mm: methods for teaching filesystems about PG_swapcache pages

In order to teach filesystems to handle swap cache pages, three new page
functions are introduced:

  pgoff_t page_file_index(struct page *);
  loff_t page_file_offset(struct page *);
  struct address_space *page_file_mapping(struct page *);

page_file_index() - gives the offset of this page in the file in
PAGE_CACHE_SIZE blocks.  Like page->index is for mapped pages, this
function also gives the correct index for PG_swapcache pages.

page_file_offset() - uses page_file_index(), so that it will give the
expected result, even for PG_swapcache pages.

page_file_mapping() - gives the mapping backing the actual page; that is
for swap cache pages it will give swap_file->f_mapping.

Change-Id: I13d18bb25be606760eac26cc842eb7c9fc9e4766
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: f981c5950fa85916ba49bea5d9a7a5078f47e569
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[ohaugan@codeaurora.org: Resolved merge issues]
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
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

Change-Id: Ida7dcf6fbd67408e2429483c28c75f59f83310d3
[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>
Git-commit: b430e9d1c6d416306d44dbf3aa3148be7af78abc
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[ohaugan@codeaurora.org: Resolved merge issues]
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
mm: vmscan: Move pages that fail swapout to LRU active list

Move pages that fail swapout to the LRU active list to reduce
pressure on swap device when swapping out is already failing.
This helps when using a pseudo swap device such as zram which
starts failing when memory is low.

Change-Id: Ib136cd0a744378aa93d837a24b9143ee818c80b3
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
mm: swap: Rate limit swap write errors

If an error occurs in the swap subsystem when writing pages
out to a swap device the system might get overflowed with
logging errors because the mm subsystem will continously try
to swap out pages even in the event of error on the swap
device.

Reduce the amount of logging to prevent the kernel log
from being filled with these error messages.

Change-Id: Iddaf6c32ae87132817482cc4cb68b909a1c527e6
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
add extra free kbytes tunable

Add a userspace visible knob to tell the VM to keep an extra amount
of memory free, by increasing the gap between each zone's min and
low watermarks.

This is useful for realtime applications that call system
calls and have a bound on the number of allocations that happen
in any short time period.  In this application, extra_free_kbytes
would be left at an amount equal to or larger than than the
maximum number of allocations that happen in any burst.

It may also be useful to reduce the memory use of virtual
machines (temporarily?), in a way that does not cause memory
fragmentation like ballooning does.

[ccross]
Revived for use on old kernels where no other solution exists.
The tunable will be removed on kernels that do better at avoiding
direct reclaim.

Change-Id: I765a42be8e964bfd3e2886d1ca85a29d60c3bb3e
Signed-off-by: Rik van Riel<riel@redhat.com>
Signed-off-by: Colin Cross <ccross@android.com>
Git-commit: 92189d47f66c67e5fd92eafaa287e153197a454f
Git-repo: https://android.googlesource.com/kernel/common/
[bhargavuln@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Bhargav Upperla <bhargavuln@codeaurora.org>
Sultan_pyramid_defconfig: Enable zRAM and KSM
Sultan_pyramid_defconfig: v1.2.0