linux-stable.git/kernel/cpuset.c, branch v3.19.3

cpuset: Fix cpuset sched_relax_domain_level

2015-03-26T12:59:43+00:00

commit 283cb41f426b723a0255702b761b0fc5d1b53a81 upstream.

The cpuset.sched_relax_domain_level can control how far we do
immediate load balancing on a system. However, it was found on recent
kernels that echo'ing a value into cpuset.sched_relax_domain_level
did not reduce any immediate load balancing.

The reason this occurred was because the update_domain_attr_tree() traversal
did not update for the "top_cpuset". This resulted in nothing being changed
when modifying the sched_relax_domain_level parameter.

This patch is able to address that problem by having update_domain_attr_tree()
allow updates for the root in the cpuset traversal.

Fixes: fc560a26acce ("cpuset: replace cpuset->stack_list with cpuset_for_each_descendant_pre()")
Signed-off-by: Jason Low 
Signed-off-by: Zefan Li 
Signed-off-by: Tejun Heo 
Tested-by: Serge Hallyn 
Signed-off-by: Greg Kroah-Hartman

cpuset: fix a warning when clearing configured masks in old hierarchy

2015-03-26T12:59:42+00:00

commit 79063bffc81f82689bd90e16da1b49408f3bf095 upstream.

When we clear cpuset.cpus, cpuset.effective_cpus won't be cleared:

  # mount -t cgroup -o cpuset xxx /mnt
  # mkdir /mnt/tmp
  # echo 0 > /mnt/tmp/cpuset.cpus
  # echo > /mnt/tmp/cpuset.cpus
  # cat cpuset.cpus

  # cat cpuset.effective_cpus
  0-15

And a kernel warning in update_cpumasks_hier() is triggered:

 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 4028 at kernel/cpuset.c:894 update_cpumasks_hier+0x471/0x650()

Signed-off-by: Zefan Li 
Signed-off-by: Tejun Heo 
Tested-by: Serge Hallyn 
Signed-off-by: Greg Kroah-Hartman

cpuset: initialize effective masks when clone_children is enabled

2015-03-26T12:59:42+00:00

commit 790317e1b266c776765a4bdcedefea706ff0fada upstream.

If clone_children is enabled, effective masks won't be initialized
due to the bug:

  # mount -t cgroup -o cpuset xxx /mnt
  # echo 1 > cgroup.clone_children
  # mkdir /mnt/tmp
  # cat /mnt/tmp/
  # cat cpuset.effective_cpus

  # cat cpuset.cpus
  0-15

And then this cpuset won't constrain the tasks in it.

Either the bug or the fix has no effect on unified hierarchy, as
there's no clone_chidren flag there any more.

Reported-by: Christian Brauner 
Reported-by: Serge Hallyn 
Signed-off-by: Zefan Li 
Signed-off-by: Tejun Heo 
Tested-by: Serge Hallyn 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2014-12-12T02:57:19+00:00

Pull cgroup update from Tejun Heo:
 "cpuset got simplified a bit.  cgroup core got a fix on unified
  hierarchy and grew some effective css related interfaces which will be
  used for blkio support for writeback IO traffic which is currently
  being worked on"

* 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: implement cgroup_get_e_css()
  cgroup: add cgroup_subsys->css_e_css_changed()
  cgroup: add cgroup_subsys->css_released()
  cgroup: fix the async css offline wait logic in cgroup_subtree_control_write()
  cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write()
  cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask()
  cpuset: lock vs unlock typo
  cpuset: simplify cpuset_node_allowed API
  cpuset: convert callback_mutex to a spinlock

sched/deadline: Ensure that updates to exclusive cpusets don't break AC

2014-10-28T09:48:00+00:00

How we deal with updates to exclusive cpusets is currently broken.
As an example, suppose we have an exclusive cpuset composed of
two cpus: A[cpu0,cpu1]. We can assign SCHED_DEADLINE task to it
up to the allowed bandwidth. If we want now to modify cpusetA's
cpumask, we have to check that removing a cpu's amount of
bandwidth doesn't break AC guarantees. This thing isn't checked
in the current code.

This patch fixes the problem above, denying an update if the
new cpumask won't have enough bandwidth for SCHED_DEADLINE tasks
that are currently active.

Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Li Zefan 
Cc: cgroups@vger.kernel.org
Link: http://lkml.kernel.org/r/5433E6AF.5080105@arm.com
Signed-off-by: Ingo Molnar

sched/deadline: Fix bandwidth check/update when migrating tasks between exclusive cpusets

2014-10-28T09:47:58+00:00

Exclusive cpusets are the only way users can restrict SCHED_DEADLINE tasks
affinity (performing what is commonly called clustered scheduling).
Unfortunately, such thing is currently broken for two reasons:

 - No check is performed when the user tries to attach a task to
   an exlusive cpuset (recall that exclusive cpusets have an
   associated maximum allowed bandwidth).

 - Bandwidths of source and destination cpusets are not correctly
   updated after a task is migrated between them.

This patch fixes both things at once, as they are opposite faces
of the same coin.

The check is performed in cpuset_can_attach(), as there aren't any
points of failure after that function. The updated is split in two
halves. We first reserve bandwidth in the destination cpuset, after
we pass the check in cpuset_can_attach(). And we then release
bandwidth from the source cpuset when the task's affinity is
actually changed. Even if there can be time windows when sched_setattr()
may erroneously fail in the source cpuset, we are fine with it, as
we can't perfom an atomic update of both cpusets at once.

Reported-by: Daniel Wagner 
Reported-by: Vincent Legout 
Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Dario Faggioli 
Cc: Michael Trimarchi 
Cc: Fabio Checconi 
Cc: michael@amarulasolutions.com
Cc: luca.abeni@unitn.it
Cc: Li Zefan 
Cc: Linus Torvalds 
Cc: cgroups@vger.kernel.org
Link: http://lkml.kernel.org/r/1411118561-26323-3-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar

cpuset: lock vs unlock typo

2014-10-27T15:53:29+00:00

This will deadlock instead of unlocking.

Fixes: f73eae8d8384 ('cpuset: simplify cpuset_node_allowed API')
Signed-off-by: Dan Carpenter 
Acked-by: Vladimir Davydov 
Signed-off-by: Tejun Heo

cpuset: simplify cpuset_node_allowed API

2014-10-27T15:15:27+00:00

Current cpuset API for checking if a zone/node is allowed to allocate
from looks rather awkward. We have hardwall and softwall versions of
cpuset_node_allowed with the softwall version doing literally the same
as the hardwall version if __GFP_HARDWALL is passed to it in gfp flags.
If it isn't, the softwall version may check the given node against the
enclosing hardwall cpuset, which it needs to take the callback lock to
do.

Such a distinction was introduced by commit 02a0e53d8227 ("cpuset:
rework cpuset_zone_allowed api"). Before, we had the only version with
the __GFP_HARDWALL flag determining its behavior. The purpose of the
commit was to avoid sleep-in-atomic bugs when someone would mistakenly
call the function without the __GFP_HARDWALL flag for an atomic
allocation. The suffixes introduced were intended to make the callers
think before using the function.

However, since the callback lock was converted from mutex to spinlock by
the previous patch, the softwall check function cannot sleep, and these
precautions are no longer necessary.

So let's simplify the API back to the single check.

Suggested-by: David Rientjes 
Signed-off-by: Vladimir Davydov 
Acked-by: Christoph Lameter 
Acked-by: Zefan Li 
Signed-off-by: Tejun Heo

cpuset: convert callback_mutex to a spinlock

2014-10-27T15:15:26+00:00

The callback_mutex is only used to synchronize reads/updates of cpusets'
flags and cpu/node masks. These operations should always proceed fast so
there's no reason why we can't use a spinlock instead of the mutex.

Converting the callback_mutex into a spinlock will let us call
cpuset_zone_allowed_softwall from atomic context. This, in turn, makes
it possible to simplify the code by merging the hardwall and asoftwall
checks into the same function, which is the business of the next patch.

Suggested-by: Zefan Li 
Signed-off-by: Vladimir Davydov 
Acked-by: Christoph Lameter 
Acked-by: Zefan Li 
Signed-off-by: Tejun Heo

Merge branch 'for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2014-10-10T11:24:40+00:00

Pull cgroup updates from Tejun Heo:
 "Nothing too interesting.  Just a handful of cleanup patches"

* 'for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  Revert "cgroup: remove redundant variable in cgroup_mount()"
  cgroup: remove redundant variable in cgroup_mount()
  cgroup: fix missing unlock in cgroup_release_agent()
  cgroup: remove CGRP_RELEASABLE flag
  perf/cgroup: Remove perf_put_cgroup()
  cgroup: remove redundant check in cgroup_ino()
  cpuset: simplify proc_cpuset_show()
  cgroup: simplify proc_cgroup_show()
  cgroup: use a per-cgroup work for release agent
  cgroup: remove bogus comments
  cgroup: remove redundant code in cgroup_rmdir()
  cgroup: remove some useless forward declarations
  cgroup: fix a typo in comment.