new WARN_ON for now
Borislav Petkov reports that the new warning added in commit
88fdf75d1b ("mm: warn if pg_data_t isn't initialized with zero")
triggers for him, and it is the node_start_pfn field that has already
been initialized once.

The call trace looks like this:

  x86_64_start_kernel ->
    x86_64_start_reservations ->
    start_kernel ->
    setup_arch ->
    paging_init ->
    zone_sizes_init ->
    free_area_init_nodes ->
    free_area_init_node

and (with the warning replaced by debug output), Borislav sees

  On node 0 totalpages: 4193848
    DMA zone: 64 pages used for memmap
    DMA zone: 6 pages reserved
    DMA zone: 3890 pages, LIFO batch:0
    DMA32 zone: 16320 pages used for memmap
    DMA32 zone: 798464 pages, LIFO batch:31
    Normal zone: 52736 pages used for memmap
    Normal zone: 3322368 pages, LIFO batch:31
  free_area_init_node: pgdat->node_start_pfn: 4423680      <----
  On node 1 totalpages: 4194304
    Normal zone: 65536 pages used for memmap
    Normal zone: 4128768 pages, LIFO batch:31
  free_area_init_node: pgdat->node_start_pfn: 8617984      <----
  On node 2 totalpages: 4194304
    Normal zone: 65536 pages used for memmap
    Normal zone: 4128768 pages, LIFO batch:31
  free_area_init_node: pgdat->node_start_pfn: 12812288     <----
  On node 3 totalpages: 4194304
    Normal zone: 65536 pages used for memmap
    Normal zone: 4128768 pages, LIFO batch:31

so remove the bogus warning for now to avoid annoying people.  Minchan
Kim is looking at it.

Reported-by: Borislav Petkov <bp@amd64.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-02 10:37:03 -07:00
Minchan Kim 6527af5d1b mm: remove redundant initialization
pg_data_t is zeroed before reaching free_area_init_core(), so remove the
now unnecessary initializations.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:50 -07:00
Minchan Kim 88fdf75d1b mm: warn if pg_data_t isn't initialized with zero
Warn if memory-hotplug/boot code doesn't initialize pg_data_t with zero
when it is allocated.  Arch code and memory hotplug already initiailize
pg_data_t.  So this warning should never happen.  I select fields randomly
near the beginning, middle and end of pg_data_t for checking.

This patch isn't for performance but for removing initialization code
which is necessary to add whenever we adds new field to pg_data_t or zone.

Firstly, Andrew suggested clearing out of pg_data_t in MM core part but
Tejun doesn't like it because in the future, some archs can initialize
some fields in arch code and pass them into general MM part so blindly
clearing it out in mm core part would be very annoying.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:50 -07:00
Mel Gorman 5515061d22 mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
If swap is backed by network storage such as NBD, there is a risk that a
large number of reclaimers can hang the system by consuming all
PF_MEMALLOC reserves.  To avoid these hangs, the administrator must tune
min_free_kbytes in advance which is a bit fragile.

This patch throttles direct reclaimers if half the PF_MEMALLOC reserves
are in use.  If the system is routinely getting throttled the system
administrator can increase min_free_kbytes so degradation is smoother but
the system will keep running.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:46 -07:00
Mel Gorman 183f6371aa mm: ignore mempolicies when using ALLOC_NO_WATERMARK
The reserve is proportionally distributed over all !highmem zones in the
system.  So we need to allow an emergency allocation access to all zones.
In order to do that we need to break out of any mempolicy boundaries we
might have.

In my opinion that does not break mempolicies as those are user oriented
and not system oriented.  That is, system allocations are not guaranteed
to be within mempolicy boundaries.  For instance IRQs do not even have a
mempolicy.

So breaking out of mempolicy boundaries for 'rare' emergency allocations,
which are always system allocations (as opposed to user) is ok.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Mel Gorman cfd19c5a9e mm: only set page->pfmemalloc when ALLOC_NO_WATERMARKS was used
__alloc_pages_slowpath() is called when the number of free pages is below
the low watermark.  If the caller is entitled to use ALLOC_NO_WATERMARKS
then the page will be marked page->pfmemalloc.  This protects more pages
than are strictly necessary as we only need to protect pages allocated
below the min watermark (the pfmemalloc reserves).

This patch only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was
required to allocate the page.

[rientjes@google.com: David noticed the problem during review]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Mel Gorman 907aed48f6 mm: allow PF_MEMALLOC from softirq context
This is needed to allow network softirq packet processing to make use of
PF_MEMALLOC.

Currently softirq context cannot use PF_MEMALLOC due to it not being
associated with a task, and therefore not having task flags to fiddle with
- thus the gfp to alloc flag mapping ignores the task flags when in
interrupts (hard or soft) context.

Allowing softirqs to make use of PF_MEMALLOC therefore requires some
trickery.  This patch borrows the task flags from whatever process happens
to be preempted by the softirq.  It then modifies the gfp to alloc flags
mapping to not exclude task flags in softirq context, and modify the
softirq code to save, clear and restore the PF_MEMALLOC flag.

The save and clear, ensures the preempted task's PF_MEMALLOC flag doesn't
leak into the softirq.  The restore ensures a softirq's PF_MEMALLOC flag
cannot leak back into the preempted process.  This should be safe due to
the following reasons

Softirqs can run on multiple CPUs sure but the same task should not be
	executing the same softirq code. Neither should the softirq
	handler be preempted by any other softirq handler so the flags
	should not leak to an unrelated softirq.

Softirqs re-enable hardware interrupts in __do_softirq() so can be
	preempted by hardware interrupts so PF_MEMALLOC is inherited
	by the hard IRQ. However, this is similar to a process in
	reclaim being preempted by a hardirq. While PF_MEMALLOC is
	set, gfp_to_alloc_flags() distinguishes between hard and
	soft irqs and avoids giving a hardirq the ALLOC_NO_WATERMARKS
	flag.

If the softirq is deferred to ksoftirq then its flags may be used
        instead of a normal tasks but as the softirq cannot be preempted,
        the PF_MEMALLOC flag does not leak to other code by accident.

[davem@davemloft.net: Document why PF_MEMALLOC is safe]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Mel Gorman b37f1dd0f5 mm: introduce __GFP_MEMALLOC to allow access to emergency reserves
__GFP_MEMALLOC will allow the allocation to disregard the watermarks, much
like PF_MEMALLOC.  It allows one to pass along the memalloc state in
object related allocation flags as opposed to task related flags, such as
sk->sk_allocation.  This removes the need for ALLOC_PFMEMALLOC as callers
using __GFP_MEMALLOC can get the ALLOC_NO_WATERMARK flag which is now
enough to identify allocations related to page reclaim.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Mel Gorman 072bb0aa5e mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon.  Swap over the network is considered as an option in diskless
systems.  The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.

The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap.  Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively.  This patch series addresses the problem.

The core issue is that network block devices do not use mempools like
normal block devices do.  As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need.  Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels.  This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS.  The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.

Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
	preserve access to pages allocated under low memory situations
	to callers that are freeing memory.

Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks

Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
	reserves without setting PFMEMALLOC.

Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
	for later use by network packet processing.

Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required

Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.

Patches 7-12 allows network processing to use PFMEMALLOC reserves when
	the socket has been marked as being used by the VM to clean pages. If
	packets are received and stored in pages that were allocated under
	low-memory situations and are unrelated to the VM, the packets
	are dropped.

	Patch 11 reintroduces __skb_alloc_page which the networking
	folk may object to but is needed in some cases to propogate
	pfmemalloc from a newly allocated page to an skb. If there is a
	strong objection, this patch can be dropped with the impact being
	that swap-over-network will be slower in some cases but it should
	not fail.

Patch 13 is a micro-optimisation to avoid a function call in the
	common case.

Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
	PFMEMALLOC if necessary.

Patch 15 notes that it is still possible for the PFMEMALLOC reserve
	to be depleted. To prevent this, direct reclaimers get throttled on
	a waitqueue if 50% of the PFMEMALLOC reserves are depleted.  It is
	expected that kswapd and the direct reclaimers already running
	will clean enough pages for the low watermark to be reached and
	the throttled processes are woken up.

Patch 16 adds a statistic to track how often processes get throttled

Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench.  Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.

For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD.  8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop.  The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.

Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied.  With SLAB, the story is
different as an unpatched kernel run to completion.  However, the patched
kernel completed the test 45% faster.

MICRO
                                         3.5.0-rc2 3.5.0-rc2
					 vanilla     swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds)             197.80    173.07
User+Sys Time Running Test (seconds)        206.96    182.03
Total Elapsed Time (seconds)               3240.70   1762.09

This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages

Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory.  To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS.  Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs.  This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.

When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected.  SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve.  If one is not available, an attempt is
made to allocate a new page rather than use a reserve.  SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags.  This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.

In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.

[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Minchan Kim 702d1a6e07 memory-hotplug: fix kswapd looping forever problem
When hotplug offlining happens on zone A, it starts to mark freed page as
MIGRATE_ISOLATE type in buddy for preventing further allocation.
(MIGRATE_ISOLATE is very irony type because it's apparently on buddy but
we can't allocate them).

When the memory shortage happens during hotplug offlining, current task
starts to reclaim, then wake up kswapd.  Kswapd checks watermark, then go
sleep because current zone_watermark_ok_safe doesn't consider
MIGRATE_ISOLATE freed page count.  Current task continue to reclaim in
direct reclaim path without kswapd's helping.  The problem is that
zone->all_unreclaimable is set by only kswapd so that current task would
be looping forever like below.

__alloc_pages_slowpath
restart:
	wake_all_kswapd
rebalance:
	__alloc_pages_direct_reclaim
		do_try_to_free_pages
			if global_reclaim && !all_unreclaimable
				return 1; /* It means we did did_some_progress */
	skip __alloc_pages_may_oom
	should_alloc_retry
		goto rebalance;

If we apply KOSAKI's patch[1] which doesn't depends on kswapd about
setting zone->all_unreclaimable, we can solve this problem by killing some
task in direct reclaim path.  But it doesn't wake up kswapd, still.  It
could be a problem still if other subsystem needs GFP_ATOMIC request.  So
kswapd should consider MIGRATE_ISOLATE when it calculate free pages BEFORE
going sleep.

This patch counts the number of MIGRATE_ISOLATE page block and
zone_watermark_ok_safe will consider it if the system has such blocks
(fortunately, it's very rare so no problem in POV overhead and kswapd is
never hotpath).

Copy/modify from Mel's quote
"
Ideal solution would be "allocating" the pageblock.
It would keep the free space accounting as it is but historically,
memory hotplug didn't allocate pages because it would be difficult to
detect if a pageblock was isolated or if part of some balloon.
Allocating just full pageblocks would work around this, However,
it would play very badly with CMA.
"

[1] http://lkml.org/lkml/2012/6/14/74

[akpm@linux-foundation.org: simplify nr_zone_isolate_freepages(), rework zone_watermark_ok_safe() comment, simplify set_pageblock_isolate() and restore_pageblock_isolate()]
[akpm@linux-foundation.org: fix CONFIG_MEMORY_ISOLATION=n build]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Suggested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: Aaditya Kumar <aaditya.kumar.30@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Minchan Kim 2cfed07528 mm: fix free page check in zone_watermark_ok()
__zone_watermark_ok currently compares free_pages which is a signed type
with z->lowmem_reserve[classzone_idx] which is unsigned which might lead
to sign overflow if free_pages doesn't satisfy the given order (or it came
as negative already) and then we rely on the following order loop to fix
it (which doesn't work for order-0).  Let's fix the type conversion and do
not rely on the given value of free_pages or follow up fixups.

This patch fixes it because "memory-hotplug: fix kswapd looping forever
problem" depends on this.

As benefit of this patch, it doesn't rely on the loop to exit
__zone_watermark_ok in case of high order check and make the first test
effective.(ie, if (free_pages <= min + lowmem_reserve))

Aaditya reported this problem when he test my hotplug patch.

Reported-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Tested-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Minchan Kim ee6f509c32 mm: factor out memory isolate functions
mm/page_alloc.c has some memory isolation functions but they are used only
when we enable CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}.  So let's make
it configurable by new CONFIG_MEMORY_ISOLATION so that it can reduce
binary size and we can check it simple by CONFIG_MEMORY_ISOLATION, not if
defined CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:45 -07:00
Jiang Liu 4ed7e02222 mm/hotplug: mark memory hotplug code in page_alloc.c as __meminit
Mark functions used by both boot and memory hotplug as __meminit to reduce
memory footprint when memory hotplug is disabled.

Alos guard zone_pcp_update() with CONFIG_MEMORY_HOTPLUG because it's only
used by memory hotplug code.

Signed-off-by: Jiang Liu <liuj97@gmail.com>
Cc: Wei Wang <Bessel.Wang@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Keping Chen <chenkeping@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:44 -07:00
Jiang Liu 340175b7d1 mm/hotplug: free zone->pageset when a zone becomes empty
When a zone becomes empty after memory offlining, free zone->pageset.
Otherwise it will cause memory leak when adding memory to the empty zone
again because build_all_zonelists() will allocate zone->pageset for an
empty zone.

Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Wei Wang <Bessel.Wang@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Keping Chen <chenkeping@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:44 -07:00
Jiang Liu 9adb62a5df mm/hotplug: correctly setup fallback zonelists when creating new pgdat
When hotadd_new_pgdat() is called to create new pgdat for a new node, a
fallback zonelist should be created for the new node.  There's code to try
to achieve that in hotadd_new_pgdat() as below:

	/*
	 * The node we allocated has no zone fallback lists. For avoiding
	 * to access not-initialized zonelist, build here.
	 */
	mutex_lock(&zonelists_mutex);
	build_all_zonelists(pgdat, NULL);
	mutex_unlock(&zonelists_mutex);

But it doesn't work as expected.  When hotadd_new_pgdat() is called, the
new node is still in offline state because node_set_online(nid) hasn't
been called yet.  And build_all_zonelists() only builds zonelists for
online nodes as:

        for_each_online_node(nid) {
                pg_data_t *pgdat = NODE_DATA(nid);

                build_zonelists(pgdat);
                build_zonelist_cache(pgdat);
        }

Though we hope to create zonelist for the new pgdat, but it doesn't.  So
add a new parameter "pgdat" the build_all_zonelists() to build pgdat for
the new pgdat too.

Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Keping Chen <chenkeping@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:44 -07:00
Xishi Qiu ca57df79d4 mm: setup pageblock_order before it's used by sparsemem
On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as
Itanium, pageblock_order is a variable with default value of 0.  It's set
to the right value by set_pageblock_order() in function
free_area_init_core().

But pageblock_order may be used by sparse_init() before free_area_init_core()
is called along path:
sparse_init()
    ->sparse_early_usemaps_alloc_node()
	->usemap_size()
	    ->SECTION_BLOCKFLAGS_BITS
		->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) *
NR_PAGEBLOCK_BITS)

The uninitialized pageblock_size will cause memory wasting because
usemap_size() returns a much bigger value then it's really needed.

For example, on an Itanium platform,
sparse_init() pageblock_order=0 usemap_size=24576
free_area_init_core() before pageblock_order=0, usemap_size=24576
free_area_init_core() after pageblock_order=12, usemap_size=8

That means 24K memory has been wasted for each section, so fix it by calling
set_pageblock_order() from sparse_init().

Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Keping Chen <chenkeping@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:43 -07:00
Rik van Riel 7db8889ab0 mm: have order > 0 compaction start off where it left
Order > 0 compaction stops when enough free pages of the correct page
order have been coalesced.  When doing subsequent higher order
allocations, it is possible for compaction to be invoked many times.

However, the compaction code always starts out looking for things to
compact at the start of the zone, and for free pages to compact things to
at the end of the zone.

This can cause quadratic behaviour, with isolate_freepages starting at the
end of the zone each time, even though previous invocations of the
compaction code already filled up all free memory on that end of the zone.

This can cause isolate_freepages to take enormous amounts of CPU with
certain workloads on larger memory systems.

The obvious solution is to have isolate_freepages remember where it left
off last time, and continue at that point the next time it gets invoked
for an order > 0 compaction.  This could cause compaction to fail if
cc->free_pfn and cc->migrate_pfn are close together initially, in that
case we restart from the end of the zone and try once more.

Forced full (order == -1) compactions are left alone.

[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: s/laste/last/, use 80 cols]
Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Jim Schutt <jaschut@sandia.gov>
Tested-by: Jim Schutt <jaschut@sandia.gov>
Cc: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:43 -07:00
Minchan Kim 80934513b2 mm: clean up __count_immobile_pages()
The __count_immobile_pages() naming is rather awkward.  Choose a more
clear name and add a comment.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:42 -07:00
Minchan Kim 97d255c816 mm: do not use page_count() without a page pin
d179e84ba ("mm: vmscan: do not use page_count without a page pin") fixed
this problem in vmscan.c but same problem is in __count_immobile_pages().

I copy and paste d179e84ba's contents for description.

"It is unsafe to run page_count during the physical pfn scan because
compound_head could trip on a dangling pointer when reading
page->first_page if the compound page is being freed by another CPU."

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wanpeng Li <liwp.linux@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:42 -07:00
KOSAKI Motohiro 2a13515c39 mm: clear pages_scanned only if draining a pcp adds pages to the buddy allocator again
commit 2ff754fa8f ("mm: clear pages_scanned only if draining a pcp adds
pages to the buddy allocator again") fixed one free_pcppages_bulk()
misuse.  But two another miuse still exist.

This patch fixes it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:42 -07:00
Gavin Shan deaf386ee5 mm/buddy: cleanup on should_fail_alloc_page
Currently, function should_fail() has "bool" for its return value, so it's
reasonable to change the return value of function should_fail_alloc_page()
into "bool" as well.

The patch does cleanup on function should_fail_alloc_page() to have "bool"
for its return value.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:40 -07:00
Rabin Vincent 6a6dccba2f mm: cma: don't replace lowmem pages with highmem
The filesystem layer expects pages in the block device's mapping to not
be in highmem (the mapping's gfp mask is set in bdget()), but CMA can
currently replace lowmem pages with highmem pages, leading to crashes in
filesystem code such as the one below:

  Unable to handle kernel NULL pointer dereference at virtual address 00000400
  pgd = c0c98000
  [00000400] *pgd=00c91831, *pte=00000000, *ppte=00000000
  Internal error: Oops: 817 [#1] PREEMPT SMP ARM
  CPU: 0    Not tainted  (3.5.0-rc5+ #80)
  PC is at __memzero+0x24/0x80
  ...
  Process fsstress (pid: 323, stack limit = 0xc0cbc2f0)
  Backtrace:
  [<c010e3f0>] (ext4_getblk+0x0/0x180) from [<c010e58c>] (ext4_bread+0x1c/0x98)
  [<c010e570>] (ext4_bread+0x0/0x98) from [<c0117944>] (ext4_mkdir+0x160/0x3bc)
   r4:c15337f0
  [<c01177e4>] (ext4_mkdir+0x0/0x3bc) from [<c00c29e0>] (vfs_mkdir+0x8c/0x98)
  [<c00c2954>] (vfs_mkdir+0x0/0x98) from [<c00c2a60>] (sys_mkdirat+0x74/0xac)
   r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0
  [<c00c29ec>] (sys_mkdirat+0x0/0xac) from [<c00c2ab8>] (sys_mkdir+0x20/0x24)
   r6:beccdcf0 r5:00074000 r4:beccdbbc
  [<c00c2a98>] (sys_mkdir+0x0/0x24) from [<c000e3c0>] (ret_fast_syscall+0x0/0x30)

Fix this by replacing only highmem pages with highmem.

Reported-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Rabin Vincent <rabin@rab.in>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
2012-07-06 11:07:04 +02:00
Linus Torvalds 68e3e92620 Revert "mm: compaction: handle incorrect MIGRATE_UNMOVABLE type pageblocks"
This reverts commit 5ceb9ce6fe.

That commit seems to be the cause of the mm compation list corruption
issues that Dave Jones reported.  The locking (or rather, absense
there-of) is dubious, as is the use of the 'page' variable once it has
been found to be outside the pageblock range.

So revert it for now, we can re-visit this for 3.6.  If we even need to:
as Minchan Kim says, "The patch wasn't a bug fix and even test workload
was very theoretical".

Reported-and-tested-by: Dave Jones <davej@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-03 20:05:57 -07:00
Konstantin Khlebnikov 7f5e86c2cc mm: add link from struct lruvec to struct zone
This is the first stage of struct mem_cgroup_zone removal.  Further
patches replace struct mem_cgroup_zone with a pointer to struct lruvec.

If CONFIG_CGROUP_MEM_RES_CTLR=n lruvec_zone() is just container_of().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00