linux.git/kernel/cpuset.c, branch v4.0-rc2

cpuset: use %*pb[l] to print bitmaps including cpumasks and nodemasks

2015-02-14T05:21:37+00:00

printk and friends can now format bitmaps using '%*pb[l]'.  cpumask
and nodemask also provide cpumask_pr_args() and nodemask_pr_args()
respectively which can be used to generate the two printf arguments
necessary to format the specified cpu/nodemask.

* kernel/cpuset.c::cpuset_print_task_mems_allowed() used a static
  buffer which is protected by a dedicated spinlock.  Removed.

Signed-off-by: Tejun Heo 
Cc: Li Zefan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/cpuset.c: Mark cpuset_init_current_mems_allowed as __init

2015-02-13T02:54:11+00:00

The only caller of cpuset_init_current_mems_allowed is the __init
annotated build_all_zonelists_init, so we can also make the former __init.

Signed-off-by: Rasmus Villemoes 
Cc: Vlastimil Babka 
Cc: Rik van Riel 
Cc: Joonsoo Kim 
Cc: David Rientjes 
Cc: Vishnu Pratap Singh 
Cc: Pintu Kumar 
Cc: Michal Nazarewicz 
Cc: Mel Gorman 
Cc: Paul Gortmaker 
Cc: Peter Zijlstra 
Cc: Tim Chen 
Cc: Hugh Dickins 
Cc: Li Zefan 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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.

cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags

2014-09-25T02:16:06+00:00

When we change cpuset.memory_spread_{page,slab}, cpuset will flip
PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset.
This should be done using atomic bitops, but currently we don't,
which is broken.

Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happened
when one thread tried to clear PF_USED_MATH while at the same time another
thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on
the same task.

Here's the full report:
https://lkml.org/lkml/2014/9/19/230

To fix this, we make PF_SPREAD_PAGE and PF_SPREAD_SLAB atomic flags.

v4:
- updated mm/slab.c. (Fengguang Wu)
- updated Documentation.

Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Miao Xie 
Cc: Kees Cook 
Fixes: 950592f7b991 ("cpusets: update tasks' page/slab spread flags in time")
Cc:  # 2.6.31+
Reported-by: Tetsuo Handa 
Signed-off-by: Zefan Li 
Signed-off-by: Tejun Heo