mm: frontswap: add frontswap header file

Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory.  For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.

Frontswap and cleancache (which was merged at 3.0) are the only
necessary changes to the core kernel for transcendent memory; all
other supporting code is implemented as drivers.  See "Transcendent
memory in a nutshell" for a current (Aug 2011) and detailed overview of
frontswap and related kernel parts: https://lwn.net/Articles/454795/

Frontswap code was first posted publicly in January 2009 and on LKML
in May 2009, and has remained very stable for over two years now.
It is barely invasive, touching only the swap subsystem and adds only
about 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V10, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change.  As of 3.1, there are
two in-tree users of frontswap patiently waiting for this patchset and for
CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39) and Xen tmem (merged at 3.0 and 3.1).  V5 of the frontswap
patchset has been in linux-next since next-110603 (and this V10
will be there shortly).  Earlier versions of frontswap already appear
in some leading-edge distros.

This first patch of six in this frontswap series provides the header
file for the core code for frontswap that interfaces between the hooks
in the swap subsystem and a frontswap backend via frontswap_ops.
(Note to earlier reviewers:  This patchset has been reorganized due to
feedback from Kame Hiroyuki and Andrew Morton. This patch contains part
of patch 3of4 from the previous series.)

New file added: include/linux/frontswap.h

[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
mm: frontswap: core swap subsystem hooks and headers

(Note to earlier reviewers:  This patchset has been reorganized due to
feedback from Kame Hiroyuki and Andrew Morton. This patch combines patch
1of4 and patch 3of4 from the previous series.)

This second patch of six in the frontswap series contains the changes
to the core swap subsystem.  This includes:

(1) makes available core swap data structures (swap_lock, swap_list and
swap_info) that are needed by frontswap.c but we don't need to expose them
to the dozens of files that include swap.h so we create a new swapfile.h
just to extern-ify these and modify their declarations to non-static

(2) adds frontswap-related elements to swap_info_struct.  Frontswap_map
points to vzalloc'ed one-bit-per-swap-page metadata that indicates
whether the swap page is in frontswap or in the device and frontswap_pages
counts how many pages are in frontswap.

(3) adds hooks in the swap subsystem and extends try_to_unuse so that
frontswap_shrink can do a "partial swapoff".

Note that a failed frontswap_map allocation is safe... failure is noted
by lack of "FS" in the subsequent printk.

[v10: no change]
[v9: akpm@linux-foundation.org: mark some statics __read_mostly]
[v9: akpm@linux-foundation.org: add clarifying comments]
[v9: akpm@linux-foundation.org: no need to loop repeating try_to_unuse]
[v9: error27@gmail.com: remove superfluous check for NULL]
[v8: rebase to 3.0-rc4]
[v8: kamezawa.hiroyu@jp.fujitsu.com: change counter to atomic_t to avoid races]
[v8: kamezawa.hiroyu@jp.fujitsu.com: comment to clarify informational counters]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: add new swap struct elements only if config'd]
[v6: rebase to 3.0-rc1]
[v6: lliubbo@gmail.com: fix null pointer deref if vzalloc fails]
[v6: konrad.wilk@oracl.com: various checks and code clarifications/comments]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com>
Reviewed-by: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
mm: frontswap: core frontswap functionality

(Note to earlier reviewers:  This patchset has been reorganized due to
feedback from Kame Hiroyuki and Andrew Morton. This patch contains part
of patch 3of4 from the previous series.)

This third patch of six in the frontswap series provides the core
frontswap code that interfaces between the hooks in the swap subsystem
and a frontswap backend via frontswap_ops.

[v10: sjenning@linux.vnet.ibm.com: fix debugfs calls on 32-bit]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v9: akpm@linux-foundation.org: mark some statics __read_mostly]
[v9: akpm@linux-foundation.org: add clarifying comments]
[v9: akpm@linux-foundation.org: no need to loop repeating try_to_unuse]
[v9: error27@gmail.com: remove superfluous check for NULL]
[v8: rebase to 3.0-rc4]
[v8: kamezawa.hiroyu@jp.fujitsu.com: add comment to clarify find_next_to_unuse]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: use new static inlines, no-ops if not config'd]
[v6: rebase to 3.1-rc1]
[v6: lliubbo@gmail.com: use vzalloc]
[v6: lliubbo@gmail.com: fix null pointer deref if vzalloc fails]
[v6: konrad.wilk@oracl.com: various checks and code clarifications/comments]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
mm: frontswap: config and doc files

This fourth patch of six in the frontswap series adds configuration
and documentation files.

[v10: no change]
[v9: akpm@linux-foundation.org: sysfs->debugfs; no longer need Doc/ABI file]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v6: rebase to 3.0-rc1]
[v5: change config default to n]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
staging: zsmalloc: zsmalloc memory allocation library

This patch creates a new memory allocation library named
zsmalloc.

NOTE: zsmalloc currently depends on SPARSEMEM for the MAX_PHYSMEM_BITS
value needed to determine the format of the object handle. There may
be a better way to do this.  Feedback is welcome.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zcache-main: frontswap v10 compatibility fixup

Signed-off-by: Paul Reioux <reioux@gmail.com>
mm: cleancache: update to match akpm frontswap feedback

This is the fifth patch of six in the frontswap series; changes made to
frontswap due to feedback from akpm/others must also be made to cleancache
for consistency.  These are: (1) change sysfs to debugfs; (2) change
use of the term "flush" to "invalidate".  Note that some changes
for (2) are deferred to the next patch in this patchset in order to
coordinate with simultaneous required driver changes.

[v10: no change]
[v9: akpm@linux-foundation.org: sysfs->debugfs; no longer need Doc/ABI file]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 2]

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
modified for Linux 3.1.x kernel from LKML

Signed-off-by: Paul Reioux <reioux@gmail.com>
mm: frontswap/cleancache: final flush->invalidate

This sixth patch of six in this frontswap series completes the renaming
from "flush" to "invalidate" across both tmem frontends (cleancache and
frontswap) and both tmem backends (Xen and zcache), as required by akpm.
This change is completely cosmetic.

[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 3]

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
modified for Linux 3.1.x from LKML reference

Signed-off-by: Paul Reioux <reioux@gmail.com>
staging: zcache: crypto API support

This patch allow zcache to use the crypto API for page compression.
It replaces the direct LZO compress/decompress calls with calls
into the crypto compression API. The compressor to be used is
specified in the kernel boot line with the zcache parameter like:
zcache=lzo or zcache=deflate.  If the specified compressor can't
be loaded, zcache uses lzo as the default compressor.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: zcache: replace xvmalloc with zsmalloc

Replaces xvmalloc with zsmalloc as the persistent memory allocator
for zcache

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: zram: remove xvmalloc

Removes the xvmalloc allocator code from the zram driver

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: zram: replace xvmalloc with zsmalloc

Replaces xvmalloc with zsmalloc as the compressed page allocator
for zram

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: fix powerpc linux-next break on zsmalloc

linux/vmalloc.h added to zsmalloc-main.c to resolve implicit
declaration errors.

X86 dependency added to zsmalloc and dependent drivers zcache and zram.

This X86 only requirement is not ideal.  Working to find portable
functions for __flush_tlb_one and set_pte.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zram: sync with kernel.org @ 5fa5a90116be97cd15deac3f45b602c2e5c5fb58

Signed-off-by: Paul Reioux <reioux@gmail.com>
staging: zcache: make zcache builtin only

zcache cannot currently be loaded as a module.  However
the Kconfig allows it to be built as a module; something that
the user probably does not intend since the module is not
loadable.

This patch switches zcache from a tristate to a bool in the Kconfig

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: zcache: avoid AB-BA deadlock condition

Commit 9256a47 fixed a deadlock condition, being sure that the buddy
list spinlock is always taken before the page spinlock.

However in zbud_free_and_delist() locking order is the opposite
(page lock -> list lock).

Possible unsafe locking scenario (reported by lockdep):

        CPU0                    CPU1
        ----                    ----
   lock(&(&zbpg->lock)->rlock);
                                lock(zbud_budlists_spinlock);
                                lock(&(&zbpg->lock)->rlock);
   lock(zbud_budlists_spinlock);

Fix by grabbing the locks in opposite order in zbud_free_and_delist().

Signed-off-by: Andrea Righi <andrea@betterlinux.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: zcache: fix length type mismatch

This fixes a type mismatch in the compression code where
a size_t pointer was cast to a unsigned int pointer.  On
little endian archs, there is no issue.  However on big
endian archs, the value is incorrect, taking the high
order bits and truncating the lower order bits.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: zcache: fix memory corruption bug

This patch fixes a bug where the zv code writes before the allocated
buffer, resulting in system memory corruption. This was introduced
during the switch from xvmalloc to zsmalloc.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging/zmem: Use lockdep_assert_held instead of spin_is_locked

WARN_ON(!spin_is_locked()) will always trigger on UP.
Use lockdep_assert_held instead.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zcache-main: sync with kernel.org @ c234434835b1f4bad9bdbae6710044cba387c9e5 Signed-off-by: Paul Reioux <reioux@gmail.com>