cpu hotplug: fix ksoftirqd termination on cpu hotplug with naughty realtime process
cpu hotplug: fix ksoftirqd termination on cpu hotplug with naughty realtime process

Fix ksoftirqd termination on cpu hotplug with naughty real time process.

Assuming the following case:

 - Try to hot remove CPU2 from CPU1.
 - There is a real time process on CPU2, and that process doesn't sleep at all.
 - That rt process and ksoftirqd/2 is migrated to the CPU0

Then ksoftirqd/2 can't stop becasue that rt process runs everlastingly on
CPU0, and CPU1 waiting the ksoftirqd/2's termination hangs up.  To fix this
problem, set the priority of ksoftirqd/2 to max one before kthread_stop().

[5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org: fix warning]
Signed-off-by: Satoru Takeuchi <10321040b4416ef60f5e5611ae32074e89e435e7@jp.fujitsu.com>
Cc: Rusty Russell <df9728c9e5104131c08c7adb03af425394842596@rustcorp.com.au>
Cc: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@elte.hu>
Cc: Oleg Nesterov <20b70f0af00562e63758b9ee42012ecc96c58590@tv-sign.ru>
Cc: Ashok Raj <82fba5000eac076d0784a0a40de3c3bd46526953@intel.com>
Cc: Gautham R Shenoy <c13571dbffa0eb89c7f8eebdce482897b0f5a685@in.ibm.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas