linux.git/mm/migrate.c, branch v3.12

mm: Close races between THP migration and PMD numa clearing

2013-10-29T10:38:05+00:00

THP migration uses the page lock to guard against parallel allocations
but there are cases like this still open

  Task A					Task B
  ---------------------				---------------------
  do_huge_pmd_numa_page				do_huge_pmd_numa_page
  lock_page
  mpol_misplaced == -1
  unlock_page
  goto clear_pmdnuma
						lock_page
						mpol_misplaced == 2
						migrate_misplaced_transhuge
  pmd = pmd_mknonnuma
  set_pmd_at

During hours of testing, one crashed with weird errors and while I have
no direct evidence, I suspect something like the race above happened.
This patch extends the page lock to being held until the pmd_numa is
cleared to prevent migration starting in parallel while the pmd_numa is
being cleared. It also flushes the old pmd entry and orders pagetable
insertion before rmap insertion.

Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Cc: Andrea Arcangeli 
Cc: Johannes Weiner 
Cc: Srikar Dronamraju 
Cc: 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1381141781-10992-9-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar

mm: migration: do not lose soft dirty bit if page is in migration state

2013-10-17T04:35:52+00:00

If page migration is turned on in config and the page is migrating, we
may lose the soft dirty bit.  If fork and mprotect are called on
migrating pages (once migration is complete) pages do not obtain the
soft dirty bit in the correspond pte entries.  Fix it adding an
appropriate test on swap entries.

Signed-off-by: Cyrill Gorcunov 
Cc: Pavel Emelyanov 
Cc: Andy Lutomirski 
Cc: Matt Mackall 
Cc: Xiao Guangrong 
Cc: Marcelo Tosatti 
Cc: KOSAKI Motohiro 
Cc: Stephen Rothwell 
Cc: Peter Zijlstra 
Cc: "Aneesh Kumar K.V" 
Cc: Naoya Horiguchi 
Cc: Mel Gorman 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: avoid reinserting isolated balloon pages into LRU lists

2013-09-30T21:31:02+00:00

Isolated balloon pages can wrongly end up in LRU lists when
migrate_pages() finishes its round without draining all the isolated
page list.

The same issue can happen when reclaim_clean_pages_from_list() tries to
reclaim pages from an isolated page list, before migration, in the CMA
path.  Such balloon page leak opens a race window against LRU lists
shrinkers that leads us to the following kernel panic:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
  IP: [] shrink_page_list+0x24e/0x897
  PGD 3cda2067 PUD 3d713067 PMD 0
  Oops: 0000 [#1] SMP
  CPU: 0 PID: 340 Comm: kswapd0 Not tainted 3.12.0-rc1-22626-g4367597 #87
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  RIP: shrink_page_list+0x24e/0x897
  RSP: 0000:ffff88003da499b8  EFLAGS: 00010286
  RAX: 0000000000000000 RBX: ffff88003e82bd60 RCX: 00000000000657d5
  RDX: 0000000000000000 RSI: 000000000000031f RDI: ffff88003e82bd40
  RBP: ffff88003da49ab0 R08: 0000000000000001 R09: 0000000081121a45
  R10: ffffffff81121a45 R11: ffff88003c4a9a28 R12: ffff88003e82bd40
  R13: ffff88003da0e800 R14: 0000000000000001 R15: ffff88003da49d58
  FS:  0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00000000067d9000 CR3: 000000003ace5000 CR4: 00000000000407b0
  Call Trace:
    shrink_inactive_list+0x240/0x3de
    shrink_lruvec+0x3e0/0x566
    __shrink_zone+0x94/0x178
    shrink_zone+0x3a/0x82
    balance_pgdat+0x32a/0x4c2
    kswapd+0x2f0/0x372
    kthread+0xa2/0xaa
    ret_from_fork+0x7c/0xb0
  Code: 80 7d 8f 01 48 83 95 68 ff ff ff 00 4c 89 e7 e8 5a 7b 00 00 48 85 c0 49 89 c5 75 08 80 7d 8f 00 74 3e eb 31 48 8b 80 18 01 00 00 <48> 8b 74 0d 48 8b 78 30 be 02 00 00 00 ff d2 eb
  RIP  [] shrink_page_list+0x24e/0x897
   RSP 
  CR2: 0000000000000028
  ---[ end trace 703d2451af6ffbfd ]---
  Kernel panic - not syncing: Fatal exception

This patch fixes the issue, by assuring the proper tests are made at
putback_movable_pages() & reclaim_clean_pages_from_list() to avoid
isolated balloon pages being wrongly reinserted in LRU lists.

[akpm@linux-foundation.org: clarify awkward comment text]
Signed-off-by: Rafael Aquini 
Reported-by: Luiz Capitulino 
Tested-by: Luiz Capitulino 
Cc: Mel Gorman 
Cc: Rik van Riel 
Cc: Hugh Dickins 
Cc: Johannes Weiner 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge git://git.kvack.org/~bcrl/aio-next

2013-09-13T17:55:58+00:00

Pull aio changes from Ben LaHaise:
 "First off, sorry for this pull request being late in the merge window.
  Al had raised a couple of concerns about 2 items in the series below.
  I addressed the first issue (the race introduced by Gu's use of
  mm_populate()), but he has not provided any further details on how he
  wants to rework the anon_inode.c changes (which were sent out months
  ago but have yet to be commented on).

  The bulk of the changes have been sitting in the -next tree for a few
  months, with all the issues raised being addressed"

* git://git.kvack.org/~bcrl/aio-next: (22 commits)
  aio: rcu_read_lock protection for new rcu_dereference calls
  aio: fix race in ring buffer page lookup introduced by page migration support
  aio: fix rcu sparse warnings introduced by ioctx table lookup patch
  aio: remove unnecessary debugging from aio_free_ring()
  aio: table lookup: verify ctx pointer
  staging/lustre: kiocb->ki_left is removed
  aio: fix error handling and rcu usage in "convert the ioctx list to table lookup v3"
  aio: be defensive to ensure request batching is non-zero instead of BUG_ON()
  aio: convert the ioctx list to table lookup v3
  aio: double aio_max_nr in calculations
  aio: Kill ki_dtor
  aio: Kill ki_users
  aio: Kill unneeded kiocb members
  aio: Kill aio_rw_vect_retry()
  aio: Don't use ctx->tail unnecessarily
  aio: io_cancel() no longer returns the io_event
  aio: percpu ioctx refcount
  aio: percpu reqs_available
  aio: reqs_active -> reqs_available
  aio: fix build when migration is disabled
  ...

mm: vmscan: fix do_try_to_free_pages() livelock

2013-09-11T22:58:01+00:00

This patch is based on KOSAKI's work and I add a little more description,
please refer https://lkml.org/lkml/2012/6/14/74.

Currently, I found system can enter a state that there are lots of free
pages in a zone but only order-0 and order-1 pages which means the zone is
heavily fragmented, then high order allocation could make direct reclaim
path's long stall(ex, 60 seconds) especially in no swap and no compaciton
enviroment.  This problem happened on v3.4, but it seems issue still lives
in current tree, the reason is do_try_to_free_pages enter live lock:

kswapd will go to sleep if the zones have been fully scanned and are still
not balanced.  As kswapd thinks there's little point trying all over again
to avoid infinite loop.  Instead it changes order from high-order to
0-order because kswapd think order-0 is the most important.  Look at
73ce02e9 in detail.  If watermarks are ok, kswapd will go back to sleep
and may leave zone->all_unreclaimable =3D 0.  It assume high-order users
can still perform direct reclaim if they wish.

Direct reclaim continue to reclaim for a high order which is not a
COSTLY_ORDER without oom-killer until kswapd turn on
zone->all_unreclaimble= .  This is because to avoid too early oom-kill.
So it means direct_reclaim depends on kswapd to break this loop.

In worst case, direct-reclaim may continue to page reclaim forever when
kswapd sleeps forever until someone like watchdog detect and finally kill
the process.  As described in:
http://thread.gmane.org/gmane.linux.kernel.mm/103737

We can't turn on zone->all_unreclaimable from direct reclaim path because
direct reclaim path don't take any lock and this way is racy.  Thus this
patch removes zone->all_unreclaimable field completely and recalculates
zone reclaimable state every time.

Note: we can't take the idea that direct-reclaim see zone->pages_scanned
directly and kswapd continue to use zone->all_unreclaimable.  Because, it
is racy.  commit 929bea7c71 (vmscan: all_unreclaimable() use
zone->all_unreclaimable as a name) describes the detail.

[akpm@linux-foundation.org: uninline zone_reclaimable_pages() and zone_reclaimable()]
Cc: Aaditya Kumar 
Cc: Ying Han 
Cc: Nick Piggin 
Acked-by: Rik van Riel 
Cc: Mel Gorman 
Cc: KAMEZAWA Hiroyuki 
Cc: Christoph Lameter 
Cc: Bob Liu 
Cc: Neil Zhang 
Cc: Russell King - ARM Linux 
Reviewed-by: Michal Hocko 
Acked-by: Minchan Kim 
Acked-by: Johannes Weiner 
Signed-off-by: KOSAKI Motohiro 
Signed-off-by: Lisa Du 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: check movability of hugepage in unmap_and_move_huge_page()

2013-09-11T22:57:49+00:00

Currently hugepage migration works well only for pmd-based hugepages
(mainly due to lack of testing,) so we had better not enable migration of
other levels of hugepages until we are ready for it.

Some users of hugepage migration (mbind, move_pages, and migrate_pages) do
page table walk and check pud/pmd_huge() there, so they are safe.  But the
other users (softoffline and memory hotremove) don't do this, so without
this patch they can try to migrate unexpected types of hugepages.

To prevent this, we introduce hugepage_migration_support() as an
architecture dependent check of whether hugepage are implemented on a pmd
basis or not.  And on some architecture multiple sizes of hugepages are
available, so hugepage_migration_support() also checks hugepage size.

Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Hillf Danton 
Cc: Wanpeng Li 
Cc: Mel Gorman 
Cc: Hugh Dickins 
Cc: KOSAKI Motohiro 
Cc: Michal Hocko 
Cc: Rik van Riel 
Cc: "Aneesh Kumar K.V" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: add hugepage migration code to move_pages()

2013-09-11T22:57:48+00:00

Extend move_pages() to handle vma with VM_HUGETLB set.  We will be able to
migrate hugepage with move_pages(2) after applying the enablement patch
which comes later in this series.

We avoid getting refcount on tail pages of hugepage, because unlike thp,
hugepage is not split and we need not care about races with splitting.

And migration of larger (1GB for x86_64) hugepage are not enabled.

Signed-off-by: Naoya Horiguchi 
Acked-by: Andi Kleen 
Reviewed-by: Wanpeng Li 
Cc: Hillf Danton 
Cc: Mel Gorman 
Cc: Hugh Dickins 
Cc: KOSAKI Motohiro 
Cc: Michal Hocko 
Cc: Rik van Riel 
Cc: "Aneesh Kumar K.V" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: soft-offline: use migrate_pages() instead of migrate_huge_page()

2013-09-11T22:57:47+00:00

Currently migrate_huge_page() takes a pointer to a hugepage to be migrated
as an argument, instead of taking a pointer to the list of hugepages to be
migrated.  This behavior was introduced in commit 189ebff28 ("hugetlb:
simplify migrate_huge_page()"), and was OK because until now hugepage
migration is enabled only for soft-offlining which migrates only one
hugepage in a single call.

But the situation will change in the later patches in this series which
enable other users of page migration to support hugepage migration.  They
can kick migration for both of normal pages and hugepages in a single
call, so we need to go back to original implementation which uses linked
lists to collect the hugepages to be migrated.

With this patch, soft_offline_huge_page() switches to use migrate_pages(),
and migrate_huge_page() is not used any more.  So let's remove it.

Signed-off-by: Naoya Horiguchi 
Acked-by: Andi Kleen 
Reviewed-by: Wanpeng Li 
Acked-by: Hillf Danton 
Cc: Mel Gorman 
Cc: Hugh Dickins 
Cc: KOSAKI Motohiro 
Cc: Michal Hocko 
Cc: Rik van Riel 
Cc: "Aneesh Kumar K.V" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: make core migration code aware of hugepage

2013-09-11T22:57:46+00:00

Currently hugepage migration is available only for soft offlining, but
it's also useful for some other users of page migration (clearly because
users of hugepage can enjoy the benefit of mempolicy and memory hotplug.)
So this patchset tries to extend such users to support hugepage migration.

The target of this patchset is to enable hugepage migration for NUMA
related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and
memory hotplug.

This patchset does not add hugepage migration for memory compaction,
because users of memory compaction mainly expect to construct thp by
arranging raw pages, and there's little or no need to compact hugepages.
CMA, another user of page migration, can have benefit from hugepage
migration, but is not enabled to support it for now (just because of lack
of testing and expertise in CMA.)

Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in
x86_64, or hugepages in architectures like ia64) is not enabled for now
(again, because of lack of testing.)

As for how these are achived, I extended the API (migrate_pages()) to
handle hugepage (with patch 1 and 2) and adjusted code of each caller to
check and collect movable hugepages (with patch 3-7).  Remaining 2 patches
are kind of miscellaneous ones to avoid unexpected behavior.  Patch 8 is
about making sure that we only migrate pmd-based hugepages.  And patch 9
is about choosing appropriate zone for hugepage allocation.

My test is mainly functional one, simply kicking hugepage migration via
each entry point and confirm that migration is done correctly.  Test code
is available here:

  git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git

And I always run libhugetlbfs test when changing hugetlbfs's code.  With
this patchset, no regression was found in the test.

This patch (of 9):

Before enabling each user of page migration to support hugepage,
this patch enables the list of pages for migration to link not only
LRU pages, but also hugepages. As a result, putback_movable_pages()
and migrate_pages() can handle both of LRU pages and hugepages.

Signed-off-by: Naoya Horiguchi 
Acked-by: Andi Kleen 
Reviewed-by: Wanpeng Li 
Acked-by: Hillf Danton 
Cc: Mel Gorman 
Cc: Hugh Dickins 
Cc: KOSAKI Motohiro 
Cc: Michal Hocko 
Cc: Rik van Riel 
Cc: "Aneesh Kumar K.V" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/aio: Add support to aio ring pages migration

2013-07-16T13:32:18+00:00

As the aio job will pin the ring pages, that will lead to mem migrated
failed. In order to fix this problem we use an anon inode to manage the aio ring
pages, and  setup the migratepage callback in the anon inode's address space, so
that when mem migrating the aio ring pages will be moved to other mem node safely.

Signed-off-by: Gu Zheng 
Signed-off-by: Benjamin LaHaise