linux-toradex.git/mm/compaction.c, branch v3.12.14

mm/compaction: respect ignore_skip_hint in update_pageblock_skip

2014-01-09T20:25:14+00:00

commit 6815bf3f233e0b10c99a758497d5d236063b010b upstream.

update_pageblock_skip() only fits to compaction which tries to isolate
by pageblock unit.  If isolate_migratepages_range() is called by CMA, it
try to isolate regardless of pageblock unit and it don't reference
get_pageblock_skip() by ignore_skip_hint.  We should also respect it on
update_pageblock_skip() to prevent from setting the wrong information.

Signed-off-by: Joonsoo Kim 
Acked-by: Vlastimil Babka 
Reviewed-by: Naoya Horiguchi 
Reviewed-by: Wanpeng Li 
Cc: Christoph Lameter 
Cc: Rafael Aquini 
Cc: Vlastimil Babka 
Cc: Wanpeng Li 
Cc: Mel Gorman 
Cc: Rik van Riel 
Cc: Zhang Yanfei 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm/compaction.c: periodically schedule when freeing pages

2013-09-30T21:31:01+00:00

We've been getting warnings about an excessive amount of time spent
allocating pages for migration during memory compaction without
scheduling.  isolate_freepages_block() already periodically checks for
contended locks or the need to schedule, but isolate_freepages() never
does.

When a zone is massively long and no suitable targets can be found, this
iteration can be quite expensive without ever doing cond_resched().

Check periodically for the need to reschedule while the compaction free
scanner iterates.

Signed-off-by: David Rientjes 
Reviewed-by: Rik van Riel 
Reviewed-by: Wanpeng Li 
Acked-by: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: compaction: do not compact pgdat for order-0

2013-09-11T22:57:55+00:00

If kswapd was reclaiming for a high order and resets it to 0 due to
fragmentation it will still call compact_pgdat.  For the most part, this
will fail a compaction_suitable() test and not compact but it is
unnecessarily sloppy.  It could be fixed in the caller but fix it in the
API instead.

[dhillf@gmail.com: pointed out that it was a potential problem]
Signed-off-by: Mel Gorman 
Cc: Hillf Danton 
Acked-by: Minchan Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: add & use zone_end_pfn() and zone_spans_pfn()

2013-02-24T01:50:20+00:00

Add 2 helpers (zone_end_pfn() and zone_spans_pfn()) to reduce code
duplication.

This also switches to using them in compaction (where an additional
variable needed to be renamed), page_alloc, vmstat, memory_hotplug, and
kmemleak.

Note that in compaction.c I avoid calling zone_end_pfn() repeatedly
because I expect at some point the sycronization issues with start_pfn &
spanned_pages will need fixing, either by actually using the seqlock or
clever memory barrier usage.

Signed-off-by: Cody P Schafer 
Cc: David Hansen 
Cc: Catalin Marinas 
Cc: Johannes Weiner 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove offlining arg to migrate_pages

2013-02-24T01:50:19+00:00

No functional change, but the only purpose of the offlining argument to
migrate_pages() etc, was to ensure that __unmap_and_move() could migrate a
KSM page for memory hotremove (which took ksm_thread_mutex) but not for
other callers.  Now all cases are safe, remove the arg.

Signed-off-by: Hugh Dickins 
Cc: Rik van Riel 
Cc: Petr Holasek 
Cc: Andrea Arcangeli 
Cc: Izik Eidus 
Cc: Gerald Schaefer 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove MIGRATE_ISOLATE check in hotpath

2013-02-24T01:50:15+00:00

Several functions test MIGRATE_ISOLATE and some of those are hotpath but
MIGRATE_ISOLATE is used only if we enable CONFIG_MEMORY_ISOLATION(ie,
CMA, memory-hotplug and memory-failure) which are not common config
option.  So let's not add unnecessary overhead and code when we don't
enable CONFIG_MEMORY_ISOLATION.

Signed-off-by: Minchan Kim 
Cc: KOSAKI Motohiro 
Acked-by: Michal Nazarewicz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: compaction: make __compact_pgdat() and compact_pgdat() return void

2013-02-24T01:50:10+00:00

These functions always return 0.  Formalise this.

Cc: Jason Liu 
Cc: KAMEZAWA Hiroyuki 
Cc: Mel Gorman 
Cc: Minchan Kim 
Cc: Rik van Riel 
Acked-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: compaction: do not accidentally skip pageblocks in the migrate scanner

2013-02-24T01:50:10+00:00

Compaction uses the ALIGN macro incorrectly with the migrate scanner by
adding pageblock_nr_pages to a PFN.  It happened to work when initially
implemented as the starting PFN was also aligned but with caching
restarts and isolating in smaller chunks this is no longer always true.

The impact is that the migrate scanner scans outside its current
pageblock.  As pfn_valid() is still checked properly it does not cause
any failure and the impact of the bug is that in some cases it will scan
more than necessary when it crosses a page boundary but by no more than
COMPACT_CLUSTER_MAX.  It is highly unlikely this is even measurable but
it's still wrong so this patch addresses the problem.

Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: compaction: partially revert capture of suitable high-order page

2013-01-11T22:54:56+00:00

Eric Wong reported on 3.7 and 3.8-rc2 that ppoll() got stuck when
waiting for POLLIN on a local TCP socket.  It was easier to trigger if
there was disk IO and dirty pages at the same time and he bisected it to
commit 1fb3f8ca0e92 ("mm: compaction: capture a suitable high-order page
immediately when it is made available").

The intention of that patch was to improve high-order allocations under
memory pressure after changes made to reclaim in 3.6 drastically hurt
THP allocations but the approach was flawed.  For Eric, the problem was
that page->pfmemalloc was not being cleared for captured pages leading
to a poor interaction with swap-over-NFS support causing the packets to
be dropped.  However, I identified a few more problems with the patch
including the fact that it can increase contention on zone->lock in some
cases which could result in async direct compaction being aborted early.

In retrospect the capture patch took the wrong approach.  What it should
have done is mark the pageblock being migrated as MIGRATE_ISOLATE if it
was allocating for THP and avoided races that way.  While the patch was
showing to improve allocation success rates at the time, the benefit is
marginal given the relative complexity and it should be revisited from
scratch in the context of the other reclaim-related changes that have
taken place since the patch was first written and tested.  This patch
partially reverts commit 1fb3f8ca0e92 ("mm: compaction: capture a
suitable high-order page immediately when it is made available").

Reported-and-tested-by: Eric Wong 
Tested-by: Eric Dumazet 
Cc: 
Signed-off-by: Mel Gorman 
Cc: David Miller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: compaction: fix echo 1 > compact_memory return error issue

2013-01-11T22:54:54+00:00

when run the folloing command under shell, it will return error

  sh/$ echo 1 > /proc/sys/vm/compact_memory
  sh/$ sh: write error: Bad address

After strace, I found the following log:

  ...
  write(1, "1\n", 2)               = 3
  write(1, "", 4294967295)         = -1 EFAULT (Bad address)
  write(2, "echo: write error: Bad address\n", 31echo: write error: Bad address
  ) = 31

This tells system return 3(COMPACT_COMPLETE) after write data to
compact_memory.

The fix is to make the system just return 0 instead 3(COMPACT_COMPLETE)
from sysctl_compaction_handler after compaction_nodes finished.

Signed-off-by: Jason Liu 
Suggested-by: David Rientjes 
Acked-by: Mel Gorman 
Cc: Rik van Riel 
Cc: Minchan Kim 
Cc: KAMEZAWA Hiroyuki 
Acked-by: David Rientjes 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds