linux-toradex.git/include/linux/migrate.h, branch v4.6-rc6

mm, page_owner: track and print last migrate reason

2016-03-15T23:55:16+00:00

During migration, page_owner info is now copied with the rest of the
page, so the stacktrace leading to free page allocation during migration
is overwritten.  For debugging purposes, it might be however useful to
know that the page has been migrated since its initial allocation.  This
might happen many times during the lifetime for different reasons and
fully tracking this, especially with stacktraces would incur extra
memory costs.  As a compromise, store and print the migrate_reason of
the last migration that occurred to the page.  This is enough to
distinguish compaction, numa balancing etc.

Example page_owner entry after the patch:

  Page allocated via order 0, mask 0x24200ca(GFP_HIGHUSER_MOVABLE)
  PFN 628753 type Movable Block 1228 type Movable Flags 0x1fffff80040030(dirty|lru|swapbacked)
   [] __alloc_pages_nodemask+0x134/0x230
   [] alloc_pages_vma+0xb5/0x250
   [] shmem_alloc_page+0x61/0x90
   [] shmem_getpage_gfp+0x678/0x960
   [] shmem_fallocate+0x329/0x440
   [] vfs_fallocate+0x140/0x230
   [] SyS_fallocate+0x44/0x70
   [] entry_SYSCALL_64_fastpath+0x12/0x71
  Page has been migrated, last migrate reason: compaction

Signed-off-by: Vlastimil Babka 
Cc: Joonsoo Kim 
Cc: Minchan Kim 
Cc: Sasha Levin 
Cc: "Kirill A. Shutemov" 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: numa: remove migrate_ratelimited

2015-04-14T23:49:05+00:00

This code is dead since commit 9e645ab6d089 ("sched/numa: Continue PTE
scanning even if migrate rate limited") so remove it.

Signed-off-by: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: numa: do not dereference pmd outside of the lock during NUMA hinting fault

2015-02-13T02:54:08+00:00

Automatic NUMA balancing depends on being able to protect PTEs to trap a
fault and gather reference locality information.  Very broadly speaking
it would mark PTEs as not present and use another bit to distinguish
between NUMA hinting faults and other types of faults.  It was
universally loved by everybody and caused no problems whatsoever.  That
last sentence might be a lie.

This series is very heavily based on patches from Linus and Aneesh to
replace the existing PTE/PMD NUMA helper functions with normal change
protections.  I did alter and add parts of it but I consider them
relatively minor contributions.  At their suggestion, acked-bys are in
there but I've no problem converting them to Signed-off-by if requested.

AFAIK, this has received no testing on ppc64 and I'm depending on Aneesh
for that.  I tested trinity under kvm-tool and passed and ran a few
other basic tests.  At the time of writing, only the short-lived tests
have completed but testing of V2 indicated that long-term testing had no
surprises.  In most cases I'm leaving out detail as it's not that
interesting.

specjbb single JVM: There was negligible performance difference in the
	benchmark itself for short runs. However, system activity is
	higher and interrupts are much higher over time -- possibly TLB
	flushes. Migrations are also higher. Overall, this is more overhead
	but considering the problems faced with the old approach I think
	we just have to suck it up and find another way of reducing the
	overhead.

specjbb multi JVM: Negligible performance difference to the actual benchmark
	but like the single JVM case, the system overhead is noticeably
	higher.  Again, interrupts are a major factor.

autonumabench: This was all over the place and about all that can be
	reasonably concluded is that it's different but not necessarily
	better or worse.

autonumabench
                                     3.18.0-rc5            3.18.0-rc5
                                 mmotm-20141119         protnone-v3r3
User    NUMA01               32380.24 (  0.00%)    21642.92 ( 33.16%)
User    NUMA01_THEADLOCAL    22481.02 (  0.00%)    22283.22 (  0.88%)
User    NUMA02                3137.00 (  0.00%)     3116.54 (  0.65%)
User    NUMA02_SMT            1614.03 (  0.00%)     1543.53 (  4.37%)
System  NUMA01                 322.97 (  0.00%)     1465.89 (-353.88%)
System  NUMA01_THEADLOCAL       91.87 (  0.00%)       49.32 ( 46.32%)
System  NUMA02                  37.83 (  0.00%)       14.61 ( 61.38%)
System  NUMA02_SMT               7.36 (  0.00%)        7.45 ( -1.22%)
Elapsed NUMA01                 716.63 (  0.00%)      599.29 ( 16.37%)
Elapsed NUMA01_THEADLOCAL      553.98 (  0.00%)      539.94 (  2.53%)
Elapsed NUMA02                  83.85 (  0.00%)       83.04 (  0.97%)
Elapsed NUMA02_SMT              86.57 (  0.00%)       79.15 (  8.57%)
CPU     NUMA01                4563.00 (  0.00%)     3855.00 ( 15.52%)
CPU     NUMA01_THEADLOCAL     4074.00 (  0.00%)     4136.00 ( -1.52%)
CPU     NUMA02                3785.00 (  0.00%)     3770.00 (  0.40%)
CPU     NUMA02_SMT            1872.00 (  0.00%)     1959.00 ( -4.65%)

System CPU usage of NUMA01 is worse but it's an adverse workload on this
machine so I'm reluctant to conclude that it's a problem that matters.  On
the other workloads that are sensible on this machine, system CPU usage is
great.  Overall time to complete the benchmark is comparable

          3.18.0-rc5  3.18.0-rc5
        mmotm-20141119protnone-v3r3
User        59612.50    48586.44
System        460.22     1537.45
Elapsed      1442.20     1304.29

NUMA alloc hit                 5075182     5743353
NUMA alloc miss                      0           0
NUMA interleave hit                  0           0
NUMA alloc local               5075174     5743339
NUMA base PTE updates        637061448   443106883
NUMA huge PMD updates          1243434      864747
NUMA page range updates     1273699656   885857347
NUMA hint faults               1658116     1214277
NUMA hint local faults          959487      754113
NUMA hint local percent             57          62
NUMA pages migrated            5467056    61676398

The NUMA pages migrated look terrible but when I looked at a graph of the
activity over time I see that the massive spike in migration activity was
during NUMA01.  This correlates with high system CPU usage and could be
simply down to bad luck but any modifications that affect that workload
would be related to scan rates and migrations, not the protection
mechanism.  For all other workloads, migration activity was comparable.

Overall, headline performance figures are comparable but the overhead is
higher, mostly in interrupts.  To some extent, higher overhead from this
approach was anticipated but not to this degree.  It's going to be
necessary to reduce this again with a separate series in the future.  It's
still worth going ahead with this series though as it's likely to avoid
constant headaches with Xen and is probably easier to maintain.

This patch (of 10):

A transhuge NUMA hinting fault may find the page is migrating and should
wait until migration completes.  The check is race-prone because the pmd
is deferenced outside of the page lock and while the race is tiny, it'll
be larger if the PMD is cleared while marking PMDs for hinting fault.
This patch closes the race.

Signed-off-by: Mel Gorman 
Cc: Aneesh Kumar K.V 
Cc: Benjamin Herrenschmidt 
Cc: Dave Jones 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Kirill Shutemov 
Cc: Linus Torvalds 
Cc: Paul Mackerras 
Cc: Rik van Riel 
Cc: Sasha Levin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vm_area_operations: kill ->migrate()

2014-12-17T13:26:51+00:00

the only instance this method has ever grown was one in kernfs -
one that call ->migrate() of another vm_ops if it exists.

Signed-off-by: Al Viro

mm/balloon_compaction: redesign ballooned pages management

2014-10-10T02:26:01+00:00

Sasha Levin reported KASAN splash inside isolate_migratepages_range().
Problem is in the function __is_movable_balloon_page() which tests
AS_BALLOON_MAP in page->mapping->flags.  This function has no protection
against anonymous pages.  As result it tried to check address space flags
inside struct anon_vma.

Further investigation shows more problems in current implementation:

* Special branch in __unmap_and_move() never works:
  balloon_page_movable() checks page flags and page_count.  In
  __unmap_and_move() page is locked, reference counter is elevated, thus
  balloon_page_movable() always fails.  As a result execution goes to the
  normal migration path.  virtballoon_migratepage() returns
  MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS,
  move_to_new_page() thinks this is an error code and assigns
  newpage->mapping to NULL.  Newly migrated page lose connectivity with
  balloon an all ability for further migration.

* lru_lock erroneously required in isolate_migratepages_range() for
  isolation ballooned page.  This function releases lru_lock periodically,
  this makes migration mostly impossible for some pages.

* balloon_page_dequeue have a tight race with balloon_page_isolate:
  balloon_page_isolate could be executed in parallel with dequeue between
  picking page from list and locking page_lock.  Race is rare because they
  use trylock_page() for locking.

This patch fixes all of them.

Instead of fake mapping with special flag this patch uses special state of
page->_mapcount: PAGE_BALLOON_MAPCOUNT_VALUE = -256.  Buddy allocator uses
PAGE_BUDDY_MAPCOUNT_VALUE = -128 for similar purpose.  Storing mark
directly in struct page makes everything safer and easier.

PagePrivate is used to mark pages present in page list (i.e.  not
isolated, like PageLRU for normal pages).  It replaces special rules for
reference counter and makes balloon migration similar to migration of
normal pages.  This flag is protected by page_lock together with link to
the balloon device.

Signed-off-by: Konstantin Khlebnikov 
Reported-by: Sasha Levin 
Link: http://lkml.kernel.org/p/53E6CEAA.9020105@oracle.com
Cc: Rafael Aquini 
Cc: Andrey Ryabinin 
Cc: 	[3.8+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

include/linux/migrate.h: remove migrate_page #define

2014-10-10T02:25:56+00:00

This is designed to avoid a few ifdefs in .c files but it's obnoxious
because it can cause unsuspecting "migrate_page" symbols to get turned into
"NULL".

Just nuke it and use the ifdefs.

Cc: Konstantin Khlebnikov 
Cc: Rafael Aquini 
Cc: Andrey Ryabinin 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, migration: add destination page freeing callback

2014-06-04T23:54:06+00:00

Memory migration uses a callback defined by the caller to determine how to
allocate destination pages.  When migration fails for a source page,
however, it frees the destination page back to the system.

This patch adds a memory migration callback defined by the caller to
determine how to free destination pages.  If a caller, such as memory
compaction, builds its own freelist for migration targets, this can reuse
already freed memory instead of scanning additional memory.

If the caller provides a function to handle freeing of destination pages,
it is called when page migration fails.  If the caller passes NULL then
freeing back to the system will be handled as usual.  This patch
introduces no functional change.

Signed-off-by: David Rientjes 
Reviewed-by: Naoya Horiguchi 
Acked-by: Mel Gorman 
Acked-by: Vlastimil Babka 
Cc: Greg Thelen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/migrate: remove unused function, fail_migrate_page()

2014-01-22T00:19:49+00:00

fail_migrate_page() isn't used anywhere, so remove it.

Signed-off-by: Joonsoo Kim 
Acked-by: Christoph Lameter 
Reviewed-by: Naoya Horiguchi 
Reviewed-by: Wanpeng Li 
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

mm/migrate: remove putback_lru_pages, fix comment on putback_movable_pages

2014-01-22T00:19:49+00:00

Some part of putback_lru_pages() and putback_movable_pages() is
duplicated, so it could confuse us what we should use.  We can remove
putback_lru_pages() since it is not really needed now.  This makes us
undestand and maintain the code more easily.

And comment on putback_movable_pages() is stale now, so fix it.

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

aio/migratepages: make aio migrate pages sane

2013-12-21T22:56:08+00:00

The arbitrary restriction on page counts offered by the core
migrate_page_move_mapping() code results in rather suspicious looking
fiddling with page reference counts in the aio_migratepage() operation.
To fix this, make migrate_page_move_mapping() take an extra_count parameter
that allows aio to tell the code about its own reference count on the page
being migrated.

While cleaning up aio_migratepage(), make it validate that the old page
being passed in is actually what aio_migratepage() expects to prevent
misbehaviour in the case of races.

Signed-off-by: Benjamin LaHaise