From: Kirill Tkhai <ktkhai@parallels.com>
Date: Tue, 28 Oct 2014 05:24:34 +0000 (+0300)
Subject: sched: Remove lockdep check in sched_move_task()
X-Git-Tag: omap-for-v3.19/fixes-for-merge-window~94^2~4
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f7b8a47da17c9ee4998f2ca2018fcc424e953c0e;p=pandora-kernel.git

sched: Remove lockdep check in sched_move_task()

sched_move_task() is the only interface to change sched_task_group:
cpu_cgrp_subsys methods and autogroup_move_group() use it.

Everything is synchronized by task_rq_lock(), so cpu_cgroup_attach()
is ordered with other users of sched_move_task(). This means we do no
need RCU here: if we've dereferenced a tg here, the .attach method
hasn't been called for it yet.

Thus, we should pass "true" to task_css_check() to silence lockdep
warnings.

Fixes: eeb61e53ea19 ("sched: Fix race between task_group and sched_task_group")
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414473874.8574.2.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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