linux-toradex.git/mm/swap.c, branch v3.2.26

mm: fix UP THP spin_is_locked BUGs

2012-02-13T19:17:01+00:00

commit b9980cdcf2524c5fe15d8cbae9c97b3ed6385563 upstream.

Fix CONFIG_TRANSPARENT_HUGEPAGE=y CONFIG_SMP=n CONFIG_DEBUG_VM=y
CONFIG_DEBUG_SPINLOCK=n kernel: spin_is_locked() is then always false,
and so triggers some BUGs in Transparent HugePage codepaths.

asm-generic/bug.h mentions this problem, and provides a WARN_ON_SMP(x);
but being too lazy to add VM_BUG_ON_SMP, BUG_ON_SMP, WARN_ON_SMP_ONCE,
VM_WARN_ON_SMP_ONCE, just test NR_CPUS != 1 in the existing VM_BUG_ONs.

Signed-off-by: Hugh Dickins 
Cc: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

2011-11-07T03:44:47+00:00

* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
  Revert "tracing: Include module.h in define_trace.h"
  irq: don't put module.h into irq.h for tracking irqgen modules.
  bluetooth: macroize two small inlines to avoid module.h
  ip_vs.h: fix implicit use of module_get/module_put from module.h
  nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
  include: replace linux/module.h with "struct module" wherever possible
  include: convert various register fcns to macros to avoid include chaining
  crypto.h: remove unused crypto_tfm_alg_modname() inline
  uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
  pm_runtime.h: explicitly requires notifier.h
  linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
  miscdevice.h: fix up implicit use of lists and types
  stop_machine.h: fix implicit use of smp.h for smp_processor_id
  of: fix implicit use of errno.h in include/linux/of.h
  of_platform.h: delete needless include 
  acpi: remove module.h include from platform/aclinux.h
  miscdevice.h: delete unnecessary inclusion of module.h
  device_cgroup.h: delete needless include 
  net: sch_generic remove redundant use of 
  net: inet_timewait_sock doesnt need 
  ...

Fix up trivial conflicts (other header files, and  removal of the ab3550 mfd driver) in
 - drivers/media/dvb/frontends/dibx000_common.c
 - drivers/media/video/{mt9m111.c,ov6650.c}
 - drivers/mfd/ab3550-core.c
 - include/linux/dmaengine.h

mm: thp: tail page refcounting fix

2011-11-02T23:06:57+00:00

Michel while working on the working set estimation code, noticed that
calling get_page_unless_zero() on a random pfn_to_page(random_pfn)
wasn't safe, if the pfn ended up being a tail page of a transparent
hugepage under splitting by __split_huge_page_refcount().

He then found the problem could also theoretically materialize with
page_cache_get_speculative() during the speculative radix tree lookups
that uses get_page_unless_zero() in SMP if the radix tree page is freed
and reallocated and get_user_pages is called on it before
page_cache_get_speculative has a chance to call get_page_unless_zero().

So the best way to fix the problem is to keep page_tail->_count zero at
all times.  This will guarantee that get_page_unless_zero() can never
succeed on any tail page.  page_tail->_mapcount is guaranteed zero and
is unused for all tail pages of a compound page, so we can simply
account the tail page references there and transfer them to
tail_page->_count in __split_huge_page_refcount() (in addition to the
head_page->_mapcount).

While debugging this s/_count/_mapcount/ change I also noticed get_page is
called by direct-io.c on pages returned by get_user_pages.  That wasn't
entirely safe because the two atomic_inc in get_page weren't atomic.  As
opposed to other get_user_page users like secondary-MMU page fault to
establish the shadow pagetables would never call any superflous get_page
after get_user_page returns.  It's safer to make get_page universally safe
for tail pages and to use get_page_foll() within follow_page (inside
get_user_pages()).  get_page_foll() is safe to do the refcounting for tail
pages without taking any locks because it is run within PT lock protected
critical sections (PT lock for pte and page_table_lock for
pmd_trans_huge).

The standard get_page() as invoked by direct-io instead will now take
the compound_lock but still only for tail pages.  The direct-io paths
are usually I/O bound and the compound_lock is per THP so very
finegrined, so there's no risk of scalability issues with it.  A simple
direct-io benchmarks with all lockdep prove locking and spinlock
debugging infrastructure enabled shows identical performance and no
overhead.  So it's worth it.  Ideally direct-io should stop calling
get_page() on pages returned by get_user_pages().  The spinlock in
get_page() is already optimized away for no-THP builds but doing
get_page() on tail pages returned by GUP is generally a rare operation
and usually only run in I/O paths.

This new refcounting on page_tail->_mapcount in addition to avoiding new
RCU critical sections will also allow the working set estimation code to
work without any further complexity associated to the tail page
refcounting with THP.

Signed-off-by: Andrea Arcangeli 
Reported-by: Michel Lespinasse 
Reviewed-by: Michel Lespinasse 
Reviewed-by: Minchan Kim 
Cc: Peter Zijlstra 
Cc: Hugh Dickins 
Cc: Johannes Weiner 
Cc: Rik van Riel 
Cc: Mel Gorman 
Cc: KOSAKI Motohiro 
Cc: Benjamin Herrenschmidt 
Cc: David Gibson 
Cc: 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: Map most files to use export.h instead of module.h

2011-10-31T13:20:12+00:00

The files changed within are only using the EXPORT_SYMBOL
macro variants.  They are not using core modular infrastructure
and hence don't need module.h but only the export.h header.

Signed-off-by: Paul Gortmaker

mm: batch activate_page() to reduce lock contention

2011-05-25T15:39:37+00:00

The zone->lru_lock is heavily contented in workload where activate_page()
is frequently used.  We could do batch activate_page() to reduce the lock
contention.  The batched pages will be added into zone list when the pool
is full or page reclaim is trying to drain them.

For example, in a 4 socket 64 CPU system, create a sparse file and 64
processes, processes shared map to the file.  Each process read access the
whole file and then exit.  The process exit will do unmap_vmas() and cause
a lot of activate_page() call.  In such workload, we saw about 58% total
time reduction with below patch.  Other workloads with a lot of
activate_page also benefits a lot too.

Andrew Morton suggested activate_page() and putback_lru_pages() should
follow the same path to active pages, but this is hard to implement (see
commit 7a608572a282a ("Revert "mm: batch activate_page() to reduce lock
contention")).  On the other hand, do we really need putback_lru_pages()
to follow the same path?  I tested several FIO/FFSB benchmark (about 20
scripts for each benchmark) in 3 machines here from 2 sockets to 4
sockets.  My test doesn't show anything significant with/without below
patch (there is slight difference but mostly some noise which we found
even without below patch before).  Below patch basically returns to the
same as my first post.

I tested some microbenchmarks:
  case-anon-cow-rand-mt         0.58%
  case-anon-cow-rand           -3.30%
  case-anon-cow-seq-mt         -0.51%
  case-anon-cow-seq            -5.68%
  case-anon-r-rand-mt           0.23%
  case-anon-r-rand              0.81%
  case-anon-r-seq-mt           -0.71%
  case-anon-r-seq              -1.99%
  case-anon-rx-rand-mt          2.11%
  case-anon-rx-seq-mt           3.46%
  case-anon-w-rand-mt          -0.03%
  case-anon-w-rand             -0.50%
  case-anon-w-seq-mt           -1.08%
  case-anon-w-seq              -0.12%
  case-anon-wx-rand-mt         -5.02%
  case-anon-wx-seq-mt          -1.43%
  case-fork                     1.65%
  case-fork-sleep              -0.07%
  case-fork-withmem             1.39%
  case-hugetlb                 -0.59%
  case-lru-file-mmap-read-mt   -0.54%
  case-lru-file-mmap-read       0.61%
  case-lru-file-mmap-read-rand -2.24%
  case-lru-file-readonce       -0.64%
  case-lru-file-readtwice     -11.69%
  case-lru-memcg               -1.35%
  case-mmap-pread-rand-mt       1.88%
  case-mmap-pread-rand        -15.26%
  case-mmap-pread-seq-mt        0.89%
  case-mmap-pread-seq         -69.72%
  case-mmap-xread-rand-mt       0.71%
  case-mmap-xread-seq-mt        0.38%

The most significent are:
  case-lru-file-readtwice     -11.69%
  case-mmap-pread-rand        -15.26%
  case-mmap-pread-seq         -69.72%

which use activate_page a lot.  others are basically variations because
each run has slightly difference.

In UP case, 'size mm/swap.o'
before the two patches:
   text    data     bss     dec     hex filename
   6466     896       4    7366    1cc6 mm/swap.o
after the two patches:
   text    data     bss     dec     hex filename
   6343     896       4    7243    1c4b mm/swap.o

Signed-off-by: Shaohua Li 
Cc: KOSAKI Motohiro 
Cc: Hiroyuki Kamezawa 
Cc: Andi Kleen 
Cc: Minchan Kim 
Cc: Rik van Riel 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: filter unevictable page out in deactivate_page()

2011-05-25T15:39:27+00:00

It's pointless that deactive_page's operates on unevictable pages.  This
patch removes unnecessary overhead which might be a bit problem in case
that there are many unevictable page in system(ex, mprotect workload)

[akpm@linux-foundation.org: tidy up comment]
Reviewed-by: KOSAKI Motohiro 
Signed-off-by: Minchan Kim 
Reviewed-by: Rik van Riel
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: check PageUnevictable in lru_deactivate_fn()

2011-05-12T01:50:44+00:00

The lru_deactivate_fn should not move page which in on unevictable lru
into inactive list.  Otherwise, we can meet BUG when we use
isolate_lru_pages as __isolate_lru_page could return -EINVAL.

Reported-by: Ying Han 
Tested-by: Ying Han 
Signed-off-by: Minchan Kim 
Reviewed-by: KOSAKI Motohiro 
Reviewed-by: Rik van Riel
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: simplify code of swap.c

2011-03-23T00:44:09+00:00

Clean up code and remove duplicate code. Next patch will use
pagevec_lru_move_fn introduced here too.

Signed-off-by: Shaohua Li 
Cc: KOSAKI Motohiro 
Cc: Hiroyuki Kamezawa 
Cc: Andi Kleen 
Reviewed-by: Minchan Kim 
Cc: Rik van Riel 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: reclaim invalidated page ASAP

2011-03-23T00:44:04+00:00

invalidate_mapping_pages is very big hint to reclaimer.  It means user
doesn't want to use the page any more.  So in order to prevent working set
page eviction, this patch move the page into tail of inactive list by
PG_reclaim.

Please, remember that pages in inactive list are working set as well as
active list.  If we don't move pages into inactive list's tail, pages near
by tail of inactive list can be evicted although we have a big clue about
useless pages.  It's totally bad.

Now PG_readahead/PG_reclaim is shared.  fe3cba17 added ClearPageReclaim
into clear_page_dirty_for_io for preventing fast reclaiming readahead
marker page.

In this series, PG_reclaim is used by invalidated page, too.  If VM find
the page is invalidated and it's dirty, it sets PG_reclaim to reclaim
asap.  Then, when the dirty page will be writeback,
clear_page_dirty_for_io will clear PG_reclaim unconditionally.  It
disturbs this serie's goal.

I think it's okay to clear PG_readahead when the page is dirty, not
writeback time.  So this patch moves ClearPageReadahead.  In v4,
ClearPageReadahead in set_page_dirty has a problem which is reported by
Steven Barrett.  It's due to compound page.  Some driver(ex, audio) calls
set_page_dirty with compound page which isn't on LRU.  but my patch does
ClearPageRelcaim on compound page.  In non-CONFIG_PAGEFLAGS_EXTENDED, it
breaks PageTail flag.

I think it doesn't affect THP and pass my test with THP enabling but Cced
Andrea for double check.

Signed-off-by: Minchan Kim 
Reported-by: Steven Barrett 
Reviewed-by: Johannes Weiner 
Acked-by: Rik van Riel 
Acked-by: Mel Gorman 
Cc: Wu Fengguang 
Cc: KOSAKI Motohiro 
Cc: Nick Piggin 
Cc: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: move memcg reclaimable page into tail of inactive list

2011-03-23T00:44:03+00:00

The rotate_reclaimable_page function moves just written out pages, which
the VM wanted to reclaim, to the end of the inactive list.  That way the
VM will find those pages first next time it needs to free memory.

This patch applies the rule in memcg.  It can help to prevent unnecessary
working page eviction of memcg.

Signed-off-by: Minchan Kim 
Acked-by: Balbir Singh 
Acked-by: KAMEZAWA Hiroyuki 
Reviewed-by: Rik van Riel 
Cc: KOSAKI Motohiro 
Acked-by: Johannes Weiner 
Cc: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds