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  1. 08 1月, 2013 10 次提交
    • T
      cpuset: drop async_rebuild_sched_domains() · 699140ba
      由 Tejun Heo 提交于 
      In general, we want to make cgroup_mutex one of the outermost locks
and be able to use get_online_cpus() and friends from cgroup methods.
With cpuset hotplug made async, get_online_cpus() can now be nested
inside cgroup_mutex.

Currently, cpuset avoids nesting get_online_cpus() inside cgroup_mutex
by bouncing sched_domain rebuilding to a work item.  As such nesting
is allowed now, remove the workqueue bouncing code and always rebuild
sched_domains synchronously.  This also nests sched_domains_mutex
inside cgroup_mutex, which is intended and should be okay.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      699140ba
    • T
      cpuset: don't nest cgroup_mutex inside get_online_cpus() · 3a5a6d0c
      由 Tejun Heo 提交于 
      CPU / memory hotplug path currently grabs cgroup_mutex from hotplug
event notifications.  We want to separate cpuset locking from cgroup
core and make cgroup_mutex outer to hotplug synchronization so that,
among other things, mechanisms which depend on get_online_cpus() can
be used from cgroup callbacks.  In general, we want to keep
cgroup_mutex the outermost lock to minimize locking interactions among
different controllers.

Convert cpuset_handle_hotplug() to cpuset_hotplug_workfn() and
schedule it from the hotplug notifications.  As the function can
already handle multiple mixed events without any input, converting it
to a work function is mostly trivial; however, one complication is
that cpuset_update_active_cpus() needs to update sched domains
synchronously to reflect an offlined cpu to avoid confusing the
scheduler.  This is worked around by falling back to the the default
single sched domain synchronously before scheduling the actual hotplug
work.  This makes sched domain rebuilt twice per CPU hotplug event but
the operation isn't that heavy and a lot of the second operation would
be noop for systems w/ single sched domain, which is the common case.

This decouples cpuset hotplug handling from the notification callbacks
and there can be an arbitrary delay between the actual event and
updates to cpusets.  Scheduler and mm can handle it fine but moving
tasks out of an empty cpuset may race against writes to the cpuset
restoring execution resources which can lead to confusing behavior.
Flush hotplug work item from cpuset_write_resmask() to avoid such
confusions.

v2: Synchronous sched domain rebuilding using the fallback sched
    domain added.  This fixes various issues caused by confused
    scheduler putting tasks on a dead CPU, including the one reported
    by Li Zefan.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      3a5a6d0c
    • T
      cpuset: reorganize CPU / memory hotplug handling · deb7aa30
      由 Tejun Heo 提交于 
      Reorganize hotplug path to prepare for async hotplug handling.

* Both CPU and memory hotplug handlings are collected into a single
  function - cpuset_handle_hotplug().  It doesn't take any argument
  but compares the current setttings of top_cpuset against what's
  actually available to determine what happened.  This function
  directly updates top_cpuset.  If there are CPUs or memory nodes
  which are taken down, cpuset_propagate_hotplug() in invoked on all
  !root cpusets.

* cpuset_propagate_hotplug() is responsible for updating the specified
  cpuset so that it doesn't include any resource which isn't available
  to top_cpuset.  If no CPU or memory is left after update, all tasks
  are moved to the nearest ancestor with both resources.

* update_tasks_cpumask() and update_tasks_nodemask() are now always
  called after cpus or mems masks are updated even if the cpuset
  doesn't have any task.  This is for brevity and not expected to have
  any measureable effect.

* cpu_active_mask and N_HIGH_MEMORY are read exactly once per
  cpuset_handle_hotplug() invocation, all cpusets share the same view
  of what resources are available, and cpuset_handle_hotplug() can
  handle multiple resources going up and down.  These properties will
  allow async operation.

The reorganization, while drastic, is equivalent and shouldn't cause
any behavior difference.  This will enable making hotplug handling
async and remove get_online_cpus() -> cgroup_mutex nesting.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      deb7aa30
    • T
      cpuset: cleanup cpuset[_can]_attach() · 4e4c9a14
      由 Tejun Heo 提交于 
      cpuset_can_attach() prepare global variables cpus_attach and
cpuset_attach_nodemask_{to|from} which are used by cpuset_attach().
There is no reason to prepare in cpuset_can_attach().  The same
information can be accessed from cpuset_attach().

Move the prepartion logic from cpuset_can_attach() to cpuset_attach()
and make the global variables static ones inside cpuset_attach().

With this change, there's no reason to keep
cpuset_attach_nodemask_{from|to} global.  Move them inside
cpuset_attach().  Unfortunately, we need to keep cpus_attach global as
it can't be allocated from cpuset_attach().

v2: cpus_attach not converted to cpumask_t as per Li Zefan and Rusty
    Russell.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
      4e4c9a14
    • T
      cpuset: introduce cpuset_for_each_child() · ae8086ce
      由 Tejun Heo 提交于 
      Instead of iterating cgroup->children directly, introduce and use
cpuset_for_each_child() which wraps cgroup_for_each_child() and
performs online check.  As it uses the generic iterator, it requires
RCU read locking too.

As cpuset is currently protected by cgroup_mutex, non-online cpusets
aren't visible to all the iterations and this patch currently doesn't
make any functional difference.  This will be used to de-couple cpuset
locking from cgroup core.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      ae8086ce
    • T
      cpuset: introduce CS_ONLINE · efeb77b2
      由 Tejun Heo 提交于 
      Add CS_ONLINE which is set from css_online() and cleared from
css_offline().  This will enable using generic cgroup iterator while
allowing decoupling cpuset from cgroup internal locking.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      efeb77b2
    • T
      cpuset: introduce ->css_on/offline() · c8f699bb
      由 Tejun Heo 提交于 
      Add cpuset_css_on/offline() and rearrange css init/exit such that,

* Allocation and clearing to the default values happen in css_alloc().
  Allocation now uses kzalloc().

* Config inheritance and registration happen in css_online().

* css_offline() undoes what css_online() did.

* css_free() frees.

This doesn't introduce any visible behavior changes.  This will help
cleaning up locking.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      c8f699bb
    • T
      cpuset: remove fast exit path from remove_tasks_in_empty_cpuset() · 0772324a
      由 Tejun Heo 提交于 
      The function isn't that hot, the overhead of missing the fast exit is
low, the test itself depends heavily on cgroup internals, and it's
gonna be a hindrance when trying to decouple cpuset locking from
cgroup core.  Remove the fast exit path.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      0772324a
    • T
      cpuset: remove unused cpuset_unlock() · 01c889cf
      由 Tejun Heo 提交于 
      Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
      01c889cf
    • T
      cgroup: implement cgroup_rightmost_descendant() · 12a9d2fe
      由 Tejun Heo 提交于 
      Implement cgroup_rightmost_descendant() which returns the right most
descendant of the specified cgroup.  This can be used to skip the
cgroup's subtree while iterating with
cgroup_for_each_descendant_pre().
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NLi Zefan <lizefan@huawei.com>
      12a9d2fe
  3. 26 12月, 2012 1 次提交
    • E
      pidns: Stop pid allocation when init dies · c876ad76
      由 Eric W. Biederman 提交于 
      Oleg pointed out that in a pid namespace the sequence.
- pid 1 becomes a zombie
- setns(thepidns), fork,...
- reaping pid 1.
- The injected processes exiting.

Can lead to processes attempting access their child reaper and
instead following a stale pointer.

That waitpid for init can return before all of the processes in
the pid namespace have exited is also unfortunate.

Avoid these problems by disabling the allocation of new pids in a pid
namespace when init dies, instead of when the last process in a pid
namespace is reaped.
Pointed-out-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      c876ad76
  5. 25 12月, 2012 1 次提交
  7. 21 12月, 2012 2 次提交
  9. 20 12月, 2012 7 次提交
  11. 19 12月, 2012 3 次提交
  13. 18 12月, 2012 9 次提交
  15. 17 12月, 2012 1 次提交
  17. 15 12月, 2012 3 次提交
  19. 14 12月, 2012 3 次提交