From: Tejun Heo <tj@kernel.org>
Date: Fri, 28 Jun 2013 02:37:26 +0000 (-0700)
Subject: cgroup: CGRP_ROOT_SUBSYS_BOUND should be ignored when comparing mount options
X-Git-Tag: omap-for-v3.11/fixes-for-merge-window~44^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ce6cba35777cf96a54ce0d5856dc962566b8717;p=pandora-kernel.git

cgroup: CGRP_ROOT_SUBSYS_BOUND should be ignored when comparing mount options

1672d04070 ("cgroup: fix cgroupfs_root early destruction path")
introduced CGRP_ROOT_SUBSYS_BOUND which is used to mark completion of
subsys binding on a new root; however, this broke remounts.
cgroup_remount() doesn't allow changing root options via remount and
CGRP_ROOT_SUBSYS_BOUND, which is set on all fully initialized roots,
makes the function reject all remounts.

Fix it by putting the options part in the lower 16 bits of root->flags
and masking the comparions.  While at it, make cgroup_remount() emit
an error message explaining why it's rejecting a remount request, so
that it's less of a mystery.

Signed-off-by: Tejun Heo <tj@kernel.org>
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