linux-toradex.git/Documentation/vm, branch v4.8-rc1

Merge tag 'doc-4.8-fixes' of git://git.lwn.net/linux

2016-08-07T14:23:17+00:00

Pull documentation fixes from Jonathan Corbet:
 "Three fixes for the docs build, including removing an annoying warning
  on 'make help' if sphinx isn't present"

* tag 'doc-4.8-fixes' of git://git.lwn.net/linux:
  DocBook: use DOCBOOKS="" to ignore DocBooks instead of IGNORE_DOCBOOKS=1
  Documenation: update cgroup's document path
  Documentation/sphinx: do not warn about missing tools in 'make help'

Documenation: update cgroup's document path

2016-08-03T21:43:58+00:00

cgroup's document path is changed to "cgroup-v1". update it.

Signed-off-by: seokhoon.yoon 
Signed-off-by: Jonathan Corbet

mm: fix build warnings in

2016-07-26T23:19:19+00:00

Randy reported below build error.

> In file included from ../include/linux/balloon_compaction.h:48:0,
>                  from ../mm/balloon_compaction.c:11:
> ../include/linux/compaction.h:237:51: warning: 'struct node' declared inside parameter list [enabled by default]
>  static inline int compaction_register_node(struct node *node)
> ../include/linux/compaction.h:237:51: warning: its scope is only this definition or declaration, which is probably not what you want [enabled by default]
> ../include/linux/compaction.h:242:54: warning: 'struct node' declared inside parameter list [enabled by default]
>  static inline void compaction_unregister_node(struct node *node)
>

It was caused by non-lru page migration which needs compaction.h but
compaction.h doesn't include any header to be standalone.

I think proper header for non-lru page migration is migrate.h rather
than compaction.h because migrate.h has already headers needed to work
non-lru page migration indirectly like isolate_mode_t, migrate_mode
MIGRATEPAGE_SUCCESS.

[akpm@linux-foundation.org: revert mm-balloon-use-general-non-lru-movable-page-feature-fix.patch temp fix]
Link: http://lkml.kernel.org/r/20160610003304.GE29779@bbox
Signed-off-by: Minchan Kim 
Reported-by: Randy Dunlap 
Cc: Konstantin Khlebnikov 
Cc: Vlastimil Babka 
Cc: Gioh Kim 
Cc: Rafael Aquini 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: update Documentation/{vm/transhuge,filesystems/proc}.txt

2016-07-26T23:19:19+00:00

Add info about tmpfs/shmem with huge pages.

Link: http://lkml.kernel.org/r/1466021202-61880-38-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp, mlock: update unevictable-lru.txt

2016-07-26T23:19:19+00:00

Add description of THP handling into unevictable-lru.txt.

Link: http://lkml.kernel.org/r/1466021202-61880-7-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: support non-lru movable page migration

2016-07-26T23:19:19+00:00

We have allowed migration for only LRU pages until now and it was enough
to make high-order pages.  But recently, embedded system(e.g., webOS,
android) uses lots of non-movable pages(e.g., zram, GPU memory) so we
have seen several reports about troubles of small high-order allocation.
For fixing the problem, there were several efforts (e,g,.  enhance
compaction algorithm, SLUB fallback to 0-order page, reserved memory,
vmalloc and so on) but if there are lots of non-movable pages in system,
their solutions are void in the long run.

So, this patch is to support facility to change non-movable pages with
movable.  For the feature, this patch introduces functions related to
migration to address_space_operations as well as some page flags.

If a driver want to make own pages movable, it should define three
functions which are function pointers of struct
address_space_operations.

1. bool (*isolate_page) (struct page *page, isolate_mode_t mode);

What VM expects on isolate_page function of driver is to return *true*
if driver isolates page successfully.  On returing true, VM marks the
page as PG_isolated so concurrent isolation in several CPUs skip the
page for isolation.  If a driver cannot isolate the page, it should
return *false*.

Once page is successfully isolated, VM uses page.lru fields so driver
shouldn't expect to preserve values in that fields.

2. int (*migratepage) (struct address_space *mapping,
		struct page *newpage, struct page *oldpage, enum migrate_mode);

After isolation, VM calls migratepage of driver with isolated page.  The
function of migratepage is to move content of the old page to new page
and set up fields of struct page newpage.  Keep in mind that you should
indicate to the VM the oldpage is no longer movable via
__ClearPageMovable() under page_lock if you migrated the oldpage
successfully and returns 0.  If driver cannot migrate the page at the
moment, driver can return -EAGAIN.  On -EAGAIN, VM will retry page
migration in a short time because VM interprets -EAGAIN as "temporal
migration failure".  On returning any error except -EAGAIN, VM will give
up the page migration without retrying in this time.

Driver shouldn't touch page.lru field VM using in the functions.

3. void (*putback_page)(struct page *);

If migration fails on isolated page, VM should return the isolated page
to the driver so VM calls driver's putback_page with migration failed
page.  In this function, driver should put the isolated page back to the
own data structure.

4. non-lru movable page flags

There are two page flags for supporting non-lru movable page.

* PG_movable

Driver should use the below function to make page movable under
page_lock.

	void __SetPageMovable(struct page *page, struct address_space *mapping)

It needs argument of address_space for registering migration family
functions which will be called by VM.  Exactly speaking, PG_movable is
not a real flag of struct page.  Rather than, VM reuses page->mapping's
lower bits to represent it.

	#define PAGE_MAPPING_MOVABLE 0x2
	page->mapping = page->mapping | PAGE_MAPPING_MOVABLE;

so driver shouldn't access page->mapping directly.  Instead, driver
should use page_mapping which mask off the low two bits of page->mapping
so it can get right struct address_space.

For testing of non-lru movable page, VM supports __PageMovable function.
However, it doesn't guarantee to identify non-lru movable page because
page->mapping field is unified with other variables in struct page.  As
well, if driver releases the page after isolation by VM, page->mapping
doesn't have stable value although it has PAGE_MAPPING_MOVABLE (Look at
__ClearPageMovable).  But __PageMovable is cheap to catch whether page
is LRU or non-lru movable once the page has been isolated.  Because LRU
pages never can have PAGE_MAPPING_MOVABLE in page->mapping.  It is also
good for just peeking to test non-lru movable pages before more
expensive checking with lock_page in pfn scanning to select victim.

For guaranteeing non-lru movable page, VM provides PageMovable function.
Unlike __PageMovable, PageMovable functions validates page->mapping and
mapping->a_ops->isolate_page under lock_page.  The lock_page prevents
sudden destroying of page->mapping.

Driver using __SetPageMovable should clear the flag via
__ClearMovablePage under page_lock before the releasing the page.

* PG_isolated

To prevent concurrent isolation among several CPUs, VM marks isolated
page as PG_isolated under lock_page.  So if a CPU encounters PG_isolated
non-lru movable page, it can skip it.  Driver doesn't need to manipulate
the flag because VM will set/clear it automatically.  Keep in mind that
if driver sees PG_isolated page, it means the page have been isolated by
VM so it shouldn't touch page.lru field.  PG_isolated is alias with
PG_reclaim flag so driver shouldn't use the flag for own purpose.

[opensource.ganesh@gmail.com: mm/compaction: remove local variable is_lru]
  Link: http://lkml.kernel.org/r/20160618014841.GA7422@leo-test
Link: http://lkml.kernel.org/r/1464736881-24886-3-git-send-email-minchan@kernel.org
Signed-off-by: Gioh Kim 
Signed-off-by: Minchan Kim 
Signed-off-by: Ganesh Mahendran 
Acked-by: Vlastimil Babka 
Cc: Sergey Senozhatsky 
Cc: Rik van Riel 
Cc: Joonsoo Kim 
Cc: Mel Gorman 
Cc: Hugh Dickins 
Cc: Rafael Aquini 
Cc: Jonathan Corbet 
Cc: John Einar Reitan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

z3fold: the 3-fold allocator for compressed pages

2016-05-21T00:58:30+00:00

This patch introduces z3fold, a special purpose allocator for storing
compressed pages.  It is designed to store up to three compressed pages
per physical page.  It is a ZBUD derivative which allows for higher
compression ratio keeping the simplicity and determinism of its
predecessor.

This patch comes as a follow-up to the discussions at the Embedded Linux
Conference in San-Diego related to the talk [1].  The outcome of these
discussions was that it would be good to have a compressed page
allocator as stable and deterministic as zbud with with higher
compression ratio.

To keep the determinism and simplicity, z3fold, just like zbud, always
stores an integral number of compressed pages per page, but it can store
up to 3 pages unlike zbud which can store at most 2.  Therefore the
compression ratio goes to around 2.6x while zbud's one is around 1.7x.

The patch is based on the latest linux.git tree.

This version has been updated after testing on various simulators (e.g.
ARM Versatile Express, MIPS Malta, x86_64/Haswell) and basing on
comments from Dan Streetman [3].

[1] https://openiotelc2016.sched.org/event/6DAC/swapping-and-embedded-compression-relieves-the-pressure-vitaly-wool-softprise-consulting-ou
[2] https://lkml.org/lkml/2016/4/21/799
[3] https://lkml.org/lkml/2016/5/4/852

Link: http://lkml.kernel.org/r/20160509151753.ec3f9fda3c9898d31ff52a32@gmail.com
Signed-off-by: Vitaly Wool 
Cc: Seth Jennings 
Cc: Dan Streetman 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: vm: fix spelling mistakes

2016-05-21T00:58:30+00:00

Signed-off-by: Eric Engestrom 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2016-05-20T03:00:06+00:00

Merge updates from Andrew Morton:

 - fsnotify fix

 - poll() timeout fix

 - a few scripts/ tweaks

 - debugobjects updates

 - the (small) ocfs2 queue

 - Minor fixes to kernel/padata.c

 - Maybe half of the MM queue

* emailed patches from Andrew Morton : (117 commits)
  mm, page_alloc: restore the original nodemask if the fast path allocation failed
  mm, page_alloc: uninline the bad page part of check_new_page()
  mm, page_alloc: don't duplicate code in free_pcp_prepare
  mm, page_alloc: defer debugging checks of pages allocated from the PCP
  mm, page_alloc: defer debugging checks of freed pages until a PCP drain
  cpuset: use static key better and convert to new API
  mm, page_alloc: inline pageblock lookup in page free fast paths
  mm, page_alloc: remove unnecessary variable from free_pcppages_bulk
  mm, page_alloc: pull out side effects from free_pages_check
  mm, page_alloc: un-inline the bad part of free_pages_check
  mm, page_alloc: check multiple page fields with a single branch
  mm, page_alloc: remove field from alloc_context
  mm, page_alloc: avoid looking up the first zone in a zonelist twice
  mm, page_alloc: shortcut watermark checks for order-0 pages
  mm, page_alloc: reduce cost of fair zone allocation policy retry
  mm, page_alloc: shorten the page allocator fast path
  mm, page_alloc: check once if a zone has isolated pageblocks
  mm, page_alloc: move __GFP_HARDWALL modifications out of the fastpath
  mm, page_alloc: simplify last cpupid reset
  mm, page_alloc: remove unnecessary initialisation from __alloc_pages_nodemask()
  ...

mm: rename _count, field of the struct page, to _refcount

2016-05-20T02:12:14+00:00

Many developers already know that field for reference count of the
struct page is _count and atomic type.  They would try to handle it
directly and this could break the purpose of page reference count
tracepoint.  To prevent direct _count modification, this patch rename it
to _refcount and add warning message on the code.  After that, developer
who need to handle reference count will find that field should not be
accessed directly.

[akpm@linux-foundation.org: fix comments, per Vlastimil]
[akpm@linux-foundation.org: Documentation/vm/transhuge.txt too]
[sfr@canb.auug.org.au: sync ethernet driver changes]
Signed-off-by: Joonsoo Kim 
Signed-off-by: Stephen Rothwell 
Cc: Vlastimil Babka 
Cc: Hugh Dickins 
Cc: Johannes Berg 
Cc: "David S. Miller" 
Cc: Sunil Goutham 
Cc: Chris Metcalf 
Cc: Manish Chopra 
Cc: Yuval Mintz 
Cc: Tariq Toukan 
Cc: Saeed Mahameed 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds