From: Paul Jackson <pj@sgi.com>
Date: Fri, 31 Mar 2006 10:30:52 +0000 (-0800)
Subject: [PATCH] cpuset: memory migration interaction fix
X-Git-Tag: v2.6.17-rc1~82
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e4e364e865b382f9d99c7fc230ec2ce7df21257a;p=pandora-kernel.git

[PATCH] cpuset: memory migration interaction fix

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>
---

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