memory hotplug: reset pgdat->kswapd to NULL if creating kernel thread fails

If kthread_run() fails, pgdat->kswapd contains errno.  When we stop this
thread, we only check whether pgdat->kswapd is NULL and access it.  If it
contains errno, it will cause page fault.  Reset pgdat->kswapd to NULL
when creating kernel thread fails can avoid this problem.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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

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

Conflicts:
arch/cris/include/asm/Kbuild
arch/h8300/include/asm/Kbuild
arch/m32r/include/asm/Kbuild
arch/x86/kernel/signal.c

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

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

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

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

Merge remote-tracking branch 'renesas/next'

Merge remote-tracking branch 'ep93xx/ep93xx-for-next'

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

Conflicts:
arch/arm/mach-ux500/cpu-db8500.c
drivers/mtd/nand/Kconfig
drivers/usb/host/Kconfig

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

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

Conflicts:
drivers/net/tun.c

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

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

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

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

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

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 'drivers-x86/linux-next'

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

Conflicts:
drivers/hid/hid-picolcd.c

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

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

Conflicts:
arch/powerpc/include/asm/kvm_ppc.h
arch/powerpc/kvm/e500_tlb.c
include/linux/kvm.h

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

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

Merge remote-tracking branch 'kmemleak/kmemleak'

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

Conflicts:
arch/Kconfig
arch/x86/Kconfig
kernel/rcutree.h
kernel/rcutree_plugin.h
kernel/sched/core.c

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

Conflicts:
arch/Kconfig

Merge commit 'refs/next/20120905/spi-mb'

Conflicts:
drivers/mmc/host/mxs-mmc.c

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

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

Conflicts:
Documentation/edac.txt
drivers/edac/amd64_edac.c

Merge remote-tracking branch 'edac/linux_next'

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

Conflicts:
kernel/audit_tree.c

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

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

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

Conflicts:
drivers/scsi/ipr.c

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

Merge remote-tracking branch 'iommu/next'

Merge remote-tracking branch 'selinux/master'

Merge remote-tracking branch 'security/next'

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

Merge remote-tracking branch 'omap_dss2/for-next'

Conflicts:
drivers/video/omap2/dss/sdi.c

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

Merge remote-tracking branch 'battery/master'

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

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

Merge commit 'refs/next/20120905/slab'

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

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

Merge branch 'quilt/device-mapper'

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

Merge remote-tracking branch 'input/next'

Merge branch 'quilt/rr'

Conflicts:
arch/alpha/Kconfig
arch/mips/kernel/module.c
arch/s390/Kconfig
arch/xtensa/Kconfig

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

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

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

Merge remote-tracking branch 'crypto/master'

Conflicts:
crypto/Kconfig

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

Merge remote-tracking branch 'mtd/master'

Merge remote-tracking branch 'bluetooth/master'

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

Conflicts:
net/socket.c

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

Merge remote-tracking branch 'isci/all'

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

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

Merge remote-tracking branch 'dlm/next'

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

Merge remote-tracking branch 'thermal/next'

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

Conflicts:
drivers/cpuidle/coupled.c
include/linux/cpuidle.h

Merge remote-tracking branch 'pstore/master'

Merge remote-tracking branch 'libata/NEXT'

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

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

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

Conflicts:
arch/arm/mach-imx/mach-imx27_visstrim_m10.c

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

Merge branch 'quilt/jdelvare-hwmon'

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

Merge branch 'quilt/i2c'

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

Merge remote-tracking branch 'pci/next'

Conflicts:
drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
drivers/rapidio/devices/tsi721.c

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

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

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

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

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 'gfs2/master'

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

Merge remote-tracking branch 'ext4/dev'

Merge remote-tracking branch 'ext3/for_next'

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

Merge remote-tracking branch 'xtensa/for_next'

Merge remote-tracking branch 'unicore32/unicore32'

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

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

Merge remote-tracking branch 's390/features'