linux-toradex.git/Documentation/cgroups, branch v3.5

memcg: move charges to root cgroup if use_hierarchy=0

2012-05-29T23:22:27+00:00

Presently, at removal of cgroup, ->pre_destroy() is called and moves
charges to the parent cgroup.  A major reason for returning -EBUSY from
->pre_destroy() is that the 'moving' hits the parent's resource
limitation.  It happens only when use_hierarchy=0.

Considering use_hierarchy=0, all cgroups should be flat.  So, no one
cannot justify moving charges to parent...parent and children are in flat
configuration, not hierarchical.

This patch modifes the code to move charges to the root cgroup at
rmdir/force_empty if use_hierarchy==0.  This will much simplify rmdir()
and reduce error in ->pre_destroy.

Signed-off-by: KAMEZAWA Hiroyuki 
Cc: Aneesh Kumar K.V 
Cc: Michal Hocko 
Cc: Johannes Weiner 
Cc: Frederic Weisbecker 
Cc: Ying Han 
Cc: Glauber Costa 
Reviewed-by: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rescounters: add res_counter_uncharge_until()

2012-05-29T23:22:27+00:00

When killing a res_counter which is a child of other counter, we need to
do

	res_counter_uncharge(child, xxx)
	res_counter_charge(parent, xxx)

This is not atomic and wastes CPU.  This patch adds
res_counter_uncharge_until().  This function's uncharge propagates to
ancestors until specified res_counter.

	res_counter_uncharge_until(child, parent, xxx)

Now the operation is atomic and efficient.

Signed-off-by: Frederic Weisbecker 
Signed-off-by: KAMEZAWA Hiroyuki 
Cc: Aneesh Kumar K.V 
Cc: Michal Hocko 
Cc: Johannes Weiner 
Cc: Ying Han 
Cc: Glauber Costa 
Reviewed-by: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: fix/change behavior of shared anon at moving task

2012-05-29T23:22:24+00:00

This patch changes memcg's behavior at task_move().

At task_move(), the kernel scans a task's page table and move the changes
for mapped pages from source cgroup to target cgroup.  There has been a
bug at handling shared anonymous pages for a long time.

Before patch:
  - The spec says 'shared anonymous pages are not moved.'
  - The implementation was 'shared anonymoys pages may be moved'.
    If page_mapcount <=2, shared anonymous pages's charge were moved.

After patch:
  - The spec says 'all anonymous pages are moved'.
  - The implementation is 'all anonymous pages are moved'.

Considering usage of memcg, this will not affect user's experience.
'shared anonymous' pages only exists between a tree of processes which
don't do exec().  Moving one of process without exec() seems not sane.
For example, libcgroup will not be affected by this change.  (Anyway, no
one noticed the implementation for a long time...)

Below is a discussion log:

 - current spec/implementation are complex
 - Now, shared file caches are moved
 - It adds unclear check as page_mapcount(). To do correct check,
   we should check swap users, etc.
 - No one notice this implementation behavior. So, no one get benefit
   from the design.
 - In general, once task is moved to a cgroup for running, it will not
   be moved....
 - Finally, we have control knob as memory.move_charge_at_immigrate.

Here is a patch to allow moving shared pages, completely. This makes
memcg simpler and fix current broken code.

Suggested-by: Hugh Dickins 
Signed-off-by: KAMEZAWA Hiroyuki 
Acked-by: Michal Hocko 
Cc: Johannes Weiner 
Cc: Naoya Horiguchi 
Cc: Glauber Costa 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: memcg: future proof hierarchical statistics documentation

2012-05-29T23:22:20+00:00

The hierarchical versions of per-memcg counters in memory.stat are all
calculated the same way and are all named total_.

Documenting the pattern is easier for maintenance than listing each
counter twice.

Signed-off-by: Johannes Weiner 
Acked-by: Michal Hocko 
Acked-by: KOSAKI Motohiro 
Acked-by: Ying Han 
Randy Dunlap 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2012-05-23T00:40:19+00:00

Pull cgroup updates from Tejun Heo:
 "cgroup file type addition / removal is updated so that file types are
  added and removed instead of individual files so that dynamic file
  type addition / removal can be implemented by cgroup and used by
  controllers.  blkio controller changes which will come through block
  tree are dependent on this.  Other changes include res_counter cleanup
  and disallowing kthread / PF_THREAD_BOUND threads to be attached to
  non-root cgroups.

  There's a reported bug with the file type addition / removal handling
  which can lead to oops on cgroup umount.  The issue is being looked
  into.  It shouldn't cause problems for most setups and isn't a
  security concern."

Fix up trivial conflict in Documentation/feature-removal-schedule.txt

* 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
  res_counter: Account max_usage when calling res_counter_charge_nofail()
  res_counter: Merge res_counter_charge and res_counter_charge_nofail
  cgroups: disallow attaching kthreadd or PF_THREAD_BOUND threads
  cgroup: remove cgroup_subsys->populate()
  cgroup: get rid of populate for memcg
  cgroup: pass struct mem_cgroup instead of struct cgroup to socket memcg
  cgroup: make css->refcnt clearing on cgroup removal optional
  cgroup: use negative bias on css->refcnt to block css_tryget()
  cgroup: implement cgroup_rm_cftypes()
  cgroup: introduce struct cfent
  cgroup: relocate __d_cgrp() and __d_cft()
  cgroup: remove cgroup_add_file[s]()
  cgroup: convert memcg controller to the new cftype interface
  memcg: always create memsw files if CONFIG_CGROUP_MEM_RES_CTLR_SWAP
  cgroup: convert all non-memcg controllers to the new cftype interface
  cgroup: relocate cftype and cgroup_subsys definitions in controllers
  cgroup: merge cft_release_agent cftype array into the base files array
  cgroup: implement cgroup_add_cftypes() and friends
  cgroup: build list of all cgroups under a given cgroupfs_root
  cgroup: move cgroup_clear_directory() call out of cgroup_populate_dir()
  ...

res_counter: Merge res_counter_charge and res_counter_charge_nofail

2012-04-27T21:36:45+00:00

These two functions do almost the same thing and duplicate some code.
Merge their implementation into a single common function.
res_counter_charge_locked() takes one more parameter but it doesn't seem
to be used outside res_counter.c yet anyway.

There is no (intended) change in the behaviour.

Signed-off-by: Frederic Weisbecker 
Signed-off-by: Tejun Heo 
Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Glauber Costa 
Acked-by: Kirill A. Shutemov 
Cc: Li Zefan

memcg: fix up documentation on global LRU

2012-04-12T20:12:11+00:00

In v3.3-rc1, the global LRU was removed in commit 925b7673cce3 ("mm:
make per-memcg LRU lists exclusive").  The patch fixes up the memcg
docs.

I left the swap session to someone who has better understanding of
'memory+swap'.

Signed-off-by: Ying Han 
Acked-by: Michal Hocko 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

documentation: remove references to cpu_*_map.

2012-03-29T05:08:31+00:00

This has been obsolescent for a while, fix documentation and
misc comments.

Signed-off-by: Rusty Russell

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2012-03-21T04:12:50+00:00

Pull trivial tree from Jiri Kosina:
 "It's indeed trivial -- mostly documentation updates and a bunch of
  typo fixes from Masanari.

  There are also several linux/version.h include removals from Jesper."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (101 commits)
  kcore: fix spelling in read_kcore() comment
  constify struct pci_dev * in obvious cases
  Revert "char: Fix typo in viotape.c"
  init: fix wording error in mm_init comment
  usb: gadget: Kconfig: fix typo for 'different'
  Revert "power, max8998: Include linux/module.h just once in drivers/power/max8998_charger.c"
  writeback: fix fn name in writeback_inodes_sb_nr_if_idle() comment header
  writeback: fix typo in the writeback_control comment
  Documentation: Fix multiple typo in Documentation
  tpm_tis: fix tis_lock with respect to RCU
  Revert "media: Fix typo in mixer_drv.c and hdmi_drv.c"
  Doc: Update numastat.txt
  qla4xxx: Add missing spaces to error messages
  compiler.h: Fix typo
  security: struct security_operations kerneldoc fix
  Documentation: broken URL in libata.tmpl
  Documentation: broken URL in filesystems.tmpl
  mtd: simplify return logic in do_map_probe()
  mm: fix comment typo of truncate_inode_pages_range
  power: bq27x00: Fix typos in comment
  ...

Documentation: Fix multiple typo in Documentation

2012-03-07T15:08:24+00:00

Signed-off-by: Masanari Iida 
Acked-by: Randy Dunlap 
Signed-off-by: Jiri Kosina