linux-stable.git/mm/compaction.c, branch linux-3.13.y

mm/compaction: break out of loop on !PageBuddy in isolate_freepages_block

2014-03-24T04:44:16+00:00

commit 2af120bc040c5ebcda156df6be6a66610ab6957f upstream.

We received several reports of bad page state when freeing CMA pages
previously allocated with alloc_contig_range:

    BUG: Bad page state in process Binder_A  pfn:63202
    page:d21130b0 count:0 mapcount:1 mapping:  (null) index:0x7dfbf
    page flags: 0x40080068(uptodate|lru|active|swapbacked)

Based on the page state, it looks like the page was still in use.  The
page flags do not make sense for the use case though.  Further debugging
showed that despite alloc_contig_range returning success, at least one
page in the range still remained in the buddy allocator.

There is an issue with isolate_freepages_block.  In strict mode (which
CMA uses), if any pages in the range cannot be isolated,
isolate_freepages_block should return failure 0.  The current check
keeps track of the total number of isolated pages and compares against
the size of the range:

        if (strict && nr_strict_required > total_isolated)
                total_isolated = 0;

After taking the zone lock, if one of the pages in the range is not in
the buddy allocator, we continue through the loop and do not increment
total_isolated.  If in the last iteration of the loop we isolate more
than one page (e.g.  last page needed is a higher order page), the check
for total_isolated may pass and we fail to detect that a page was
skipped.  The fix is to bail out if the loop immediately if we are in
strict mode.  There's no benfit to continuing anyway since we need all
pages to be isolated.  Additionally, drop the error checking based on
nr_strict_required and just check the pfn ranges.  This matches with
what isolate_freepages_range does.

Signed-off-by: Laura Abbott 
Acked-by: Minchan Kim 
Cc: Mel Gorman 
Acked-by: Vlastimil Babka 
Cc: Joonsoo Kim 
Acked-by: Bartlomiej Zolnierkiewicz 
Acked-by: Michal Nazarewicz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm/compaction: respect ignore_skip_hint in update_pageblock_skip

2013-12-19T03:04:52+00:00

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 
Cc: 	[3.7+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/compaction.c: update comment about zone lock in isolate_freepages_block

2013-11-13T03:09:03+00:00

Since commit f40d1e42bb98 ("mm: compaction: acquire the zone->lock as
late as possible"), isolate_freepages_block() takes the zone->lock
itself.  The function description however still states that the
zone->lock must be held.

This patch removes this outdated statement.

Signed-off-by: Jerome Marchand 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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