Messages in this thread Patch in this message | | | Date | Sun, 9 Jun 2013 17:17:03 +0800 | From | Li Zefan <> | Subject | [PATCH v3 7/7] cpuset: fix to migrate mm correctly in a corner case |
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Before moving tasks out of empty cpusets, update_tasks_nodemask() is called, which calls do_migrate_pages(xx, from, to). Then those tasks are moved to an ancestor, and do_migrate_pages() is called again.
The first time: from = node_to_be_offlined, to = empty. The second time: from = empty, to = ancestor's nodemask.
so looks like no pages will be migrated.
Fix this by:
- Don't call update_tasks_nodemask() on empty cpusets. - Pass cs->old_mems_allowed to do_migrate_pages().
Signed-off-by: Li Zefan <lizefan@huawei.com> --- kernel/cpuset.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index d1d6782..3cd68b8 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1563,9 +1563,16 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) struct cpuset *mems_oldcs = effective_nodemask_cpuset(oldcs); mpol_rebind_mm(mm, &cpuset_attach_nodemask_to); - if (is_memory_migrate(cs)) - cpuset_migrate_mm(mm, &mems_oldcs->mems_allowed, + if (is_memory_migrate(cs)) { + /* + * old_mems_allowed is the same with mems_allowed here, + * except if this task is being moved automatically due + * to hotplug, and in this case mems_allowed is empty + * and old_mems_allowed is the offlined node. + */ + cpuset_migrate_mm(mm, &mems_oldcs->old_mems_allowed, &cpuset_attach_nodemask_to); + } mmput(mm); } @@ -2155,7 +2162,7 @@ retry: * for empty cpuset to take on ancestor's cpumask. */ if ((sane && cpumask_empty(cs->cpus_allowed)) || - !cpumask_empty(&off_cpus)) + (!cpumask_empty(&off_cpus) && !cpumask_empty(cs->cpus_allowed))) update_tasks_cpumask(cs, NULL); mutex_lock(&callback_mutex); @@ -2167,7 +2174,7 @@ retry: * for empty cpuset to take on ancestor's nodemask. */ if ((sane && nodes_empty(cs->mems_allowed)) || - !nodes_empty(off_mems)) + (!nodes_empty(off_mems) && !nodes_empty(cs->mems_allowed))) update_tasks_nodemask(cs, NULL); is_empty = cpumask_empty(cs->cpus_allowed) || -- 1.8.0.2
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