linux.git/mm/Kconfig, branch v3.11

zswap: add to mm/

2013-07-11T01:11:34+00:00

zswap is a thin backend for frontswap that takes pages that are in the
process of being swapped out and attempts to compress them and store
them in a RAM-based memory pool.  This can result in a significant I/O
reduction on the swap device and, in the case where decompressing from
RAM is faster than reading from the swap device, can also improve
workload performance.

It also has support for evicting swap pages that are currently
compressed in zswap to the swap device on an LRU(ish) basis.  This
functionality makes zswap a true cache in that, once the cache is full,
the oldest pages can be moved out of zswap to the swap device so newer
pages can be compressed and stored in zswap.

This patch adds the zswap driver to mm/

Signed-off-by: Seth Jennings 
Acked-by: Rik van Riel 
Cc: Greg Kroah-Hartman 
Cc: Nitin Gupta 
Cc: Minchan Kim 
Cc: Konrad Rzeszutek Wilk 
Cc: Dan Magenheimer 
Cc: Robert Jennings 
Cc: Jenifer Hopper 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Cc: Larry Woodman 
Cc: Benjamin Herrenschmidt 
Cc: Dave Hansen 
Cc: Joe Perches 
Cc: Joonsoo Kim 
Cc: Cody P Schafer 
Cc: Hugh Dickens 
Cc: Paul Mackerras 
Cc: Fengguang Wu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zbud: add to mm/

2013-07-11T01:11:34+00:00

zbud is an special purpose allocator for storing compressed pages.  It
is designed to store up to two compressed pages per physical page.
While this design limits storage density, it has simple and
deterministic reclaim properties that make it preferable to a higher
density approach when reclaim will be used.

zbud works by storing compressed pages, or "zpages", together in pairs
in a single memory page called a "zbud page".  The first buddy is "left
justifed" at the beginning of the zbud page, and the last buddy is
"right justified" at the end of the zbud page.  The benefit is that if
either buddy is freed, the freed buddy space, coalesced with whatever
slack space that existed between the buddies, results in the largest
possible free region within the zbud page.

zbud also provides an attractive lower bound on density.  The ratio of
zpages to zbud pages can not be less than 1.  This ensures that zbud can
never "do harm" by using more pages to store zpages than the
uncompressed zpages would have used on their own.

This implementation is a rewrite of the zbud allocator internally used
by zcache in the driver/staging tree.  The rewrite was necessary to
remove some of the zcache specific elements that were ingrained
throughout and provide a generic allocation interface that can later be
used by zsmalloc and others.

This patch adds zbud to mm/ for later use by zswap.

Signed-off-by: Seth Jennings 
Acked-by: Rik van Riel 
Cc: Greg Kroah-Hartman 
Cc: Nitin Gupta 
Cc: Minchan Kim 
Cc: Konrad Rzeszutek Wilk 
Cc: Dan Magenheimer 
Cc: Robert Jennings 
Cc: Jenifer Hopper 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Cc: Larry Woodman 
Cc: Benjamin Herrenschmidt 
Cc: Dave Hansen 
Cc: Joe Perches 
Cc: Joonsoo Kim 
Cc: Cody P Schafer 
Cc: Hugh Dickens 
Cc: Paul Mackerras 
Cc: Bob Liu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: soft-dirty bits for user memory changes tracking

2013-07-03T23:07:26+00:00

The soft-dirty is a bit on a PTE which helps to track which pages a task
writes to.  In order to do this tracking one should

  1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs)
  2. Wait some time.
  3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries)

To do this tracking, the writable bit is cleared from PTEs when the
soft-dirty bit is.  Thus, after this, when the task tries to modify a
page at some virtual address the #PF occurs and the kernel sets the
soft-dirty bit on the respective PTE.

Note, that although all the task's address space is marked as r/o after
the soft-dirty bits clear, the #PF-s that occur after that are processed
fast.  This is so, since the pages are still mapped to physical memory,
and thus all the kernel does is finds this fact out and puts back
writable, dirty and soft-dirty bits on the PTE.

Another thing to note, is that when mremap moves PTEs they are marked
with soft-dirty as well, since from the user perspective mremap modifies
the virtual memory at mremap's new address.

Signed-off-by: Pavel Emelyanov 
Cc: Matt Mackall 
Cc: Xiao Guangrong 
Cc: Glauber Costa 
Cc: Marcelo Tosatti 
Cc: KOSAKI Motohiro 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Finally eradicate CONFIG_HOTPLUG

2013-06-03T21:20:18+00:00

Ever since commit 45f035ab9b8f ("CONFIG_HOTPLUG should be always on"),
it has been basically impossible to build a kernel with CONFIG_HOTPLUG
turned off.  Remove all the remaining references to it.

Cc: Russell King 
Cc: Doug Thompson 
Cc: Bjorn Helgaas 
Cc: Steven Whitehouse 
Cc: Arnd Bergmann 
Cc: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: Andrew Morton 
Signed-off-by: Stephen Rothwell 
Acked-by: Mauro Carvalho Chehab 
Acked-by: Hans Verkuil 
Signed-off-by: Greg Kroah-Hartman

mmKconfig: add an option to disable bounce

2013-04-29T22:54:40+00:00

There are times when HIGHMEM is enabled, but we don't prefer
CONFIG_BOUNCE to be enabled.  CONFIG_BOUNCE can reduce the block device
throughput, and this is not ideal for machines where we don't gain much
by enabling it.  So provide an option to deselect CONFIG_BOUNCE.  The
observation was made while measuring eMMC throughput using iozone on an
ARM device with 1GB RAM.

Signed-off-by: Vinayak Menon 
Cc: David Rientjes 
Cc: Jens Axboe 
Cc: Randy Dunlap 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Select VIRT_TO_BUS directly where needed

2013-03-12T18:16:40+00:00

In commit 887cbce0adea ("arch Kconfig: centralise ARCH_NO_VIRT_TO_BUS")
I introduced the config sybmol HAVE_VIRT_TO_BUS and selected that where
needed.  I am not sure what I was thinking.  Instead, just directly
select VIRT_TO_BUS where it is needed.

Signed-off-by: Stephen Rothwell 
Signed-off-by: Linus Torvalds

arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS

2013-02-28T03:10:23+00:00

Change it to CONFIG_HAVE_VIRT_TO_BUS and set it in all architecures
that already provide virt_to_bus().

Signed-off-by: Stephen Rothwell 
Reviewed-by: James Hogan 
Cc: Bjorn Helgaas 
Cc: H Hartley Sweeten 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: "David S. Miller" 
Cc: Paul Mundt 
Cc: Vineet Gupta 
Cc: James Bottomley 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memory-hotplug: implement register_page_bootmem_info_section of sparse-vmemmap

2013-02-24T01:50:12+00:00

For removing memmap region of sparse-vmemmap which is allocated bootmem,
memmap region of sparse-vmemmap needs to be registered by
get_page_bootmem().  So the patch searches pages of virtual mapping and
registers the pages by get_page_bootmem().

NOTE: register_page_bootmem_memmap() is not implemented for ia64,
      ppc, s390, and sparc.  So introduce CONFIG_HAVE_BOOTMEM_INFO_NODE
      and revert register_page_bootmem_info_node() when platform doesn't
      support it.

      It's implemented by adding a new Kconfig option named
      CONFIG_HAVE_BOOTMEM_INFO_NODE, which will be automatically selected
      by memory-hotplug feature fully supported archs(currently only on
      x86_64).

      Since we have 2 config options called MEMORY_HOTPLUG and
      MEMORY_HOTREMOVE used for memory hot-add and hot-remove separately,
      and codes in function register_page_bootmem_info_node() are only
      used for collecting infomation for hot-remove, so reside it under
      MEMORY_HOTREMOVE.

      Besides page_isolation.c selected by MEMORY_ISOLATION under
      MEMORY_HOTPLUG is also such case, move it too.

[mhocko@suse.cz: put register_page_bootmem_memmap inside CONFIG_MEMORY_HOTPLUG_SPARSE]
[linfeng@cn.fujitsu.com: introduce CONFIG_HAVE_BOOTMEM_INFO_NODE and revert register_page_bootmem_info_node()]
[mhocko@suse.cz: remove the arch specific functions without any implementation]
[linfeng@cn.fujitsu.com: mm/Kconfig: move auto selects from MEMORY_HOTPLUG to MEMORY_HOTREMOVE as needed]
[rientjes@google.com: fix defined but not used warning]
Signed-off-by: Wen Congyang 
Signed-off-by: Yasuaki Ishimatsu 
Signed-off-by: Tang Chen 
Reviewed-by: Wu Jianguo 
Cc: KOSAKI Motohiro 
Cc: Jiang Liu 
Cc: Jianguo Wu 
Cc: Kamezawa Hiroyuki 
Cc: Lai Jiangshan 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Signed-off-by: Michal Hocko 
Signed-off-by: Lin Feng 
Signed-off-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (incoming from Andrew)

2013-02-22T01:38:49+00:00

Merge misc patches from Andrew Morton:

 - Florian has vanished so I appear to have become fbdev maintainer
   again :(

 - Joel and Mark are distracted to welcome to the new OCFS2 maintainer

 - The backlight queue

 - Small core kernel changes

 - lib/ updates

 - The rtc queue

 - Various random bits

* akpm: (164 commits)
  rtc: rtc-davinci: use devm_*() functions
  rtc: rtc-max8997: use devm_request_threaded_irq()
  rtc: rtc-max8907: use devm_request_threaded_irq()
  rtc: rtc-da9052: use devm_request_threaded_irq()
  rtc: rtc-wm831x: use devm_request_threaded_irq()
  rtc: rtc-tps80031: use devm_request_threaded_irq()
  rtc: rtc-lp8788: use devm_request_threaded_irq()
  rtc: rtc-coh901331: use devm_clk_get()
  rtc: rtc-vt8500: use devm_*() functions
  rtc: rtc-tps6586x: use devm_request_threaded_irq()
  rtc: rtc-imxdi: use devm_clk_get()
  rtc: rtc-cmos: use dev_warn()/dev_dbg() instead of printk()/pr_debug()
  rtc: rtc-pcf8583: use dev_warn() instead of printk()
  rtc: rtc-sun4v: use pr_warn() instead of printk()
  rtc: rtc-vr41xx: use dev_info() instead of printk()
  rtc: rtc-rs5c313: use pr_err() instead of printk()
  rtc: rtc-at91rm9200: use dev_dbg()/dev_err() instead of printk()/pr_debug()
  rtc: rtc-rs5c372: use dev_dbg()/dev_warn() instead of printk()/pr_debug()
  rtc: rtc-ds2404: use dev_err() instead of printk()
  rtc: rtc-efi: use dev_err()/dev_warn()/pr_err() instead of printk()
  ...

block: optionally snapshot page contents to provide stable pages during write

2013-02-22T01:22:20+00:00

This provides a band-aid to provide stable page writes on jbd without
needing to backport the fixed locking and page writeback bit handling
schemes of jbd2.  The band-aid works by using bounce buffers to snapshot
page contents instead of waiting.

For those wondering about the ext3 bandage -- fixing the jbd locking
(which was done as part of ext4dev years ago) is a lot of surgery, and
setting PG_writeback on data pages when we actually hold the page lock
dropped ext3 performance by nearly an order of magnitude.  If we're
going to migrate iscsi and raid to use stable page writes, the
complaints about high latency will likely return.  We might as well
centralize their page snapshotting thing to one place.

Signed-off-by: Darrick J. Wong 
Tested-by: Andy Lutomirski 
Cc: Adrian Hunter 
Cc: Artem Bityutskiy 
Reviewed-by: Jan Kara 
Cc: Joel Becker 
Cc: Mark Fasheh 
Cc: Steven Whitehouse 
Cc: Jens Axboe 
Cc: Eric Van Hensbergen 
Cc: Ron Minnich 
Cc: Latchesar Ionkov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds