hotplug cpu: move tasks in empty cpusets to parent
commit956db3ca0606e78456786ef19fd4dc7a5151a6e1
authorCliff Wickman <cpw@sgi.com>
Thu, 7 Feb 2008 08:14:43 +0000 (7 00:14 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Thu, 7 Feb 2008 16:42:22 +0000 (7 08:42 -0800)
tree0bef3d107df1115ecf76e342f30ecee67a7f3705
parent31a7df01fd0cd786f60873a921aecafac148c290
hotplug cpu: move tasks in empty cpusets to parent

This patch corrects a situation that occurs when one disables all the cpus in
a cpuset.

Currently, the disabled (cpu-less) cpuset inherits the cpus of its parent,
which is incorrect because it may then overlap its cpu-exclusive sibling.

Tasks of an empty cpuset should be moved to the cpuset which is the parent of
their current cpuset.  Or if the parent cpuset has no cpus, to its parent,
etc.

And the empty cpuset should be released (if it is flagged notify_on_release).

Depends on the cgroup_scan_tasks() function (proposed by David Rientjes) to
iterate through all tasks in the cpu-less cpuset.  We are deliberately
avoiding a walk of the tasklist.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/cgroup.h
kernel/cgroup.c
kernel/cpuset.c