linux-toradex.git/kernel/cpuset.c, branch v2.6.30-rc5

cpusets: prevent PF_THREAD_BOUND tasks from attaching to non-root cpusets

2009-04-03T02:04:57+00:00

Kthreads that have the PF_THREAD_BOUND bit set in their flags are bound to a
specific cpu.  Thus, their set of allowed cpus shall not change.

This patch prevents such threads from attaching to non-root cpusets.  They do
not have mempolicies that restrict them to a subset of system nodes and, since
their cpumask may never change, they cannot use any of the features of
cpusets.

The tasks will forever be a member of the root cpuset and will be returned
when listing the tasks attached to that cpuset.

Cc: Paul Menage 
Cc: Peter Zijlstra 
Cc: Dhaval Giani 
Signed-off-by: David Rientjes 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpusets: allow cpusets to be configured/built on non-SMP systems

2009-04-03T02:04:57+00:00

Allow cpusets to be configured/built on non-SMP systems

Currently it's impossible to build cpusets under UML on x86-64, since
cpusets depends on SMP and x86-64 UML doesn't support SMP.

There's code in cpusets that doesn't depend on SMP.  This patch surrounds
the minimum amount of cpusets code with #ifdef CONFIG_SMP in order to
allow cpusets to build/run on UP systems (for testing purposes under UML).

Reviewed-by: Li Zefan 
Signed-off-by: Paul Menage 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpusets: replace zone allowed functions with node allowed

2009-04-03T02:04:57+00:00

The cpuset_zone_allowed() variants are actually only a function of the
zone's node.

Cc: Paul Menage 
Acked-by: Christoph Lameter 
Cc: Randy Dunlap 
Signed-off-by: David Rientjes 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset: remove struct cpuset_hotplug_scanner

2009-04-03T02:04:57+00:00

Use cgroup_scanner.data, instead of introducing cpuset_hotplug_scanner.

Signed-off-by: Li Zefan 
Cc: KAMEZAWA Hiroyuki 
Cc: Paul Menage 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset: avoid changing cpuset's mems when errno returned

2009-04-03T02:04:57+00:00

When writing to cpuset.mems, cpuset has to update its mems_allowed before
calling update_tasks_nodemask(), but this function might return -ENOMEM.

To avoid this rare case, we allocate the memory before changing
mems_allowed, and then pass to update_tasks_nodemask().  Similar to what
update_cpumask() does.

Signed-off-by: Li Zefan 
Cc: KAMEZAWA Hiroyuki 
Cc: Paul Menage 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset: rewrite update_tasks_nodemask()

2009-04-03T02:04:57+00:00

This patch uses cgroup_scan_tasks() to rebind tasks' vmas to new cpuset's
mems_allowed.

Not only simplify the code largely, but also avoid allocating an array to
hold mm pointers of all the tasks in the cpuset.  This array can be big
(size > PAGESIZE) if we have lots of tasks in that cpuset, thus has a
chance to fail the allocation when under memory stress.

Signed-off-by: Li Zefan 
Cc: KAMEZAWA Hiroyuki 
Cc: Paul Menage 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset: fix possible races in cpu/memory hotplug

2009-04-03T02:04:56+00:00

Change to cpuset->cpus_allowed and cpuset->mems_allowed should be protected
by callback_mutex, otherwise the reader may read wrong cpus/mems. This is
cpuset's lock rule.

Signed-off-by: Li Zefan 
Cc: Paul Menage 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: show correct file mode

2009-04-03T02:04:54+00:00

We have some read-only files and write-only files, but currently they are
all set to 0644, which is counter-intuitive and cause trouble for some
cgroup tools like libcgroup.

This patch adds 'mode' to struct cftype to allow cgroup subsys to set it's
own files' file mode, and for the most cases cft->mode can be default to 0
and cgroup will figure out proper mode.

Acked-by: Paul Menage 
Reviewed-by: KAMEZAWA Hiroyuki 
Signed-off-by: Li Zefan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset: fix possible deadlock in async_rebuild_sched_domains

2009-01-19T01:44:00+00:00

Lockdep reported some possible circular locking info when we tested cpuset on
NUMA/fake NUMA box.

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.29-rc1-00224-ga652504 #111
-------------------------------------------------------
bash/2968 is trying to acquire lock:
 (events){--..}, at: [] flush_work+0x24/0xd8

but task is already holding lock:
 (cgroup_mutex){--..}, at: [] cgroup_lock_live_group+0x12/0x29

which lock already depends on the new lock.
......
-------------------------------------------------------

Steps to reproduce:
# mkdir /dev/cpuset
# mount -t cpuset xxx /dev/cpuset
# mkdir /dev/cpuset/0
# echo 0 > /dev/cpuset/0/cpus
# echo 0 > /dev/cpuset/0/mems
# echo 1 > /dev/cpuset/0/memory_migrate
# cat /dev/zero > /dev/null &
# echo $! > /dev/cpuset/0/tasks

This is because async_rebuild_sched_domains has the following lock sequence:
run_workqueue(async_rebuild_sched_domains)
	-> do_rebuild_sched_domains -> cgroup_lock

But, attaching tasks when memory_migrate is set has following:
cgroup_lock_live_group(cgroup_tasks_write)
	-> do_migrate_pages -> flush_work

This patch fixes it by using a separate workqueue thread.

Signed-off-by: Miao Xie 
Signed-off-by: Lai Jiangshan 
Signed-off-by: Ingo Molnar

cgroups: consolidate cgroup documents

2009-01-16T00:39:37+00:00

Move Documentation/cpusets.txt and Documentation/controllers/* to
Documentation/cgroups/

Signed-off-by: Li Zefan 
Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Balbir Singh 
Acked-by: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds