From: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Date: Mon, 16 Jul 2007 06:39:47 +0000 (-0700)
Subject: Fix stop_machine_run problem with naughty real time process
X-Git-Tag: v2.6.23-rc1~949
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=85653af7d488702165eba72c6c1dd0250fae4e70;p=pandora-kernel.git

Fix stop_machine_run problem with naughty real time process

stop_machine_run() does its work on "kstopmachine" thread having max
priority.  However that thread get such priority after woken up.
Therefore, in the following case ...

  - "kstopmachine" try to run on CPU1

  - There is a real time process which doesn't relinquish CPU time
    voluntary on CPU1

...  "kstopmachine" can't start to run and the CPU on which
    stop_machine_run() is runing hangs up.  To fix this problem, call
    sched_setscheduler() before waking up that thread.

Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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