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Revision 73863ab028579ed98c4f1f36d016536b1b415344 authored by Anton Vorontsov on 31 May 2012, 23:26:23 UTC, committed by Linus Torvalds on 01 June 2012, 00:49:29 UTC 
powerpc: use clear_tasks_mm_cpumask()
 
Current CPU hotplug code has some task->mm handling issues:

1. Working with task->mm w/o getting mm or grabing the task lock is
   dangerous as ->mm might disappear (exit_mm() assigns NULL under
   task_lock(), so tasklist lock is not enough).

   We can't use get_task_mm()/mmput() pair as mmput() might sleep,
   so we must take the task lock while handle its mm.

2. Checking for process->mm is not enough because process' main
   thread may exit or detach its mm via use_mm(), but other threads
   may still have a valid mm.

   To fix this we would need to use find_lock_task_mm(), which would
   walk up all threads and returns an appropriate task (with task
   lock held).

clear_tasks_mm_cpumask() has all the issues fixed, so let's use it.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Makefile 
###
# scripts contains sources for various helper programs used throughout
# the kernel for the build process.
# ---------------------------------------------------------------------------
# kallsyms:      Find all symbols in vmlinux
# pnmttologo:    Convert pnm files to logo files
# conmakehash:   Create chartable
# conmakehash:	 Create arrays for initializing the kernel console tables
# docproc:       Used in Documentation/DocBook

HOST_EXTRACFLAGS += -I$(srctree)/tools/include

hostprogs-$(CONFIG_KALLSYMS)     += kallsyms
hostprogs-$(CONFIG_LOGO)         += pnmtologo
hostprogs-$(CONFIG_VT)           += conmakehash
hostprogs-$(CONFIG_IKCONFIG)     += bin2c
hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable

HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include

always		:= $(hostprogs-y) $(hostprogs-m)

# The following hostprogs-y programs are only build on demand
hostprogs-y += unifdef docproc

# These targets are used internally to avoid "is up to date" messages
PHONY += build_unifdef
build_unifdef: scripts/unifdef FORCE
	@:
build_docproc: scripts/docproc FORCE
	@:

subdir-$(CONFIG_MODVERSIONS) += genksyms
subdir-y                     += mod
subdir-$(CONFIG_SECURITY_SELINUX) += selinux
subdir-$(CONFIG_DTC)         += dtc

# Let clean descend into subdirs
subdir-	+= basic kconfig package selinux
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