Fix memory migration so that it works regardless of what cpuset the invoking
task is in.
If a task invoked a memory migration, by doing one of:
1) writing a different nodemask to a cpuset 'mems' file, or
2) writing a tasks pid to a different cpuset's 'tasks' file,
where the cpuset had its 'memory_migrate' option turned on, then the
allocation of the new pages for the migrated task(s) was constrained
by the invoking tasks cpuset.
If this task wasn't in a cpuset that allowed the requested memory nodes, the
memory migration would happen to some other nodes that were in that invoking
tasks cpuset. This was usually surprising and puzzling behaviour: Why didn't
the pages move? Why did the pages move -there-?
To fix this, temporarilly change the invoking tasks 'mems_allowed' task_struct
field to the nodes the migrating tasks is moving to, so that new pages can be
allocated there.
Signed-off-by: Paul Jackson <pj@sgi.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
e4e364e865