mm: remove compressed copy from zram in-memory

Swap subsystem does lazy swap slot free with expecting the page would be
swapped out again so we can avoid unnecessary write.

But the problem in in-memory swap(ex, zram) is that it consumes memory
space until vm_swap_full(ie, used half of all of swap device) condition
meet.  It could be bad if we use multiple swap device, small in-memory
swap and big storage swap or in-memory swap alone.

This patch makes swap subsystem free swap slot as soon as swap-read is
completed and make the swapcache page dirty so the page should be
written out the swap device to reclaim it.  It means we never lose it.

I tested this patch with kernel compile workload.

1. before

   compile time : 9882.42
   zram max wasted space by fragmentation: 13471881 byte
   memory space consumed by zram: 174227456 byte
   the number of slot free notify: 206684

2. after

   compile time : 9653.90
   zram max wasted space by fragmentation: 11805932 byte
   memory space consumed by zram: 154001408 byte
   the number of slot free notify: 426972

[akpm@linux-foundation.org: tweak comment text]
[artem.savkov@gmail.com: fix BUG due to non-swapcache pages in end_swap_bio_read()]
[akpm@linux-foundation.org: invert unlikely() test, augment comment, 80-col cleanup]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Artem Savkov <artem.savkov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Konrad Rzeszutek Wilk <konrad@darnok.org>
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Change-Id: I8f11fb7f0391954435002e7f290352f311c907d4

Signed-off-by: Paul Reioux <reioux@gmail.com>
deadline: Allow 0ms deadline latency, increase the read speed

Change a timer compare from after to after-equals, thus allowing
0 timeout and making deadline schedule FIFO.

Signed-off-by: xiaobing tu <xiaobing.tu@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
[PATCH, v9] cgroups: introduce timer slack controller

Changelog:

v9:
 - update documentation
 - minor cleanup
v8:
 - change hiearchy rules
 - introduce timer_slack.effective_slack_ns
 - get_task_timer_slack() -> task_get_effective_timer_slack()
 - task_get_effective_timer_slack() splited in separate patch
 - implement PR_GET_EFFECTIVE_TIMERSLACK
v7:
 - totally reworked interface and rewritten from scratch
   (See Documentation/cgroups/timer_slack.txt for more information)
v6:
 - add documentation
 - use notifier_call_chain() instead of check hook
 - fix validate_change()
 - cleanup
v5:
 - -EBUSY on writing to timer_slack.min_slack_ns/max_slack_ns if a child has
   wider min-max range
v4:
 - hierarchy support
 - drop dummy_timer_slack_check()
 - workaround lockdep false (?) positive
 - allow 0 as timer slack value
v3:
 - rework interface
 - s/EXPORT_SYMBOL/EXPORT_SYMBOL_GPL/
v2:
 - fixed with CONFIG_CGROUP_TIMER_SLACK=y
v1:
 - initial revision

---

[PATCH, v9 1/3] hrtimer: introduce effective timer slack

task_get_effective_timer_slack() returns timer slack value to be used
to configure per-task timers. It can be equal or higher than task's
timer slack value.

For now task_get_effective_timer_slack() returns timer_slack_ns of the
task. Timer slack cgroup controller will implement a bit more
sophisticated logic.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

---

[PATCH, v9 2/3] hrtimer: implement PR_GET_EFFECTIVE_TIMERSLACK

PR_GET_EFFECTIVE_TIMERSLACK allows process to know its effective timer
slack value.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

---

[PATCH, v9 3/3] cgroups: introduce timer slack controller

Every task_struct has timer_slack_ns value. This value uses to round up
poll() and select() timeout values. This feature can be useful in
mobile environment where combined wakeups are desired.

Originally, prctl() was the only way to change timer slack value of
a process. So you was not able change timer slack value of another
process.

cgroup subsys "timer_slack" implements timer slack controller. It
provides a way to set minimal timer slack value for a group of tasks.
If a task belongs to a cgroup with minimal timer slack value higher than
task's value, cgroup's value will be applied.

Timer slack controller allows to implement setting timer slack value of
a process based on a policy. For example, you can create foreground and
background cgroups and move tasks between them based on system state.

Idea-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

---

kernel/cgroup_timer_slack.c: fix compile error

kernel/cgroup_timer_slack.c:41: error: implicit declaration of
function 'ERR_PTR'

Signed-off-by: Boy Petersen <boypetersen@gmail.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>

Conflicts:

	include/linux/cgroup_subsys.h

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>

Conflicts:

	include/linux/cgroup_subsys.h

Change-Id: Ia2ee98cdd3e45e80cbd93026390f17c446b19cec
cgroup/timer_slack: fix cgroup permission errors

Since the common mounting of cpu and timer_slack into /dev/cpuctl
in commit
https://github.com/boype/kernel_tuna_jb42/commit/f23ab456002c2d3b416260862dbfdb82b031a450
the Android OS cannot move processes across cgoups anymore:

    W/SchedPolicy( 1180): add_tid_to_cgroup failed to write '5949'
    (Permission denied); policy=0

Fix this by implementing an 'allow_attach' handler, according to
this commit:
https://github.com/boype/kernel_tuna_jb42/commit/bb5b603036b99d80527b222dc98eba4ee8341020

Signed-off-by: Boy Petersen <boypetersen@gmail.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
dt: add helper functions to read u32 and string property values

Add helper functions to retrieve unsigned integer and string property
values from properties of a device node. These helper functions can be
used to lookup a property in a device node, perform error checking and
read the property value.

[grant.likely@secretlab.ca: Proposal and initial implementation]
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
[grant.likely: some word smithing and be more defensive validating the string]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Conflicts:

	include/linux/of.h

Change-Id: I2efb1a77c5d5b1e43aafb846c4fd553f7d8cd525
dt: add 'const' for of_property_read_string parameter **out_string

The existing dt codes usually call of_get_property to get a string
property and save it as a 'const char *'.  The patch adds'const' for
of_property_read_string parameter **out_string to make the converting
of existing code a little easier.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
dt: add helper function to read u32 arrays

Rework of_property_read_u32 to read an array of values. Then
of_property_read_u32 becomes an inline with array size of 1.

Also make struct device_node ptr const.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Conflicts:

	include/linux/of.h

Change-Id: I070cafaf9c115c848d076fe6a962bccb8fe10c13
of: constify property name parameters for helper functions

The helper functions for reading u32 integers, u32 arrays and strings
should have the property name as a const pointer.

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
decompressor: Add LZ4 decompressor module

Date	Tue, 26 Feb 2013 15:24:27 +0900

This patch adds support for LZ4 decompression in the Linux Kernel.
LZ4 Decompression APIs for kernel are based on LZ4 implementation
by Yann Collet.

LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
LZ4 source repository : http://code.google.com/p/lz4/

Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>

v2:
- Clean up code
- Enable unaligned access for ARM v6 and above with
  CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
- Add lz4_decompress() for faster decompression with
  uncompressed output size

Signed-off-by: Paul Reioux <reioux@gmail.com>
lib: Add support for LZ4-compressed kernel

Date	Tue, 26 Feb 2013 15:24:28 +0900

This patch adds support for extracting LZ4-compressed kernel images,
as well as LZ4-compressed ramdisk images in the kernel boot process.

This depends on the patch below
decompressor: Add LZ4 decompressor module

Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>

v2:
- Clean up code
- Use lz4_decompress() for LZ4-compressed kernel during boot-process

Signed-off-by: Paul Reioux <reioux@gmail.com>
arm: Add support for LZ4-compressed kernel

Date	Tue, 26 Feb 2013 15:24:29 +0900

This patch integrates the LZ4 decompression code to the arm pre-boot code.
And it depends on two patchs below

lib: Add support for LZ4-compressed kernel
decompressor: Add LZ4 decompressor module

Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>

v2:
- Apply CFLAGS, -Os to decompress.o to improve decompress
  performance during boot-up process

Signed-off-by: Paul Reioux <reioux@gmail.com>
lib: Add lz4 compressor module

From	Chanho Min <>

This patch adds support for LZ4 compression in the Linux Kernel.
LZ4 Compression APIs for kernel are based on LZ4 implementation
by Yann Collet and changed with kernel coding style.

LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
LZ4 source repository : http://code.google.com/p/lz4/
svn revision : r90

Two APIs are added:
lz4_compress() support basic lz4 compression whereas lz4hc_compress() support
high compression or CPU performance get lower but compression ratio get higher.
Also, we require the pre-allocated working memory with the defined size and
destination buffer must be allocated with the size of lz4_compressbound.

Signed-off-by: Chanho Min <chanho.min@lge.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>
crypto: Add lz4 Cryptographic API

From	Chanho Min <>

This patch adds support for lz4 and lz4hc compression algorithm
using the lib/lz4/* codebase.
Signed-off-by: Chanho Min <chanho.min@lge.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>
lib/lz4/lz4_compress: fix macro usage error

Signed-off-by: Paul Reioux <reioux@gmail.com>
LZ4: compression/decompression signedness mismatch (v2)

LZ4 compression and decompression functions require different
in signedness input/output parameters: unsigned char for
compression and signed char for decompression.

Change decompression API to require "(const) unsigned char *".

v2: minor coding style fix.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>