zsmalloc: move it under mm

This patch moves zsmalloc under mm directory.

Before that, description will explain why we have needed custom allocator.

Zsmalloc is a new slab-based memory allocator for storing compressed
pages.  It is designed for low fragmentation and high allocation success
rate on large object, but <= PAGE_SIZE allocations.

zsmalloc differs from the kernel slab allocator in two primary ways to
achieve these design goals.

zsmalloc never requires high order page allocations to back slabs, or
"size classes" in zsmalloc terms.  Instead it allows multiple single-order
pages to be stitched together into a "zspage" which backs the slab.  This
allows for higher allocation success rate under memory pressure.

Also, zsmalloc allows objects to span page boundaries within the zspage.
This allows for lower fragmentation than could be had with the kernel slab
allocator for objects between PAGE_SIZE/2 and PAGE_SIZE.  With the kernel
slab allocator, if a page compresses to 60% of it original size, the
memory savings gained through compression is lost in fragmentation because
another object of the same size can't be stored in the leftover space.

This ability to span pages results in zsmalloc allocations not being
directly addressable by the user.  The user is given an non-dereferencable
handle in response to an allocation request.  That handle must be mapped,
using zs_map_object(), which returns a pointer to the mapped region that
can be used.  The mapping is necessary since the object data may reside in
two different noncontigious pages.

The zsmalloc fulfills the allocation needs for zram perfectly

[sjenning@linux.vnet.ibm.com: borrow Seth's quote]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Nitin Gupta <ngupta@vflare.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/migrate.c: fix setting of cpupid on page migration twice against normal page

7851a45cd3 ("mm: numa: Copy cpupid on page migration") copies over the
cpupid at page migration time.  it is unnecessary to set it again in
alloc_misplaced_dst_page().

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/migrate.c: fix set cpupid on page migration twice against thp

7851a45cd3 (mm: numa: Copy cpupid on page migration) copies over the
cpupid at page migration time.  It is unnecessary to set it again in
migrate_misplaced_transhuge_page().

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

softirq: use const char * const for softirq_to_name, whitespace neatening

Reduce data size a little.
Reduce checkpatch noise.

$ size kernel/softirq.o*
   text    data     bss     dec     hex filename
  11554    6013    4008   21575    5447 kernel/softirq.o.new
  11474    6093    4008   21575    5447 kernel/softirq.o.old

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

softirq: convert printks to pr_<level>

Use a more current logging style.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

softirq: use ffs() in __do_softirq()

Possible speed improvement of __do_softirq() by using ffs() instead of
using a while loop with an & 1 test then single bit shift.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kernel/kexec.c: use vscnprintf() instead of vsnprintf() in vmcoreinfo_append_str()

vsnprintf() may let 'r' larger than sizeof(buf), in this case, if 'r' is
also less than "vmcoreinfo_max_size - vmcoreinfo_size" (left size of
destination buffer), next memcpy() will read the unexpected addresses.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Merge branch 'akpm-current/current'

Conflicts:
mm/memcontrol.c
mm/mlock.c

Merge remote-tracking branch 'lzo-update/lzo-update'

Merge remote-tracking branch 'random/dev'

Merge remote-tracking branch 'clk/clk-next'

Merge remote-tracking branch 'ktest/for-next'

Merge remote-tracking branch 'userns/for-next'

Merge remote-tracking branch 'pwm/for-next'

Merge remote-tracking branch 'gpio/for-next'

Merge remote-tracking branch 'pinctrl/for-next'

Merge remote-tracking branch 'writeback/writeback-for-next'

Merge remote-tracking branch 'target-updates/for-next'

Conflicts:
drivers/target/target_core_tpg.c

Merge remote-tracking branch 'scsi/for-next'

Merge remote-tracking branch 'char-misc/char-misc-next'

Merge remote-tracking branch 'staging/staging-next'

Conflicts:
drivers/staging/imx-drm/imx-drm-core.c

Merge remote-tracking branch 'usb/usb-next'

Merge remote-tracking branch 'tty/tty-next'

Merge remote-tracking branch 'driver-core/driver-core-next'

Merge remote-tracking branch 'leds/for-next'

Merge remote-tracking branch 'regmap/for-next'

Merge remote-tracking branch 'chrome-platform/for-next'

Merge remote-tracking branch 'xen-tip/linux-next'

Merge remote-tracking branch 'kvm-ppc/kvm-ppc-next'

Merge remote-tracking branch 'kvm-arm/kvm-arm-next'

Merge remote-tracking branch 'kvm/linux-next'

Merge remote-tracking branch 'ftrace/for-next'

Merge remote-tracking branch 'edac-amd/for-next'

Merge remote-tracking branch 'clockevents/clockevents/next'

Conflicts:
drivers/clocksource/clksrc-of.c

Merge remote-tracking branch 'tip/auto-latest'

Conflicts:
drivers/acpi/acpi_extlog.c

next-20131224/spi

Conflicts:
drivers/spi/spi-mpc512x-psc.c

Merge remote-tracking branch 'dt-rh/for-next'

Merge remote-tracking branch 'audit/master'

Merge remote-tracking branch 'trivial/for-next'

Conflicts:
drivers/gpu/drm/qxl/Kconfig

Merge remote-tracking branch 'vfio/next'

Merge remote-tracking branch 'iommu/next'

Merge remote-tracking branch 'watchdog/master'

Merge remote-tracking branch 'selinux/master'

Conflicts:
security/selinux/hooks.c

Merge remote-tracking branch 'security/next'

Revert "regulator: act8865: register all regulators regardless of how many are used"

This reverts commit d04b755273683ed31043563b8a3a2716bd8aa6a9.

Merge remote-tracking branch 'regulator/for-next'

Merge remote-tracking branch 'battery/master'

Merge remote-tracking branch 'mfd-lj/for-mfd-next'

Merge remote-tracking branch 'slab/for-next'

Merge remote-tracking branch 'kgdb/kgdb-next'

Conflicts:
kernel/debug/debug_core.h

Merge remote-tracking branch 'device-mapper/for-next'

Conflicts:
drivers/md/dm-thin.c

Merge remote-tracking branch 'block/for-next'

Conflicts:
fs/f2fs/data.c
fs/f2fs/segment.c
include/trace/events/f2fs.h

Merge remote-tracking branch 'cgroup/for-next'

Merge remote-tracking branch 'input/next'

Merge remote-tracking branch 'virtio/virtio-next'

Merge remote-tracking branch 'modules/modules-next'

Conflicts:
Documentation/module-signing.txt

Merge remote-tracking branch 'sound/for-next'

Conflicts:
sound/soc/fsl/fsl_ssi.c

Merge remote-tracking branch 'drm-tegra/drm/for-next'

Merge remote-tracking branch 'drm-intel/for-linux-next'

Conflicts:
drivers/gpu/drm/i915/intel_ddi.c
drivers/gpu/drm/i915/intel_pm.c

Merge remote-tracking branch 'drm/drm-next'

Conflicts:
drivers/gpu/drm/drm_stub.c
drivers/gpu/drm/i915/intel_pm.c
drivers/staging/imx-drm/imx-drm-core.c

Merge remote-tracking branch 'crypto/master'

Merge remote-tracking branch 'l2-mtd/master'

Merge remote-tracking branch 'infiniband/for-next'

Merge remote-tracking branch 'bluetooth/master'

Merge remote-tracking branch 'wireless-next/master'

Merge remote-tracking branch 'ipsec-next/master'

Revert "macvlan: unify macvlan_pcpu_stats and vlan_pcpu_stats"

This reverts commit cdf3e274cf1b36e9a2fef2d175cabc566af841b2.

Merge remote-tracking branch 'net-next/master'

Conflicts:
drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c
net/ipv6/ip6_tunnel.c
net/ipv6/ip6_vti.c

Merge remote-tracking branch 'slave-dma/next'

Conflicts:
arch/arm/boot/dts/imx51.dtsi
arch/arm/boot/dts/imx53.dtsi

Merge remote-tracking branch 'swiotlb/linux-next'

Merge remote-tracking branch 'dlm/next'

Merge remote-tracking branch 'thermal/next'

Conflicts:
drivers/cpufreq/Kconfig

Merge remote-tracking branch 'idle/next'

Merge remote-tracking branch 'pm/linux-next'

Merge remote-tracking branch 'libata/for-next'

Merge remote-tracking branch 'kbuild/for-next'

Merge remote-tracking branch 'v4l-dvb/master'

Merge remote-tracking branch 'hwmon-staging/hwmon-next'

Merge branch 'jdelvare-hwmon/master'

Merge remote-tracking branch 'i2c/i2c/for-next'

Merge remote-tracking branch 'hid/for-next'

Merge remote-tracking branch 'pci/next'

Merge remote-tracking branch 'xfs/for-next'

Merge remote-tracking branch 'v9fs/for-next'

Merge remote-tracking branch 'nfsd/nfsd-next'

Merge remote-tracking branch 'nfs/linux-next'

Merge remote-tracking branch 'logfs/master'

Merge remote-tracking branch 'jfs/jfs-next'

Merge remote-tracking branch 'gfs2/master'

Merge remote-tracking branch 'fscache/fscache'

Merge remote-tracking branch 'f2fs/dev'

Merge remote-tracking branch 'ext4/dev'

Merge remote-tracking branch 'ext3/for_next'

Merge remote-tracking branch 'ecryptfs/next'

Merge remote-tracking branch 'ceph/master'

Merge remote-tracking branch 'xtensa/for_next'

Merge remote-tracking branch 's390/features'

Merge remote-tracking branch 'mpc5xxx/next'

Conflicts:
arch/powerpc/boot/dts/mpc5125twr.dts

Merge remote-tracking branch 'powerpc/next'

Merge remote-tracking branch 'parisc-hd/for-next'