Commit Graph

10 Commits

Author SHA1 Message Date
Tejun Heo 59b6f87344 memcg: make cgroup_event deal with mem_cgroup instead of cgroup_subsys_state
cgroup_event is now memcg specific.  Replace cgroup_event->css with
->memcg and convert [un]register_event() callbacks to take mem_cgroup
pointer instead of cgroup_subsys_state one.  This simplifies the code
slightly and makes css_to_vmpressure() unnecessary which is removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
2013-11-22 18:20:43 -05:00
Tejun Heo 347c4a8747 memcg: remove cgroup_event->cft
The only use of cgroup_event->cft is distinguishing "usage_in_bytes"
and "memsw.usgae_in_bytes" for mem_cgroup_usage_[un]register_event(),
which can be done by adding an explicit argument to the function and
implementing two wrappers so that the two cases can be distinguished
from the function alone.

Remove cgroup_event->cft and the related code including
[un]register_events() methods.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
2013-11-22 18:20:43 -05:00
Linus Torvalds 32dad03d16 Merge branch 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "A lot of activities on the cgroup front.  Most changes aren't visible
  to userland at all at this point and are laying foundation for the
  planned unified hierarchy.

   - The biggest change is decoupling the lifetime management of css
     (cgroup_subsys_state) from that of cgroup's.  Because controllers
     (cpu, memory, block and so on) will need to be dynamically enabled
     and disabled, css which is the association point between a cgroup
     and a controller may come and go dynamically across the lifetime of
     a cgroup.  Till now, css's were created when the associated cgroup
     was created and stayed till the cgroup got destroyed.

     Assumptions around this tight coupling permeated through cgroup
     core and controllers.  These assumptions are gradually removed,
     which consists bulk of patches, and css destruction path is
     completely decoupled from cgroup destruction path.  Note that
     decoupling of creation path is relatively easy on top of these
     changes and the patchset is pending for the next window.

   - cgroup has its own event mechanism cgroup.event_control, which is
     only used by memcg.  It is overly complex trying to achieve high
     flexibility whose benefits seem dubious at best.  Going forward,
     new events will simply generate file modified event and the
     existing mechanism is being made specific to memcg.  This pull
     request contains prepatory patches for such change.

   - Various fixes and cleanups"

Fixed up conflict in kernel/cgroup.c as per Tejun.

* 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (69 commits)
  cgroup: fix cgroup_css() invocation in css_from_id()
  cgroup: make cgroup_write_event_control() use css_from_dir() instead of __d_cgrp()
  cgroup: make cgroup_event hold onto cgroup_subsys_state instead of cgroup
  cgroup: implement CFTYPE_NO_PREFIX
  cgroup: make cgroup_css() take cgroup_subsys * instead and allow NULL subsys
  cgroup: rename cgroup_css_from_dir() to css_from_dir() and update its syntax
  cgroup: fix cgroup_write_event_control()
  cgroup: fix subsystem file accesses on the root cgroup
  cgroup: change cgroup_from_id() to css_from_id()
  cgroup: use css_get() in cgroup_create() to check CSS_ROOT
  cpuset: remove an unncessary forward declaration
  cgroup: RCU protect each cgroup_subsys_state release
  cgroup: move subsys file removal to kill_css()
  cgroup: factor out kill_css()
  cgroup: decouple cgroup_subsys_state destruction from cgroup destruction
  cgroup: replace cgroup->css_kill_cnt with ->nr_css
  cgroup: bounce cgroup_subsys_state ref kill confirmation to a work item
  cgroup: move cgroup->subsys[] assignment to online_css()
  cgroup: reorganize css init / exit paths
  cgroup: add __rcu modifier to cgroup->subsys[]
  ...
2013-09-03 18:25:03 -07:00
Tejun Heo 81eeaf0411 cgroup: make cftype->[un]register_event() deal with cgroup_subsys_state instead of cgroup
cgroup is in the process of converting to css (cgroup_subsys_state)
from cgroup as the principal subsystem interface handle.  This is
mostly to prepare for the unified hierarchy support where css's will
be created and destroyed dynamically but also helps cleaning up
subsystem implementations as css is usually what they are interested
in anyway.

cftype->[un]register_event() is among the remaining couple interfaces
which still use struct cgroup.  Convert it to cgroup_subsys_state.
The conversion is mostly mechanical and removes the last users of
mem_cgroup_from_cont() and cg_to_vmpressure(), which are removed.

v2: indentation update as suggested by Li Zefan.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
2013-08-08 20:11:26 -04:00
Tejun Heo 182446d087 cgroup: pass around cgroup_subsys_state instead of cgroup in file methods
cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup.
Please see the previous commit which converts the subsystem methods
for rationale.

This patch converts all cftype file operations to take @css instead of
@cgroup.  cftypes for the cgroup core files don't have their subsytem
pointer set.  These will automatically use the dummy_css added by the
previous patch and can be converted the same way.

Most subsystem conversions are straight forwards but there are some
interesting ones.

* freezer: update_if_frozen() is also converted to take @css instead
  of @cgroup for consistency.  This will make the code look simpler
  too once iterators are converted to use css.

* memory/vmpressure: mem_cgroup_from_css() needs to be exported to
  vmpressure while mem_cgroup_from_cont() can be made static.
  Updated accordingly.

* cpu: cgroup_tg() doesn't have any user left.  Removed.

* cpuacct: cgroup_ca() doesn't have any user left.  Removed.

* hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left.
  Removed.

* net_cls: cgrp_cls_state() doesn't have any user left.  Removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-08 20:11:24 -04:00
Tejun Heo 8af01f56a0 cgroup: s/cgroup_subsys_state/cgroup_css/ s/task_subsys_state/task_css/
The names of the two struct cgroup_subsys_state accessors -
cgroup_subsys_state() and task_subsys_state() - are somewhat awkward.
The former clashes with the type name and the latter doesn't even
indicate it's somehow related to cgroup.

We're about to revamp large portion of cgroup API, so, let's rename
them so that they're less awkward.  Most per-controller usages of the
accessors are localized in accessor wrappers and given the amount of
scheduled changes, this isn't gonna add any noticeable headache.

Rename cgroup_subsys_state() to cgroup_css() and task_subsys_state()
to task_css().  This patch is pure rename.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-08 20:11:22 -04:00
Michal Hocko 33cb876e94 vmpressure: make sure there are no events queued after memcg is offlined
vmpressure is called synchronously from reclaim where the target_memcg
is guaranteed to be alive but the eventfd is signaled from the work
queue context.  This means that memcg (along with vmpressure structure
which is embedded into it) might go away while the work item is pending
which would result in use-after-release bug.

We have two possible ways how to fix this.  Either vmpressure pins memcg
before it schedules vmpr->work and unpin it in vmpressure_work_fn or
explicitely flush the work item from the css_offline context (as
suggested by Tejun).

This patch implements the later one and it introduces vmpressure_cleanup
which flushes the vmpressure work queue item item.  It hooks into
mem_cgroup_css_offline after the memcg itself is cleaned up.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Tejun Heo <tj@kernel.org>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Li Zefan <lizefan@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-31 14:41:04 -07:00
Michal Hocko 8e0ed445b3 vmpressure: do not check for pending work to prevent from new work
because it is racy and it doesn't give us much anyway as schedule_work
handles this case already.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Tejun Heo <tj@kernel.org>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Li Zefan <lizefan@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-31 14:41:04 -07:00
Michal Hocko 22f2020f84 vmpressure: change vmpressure::sr_lock to spinlock
There is nothing that can sleep inside critical sections protected by
this lock and those sections are really small so there doesn't make much
sense to use mutex for them.  Change the log to a spinlock

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Tejun Heo <tj@kernel.org>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Li Zefan <lizefan@huawei.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-31 14:41:03 -07:00
Anton Vorontsov 70ddf637ee memcg: add memory.pressure_level events
With this patch userland applications that want to maintain the
interactivity/memory allocation cost can use the pressure level
notifications.  The levels are defined like this:

The "low" level means that the system is reclaiming memory for new
allocations.  Monitoring this reclaiming activity might be useful for
maintaining cache level.  Upon notification, the program (typically
"Activity Manager") might analyze vmstat and act in advance (i.e.
prematurely shutdown unimportant services).

The "medium" level means that the system is experiencing medium memory
pressure, the system might be making swap, paging out active file
caches, etc.  Upon this event applications may decide to further analyze
vmstat/zoneinfo/memcg or internal memory usage statistics and free any
resources that can be easily reconstructed or re-read from a disk.

The "critical" level means that the system is actively thrashing, it is
about to out of memory (OOM) or even the in-kernel OOM killer is on its
way to trigger.  Applications should do whatever they can to help the
system.  It might be too late to consult with vmstat or any other
statistics, so it's advisable to take an immediate action.

The events are propagated upward until the event is handled, i.e.  the
events are not pass-through.  Here is what this means: for example you
have three cgroups: A->B->C.  Now you set up an event listener on
cgroups A, B and C, and suppose group C experiences some pressure.  In
this situation, only group C will receive the notification, i.e.  groups
A and B will not receive it.  This is done to avoid excessive
"broadcasting" of messages, which disturbs the system and which is
especially bad if we are low on memory or thrashing.  So, organize the
cgroups wisely, or propagate the events manually (or, ask us to
implement the pass-through events, explaining why would you need them.)

Performance wise, the memory pressure notifications feature itself is
lightweight and does not require much of bookkeeping, in contrast to the
rest of memcg features.  Unfortunately, as of current memcg
implementation, pages accounting is an inseparable part and cannot be
turned off.  The good news is that there are some efforts[1] to improve
the situation; plus, implementing the same, fully API-compatible[2]
interface for CONFIG_MEMCG=n case (e.g.  embedded) is also a viable
option, so it will not require any changes on the userland side.

[1] http://permalink.gmane.org/gmane.linux.kernel.cgroups/6291
[2] http://lkml.org/lkml/2013/2/21/454

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_CGROPUPS=n warnings]
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Leonid Moiseichuk <leonid.moiseichuk@nokia.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29 15:54:38 -07:00