reboot: rigrate shutdown/reboot to boot cpu

We recently noticed that reboot of a 1024 cpu machine takes approx 16
minutes of just stopping the cpus.  The slowdown was tracked to commit
f96972f.

The current implementation does all the work of hot removing the cpus
before halting the system.  We are switching to just migrating to the
boot cpu and then continuing with shutdown/reboot.

This also has the effect of not breaking x86's command line parameter for
specifying the reboot cpu.  Note, this code was shamelessly copied from
arch/x86/kernel/reboot.c with bits removed pertaining to the reboot_cpu
command line parameter.

Signed-off-by: Robin Holt <holt@sgi.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

cpu-hotplug-provide-a-generic-helper-to-disable-enable-cpu-hotplug-v11

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

CPU hotplug: provide a generic helper to disable/enable CPU hotplug

There are instances in the kernel where we would like to disable CPU
hotplug (from sysfs) during some important operation.  Today the freezer
code depends on this and the code to do it was kinda tailor-made for that.

Restructure the code and make it generic enough to be useful for
other usecases too.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Robin Holt <holt@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

shm-fix-null-pointer-deref-when-userspace-specifies-invalid-hugepage-size-fix

eliminate ugly 80-col tricks

Cc: Dave Jones <davej@redhat.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Li Zefan <lizfan@huawei.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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

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

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

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

Merge remote-tracking branch 'bcon/master'

Conflicts:
drivers/block/Kconfig

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

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

Conflicts:
drivers/staging/nvec/nvec_kbd.c

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

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

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

Conflicts:
drivers/base/cpu.c

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

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

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

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

Conflicts:
arch/s390/include/asm/pgtable.h

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

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

Merge remote-tracking branch 'spi-mb/for-next'

Merge remote-tracking branch 'watchdog/master'

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

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Merge remote-tracking branch 'mfd/master'

Conflicts:
drivers/mfd/intel_msic.c

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

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

Merge branch 'device-mapper/master'

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Merge remote-tracking branch 'input-mt/for-next'

Merge remote-tracking branch 'input/next'

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

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

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

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

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

Merge remote-tracking branch 'crypto/master'

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

Merge remote-tracking branch 'bluetooth/master'

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

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

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

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

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

Merge remote-tracking branch 'thermal/next'

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

Conflicts:
drivers/acpi/processor_driver.c
drivers/base/power/qos.c

Merge remote-tracking branch 'idle/next'

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

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

Merge remote-tracking branch 'pci/next'

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

Conflicts:
fs/xfs/xfs_attr_leaf.c

Merge remote-tracking branch 'ocfs2/linux-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 'fuse/for-next'

Merge remote-tracking branch 'fscache/fscache'

Merge remote-tracking branch 'f2fs/dev'

Merge remote-tracking branch 'ecryptfs/next'

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

Merge remote-tracking branch 'ceph/testing'

Merge remote-tracking branch 'xtensa/for_next'

Merge remote-tracking branch 'sh/sh-latest'

Conflicts:
arch/sh/kernel/cpu/sh2a/Makefile

Merge remote-tracking branch 's390/features'

Merge remote-tracking branch 'mpc5xxx/next'

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

Conflicts:
arch/parisc/include/asm/processor.h
arch/parisc/kernel/irq.c

Merge remote-tracking branch 'mips/mips-for-linux-next'

Merge remote-tracking branch 'microblaze/next'

Merge remote-tracking branch 'm68k/for-next'

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

Merge remote-tracking branch 'arm64/upstream'

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

Conflicts:
arch/arm/mach-highbank/highbank.c
arch/arm/mach-imx/mach-imx6q.c
arch/arm/mach-spear/spear13xx.c
arch/arm/mach-vexpress/v2m.c
arch/arm/mach-zynq/platsmp.c
drivers/clocksource/Makefile
drivers/clocksource/tegra20_timer.c

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

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

Merge remote-tracking branch 'ide/master'

Merge remote-tracking branch 'crypto-current/master'