linux-toradex.git/kernel/cgroup.c, branch imx-android-r10.4

Android Fix cgroup: Add generic cgroup subsystem permission checks.

2011-07-15T10:30:09+00:00

Change-Id: Ib82f6a716686a3ebb4592112400fc5e4a2ce066c
Signed-off-by: Colin Cross

Android cgroup: Add generic cgroup subsystem permission checks.

2011-07-15T10:29:14+00:00

    Rather than using explicit euid == 0 checks when trying to move
tasks into a cgroup via CFS, move permission checks into each
specific cgroup subsystem. If a subsystem does not specify a
'can_attach' handler, then we fall back to doing our checks the old way.

    This way non-root processes can add arbitrary processes to
a cgroup if all the registered subsystems on that cgroup agree.

    Also change explicit euid == 0 check to CAP_SYS_ADMIN

Signed-off-by: San Mehat

cgroups: alloc_css_id() increments hierarchy depth

2010-06-04T22:21:45+00:00

Child groups should have a greater depth than their parents.  Prior to
this change, the parent would incorrectly report zero memory usage for
child cgroups when use_hierarchy is enabled.

test script:
  mount -t cgroup none /cgroups -o memory
  cd /cgroups
  mkdir cg1

  echo 1 > cg1/memory.use_hierarchy
  mkdir cg1/cg11

  echo $$ > cg1/cg11/tasks
  dd if=/dev/zero of=/tmp/foo bs=1M count=1

  echo
  echo CHILD
  grep cache cg1/cg11/memory.stat

  echo
  echo PARENT
  grep cache cg1/memory.stat

  echo $$ > tasks
  rmdir cg1/cg11 cg1
  cd /
  umount /cgroups

Using fae9c79, a recent patch that changed alloc_css_id() depth computation,
the parent incorrectly reports zero usage:
  root@ubuntu:~# ./test
  1+0 records in
  1+0 records out
  1048576 bytes (1.0 MB) copied, 0.0151844 s, 69.1 MB/s

  CHILD
  cache 1048576
  total_cache 1048576

  PARENT
  cache 0
  total_cache 0

With this patch, the parent correctly includes child usage:
  root@ubuntu:~# ./test
  1+0 records in
  1+0 records out
  1048576 bytes (1.0 MB) copied, 0.0136827 s, 76.6 MB/s

  CHILD
  cache 1052672
  total_cache 1052672

  PARENT
  cache 0
  total_cache 1052672

Signed-off-by: Greg Thelen 
Acked-by: Paul Menage 
Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Li Zefan 
Cc: 		[2.6.34.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: make cftype.unregister_event() void-returning

2010-05-27T16:12:44+00:00

Since we are unable to handle an error returned by
cftype.unregister_event() properly, let's make the callback
void-returning.

mem_cgroup_unregister_event() has been rewritten to be a "never fail"
function.  On mem_cgroup_usage_register_event() we save old buffer for
thresholds array and reuse it in mem_cgroup_usage_unregister_event() to
avoid allocation.

Signed-off-by: Kirill A. Shutemov 
Acked-by: KAMEZAWA Hiroyuki 
Cc: Phil Carmody 
Cc: Balbir Singh 
Cc: Daisuke Nishimura 
Cc: Paul Menage 
Cc: Li Zefan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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

2010-05-20T16:20:59+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (44 commits)
  vlynq: make whole Kconfig-menu dependant on architecture
  add descriptive comment for TIF_MEMDIE task flag declaration.
  EEPROM: max6875: Header file cleanup
  EEPROM: 93cx6: Header file cleanup
  EEPROM: Header file cleanup
  agp: use NULL instead of 0 when pointer is needed
  rtc-v3020: make bitfield unsigned
  PCI: make bitfield unsigned
  jbd2: use NULL instead of 0 when pointer is needed
  cciss: fix shadows sparse warning
  doc: inode uses a mutex instead of a semaphore.
  uml: i386: Avoid redefinition of NR_syscalls
  fix "seperate" typos in comments
  cocbalt_lcdfb: correct sections
  doc: Change urls for sparse
  Powerpc: wii: Fix typo in comment
  i2o: cleanup some exit paths
  Documentation/: it's -> its where appropriate
  UML: Fix compiler warning due to missing task_struct declaration
  UML: add kernel.h include to signal.c
  ...

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2010-05-18T15:27:54+00:00

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (49 commits)
  stop_machine: Move local variable closer to the usage site in cpu_stop_cpu_callback()
  sched, wait: Use wrapper functions
  sched: Remove a stale comment
  ondemand: Make the iowait-is-busy time a sysfs tunable
  ondemand: Solve a big performance issue by counting IOWAIT time as busy
  sched: Intoduce get_cpu_iowait_time_us()
  sched: Eliminate the ts->idle_lastupdate field
  sched: Fold updating of the last_update_time_info into update_ts_time_stats()
  sched: Update the idle statistics in get_cpu_idle_time_us()
  sched: Introduce a function to update the idle statistics
  sched: Add a comment to get_cpu_idle_time_us()
  cpu_stop: add dummy implementation for UP
  sched: Remove rq argument to the tracepoints
  rcu: need barrier() in UP synchronize_sched_expedited()
  sched: correctly place paranioa memory barriers in synchronize_sched_expedited()
  sched: kill paranoia check in synchronize_sched_expedited()
  sched: replace migration_thread with cpu_stop
  stop_machine: reimplement using cpu_stop
  cpu_stop: implement stop_cpu[s]()
  sched: Fix select_idle_sibling() logic in select_task_rq_fair()
  ...

memcg: fix css_is_ancestor() RCU locking

2010-05-12T00:33:42+00:00

Some callers (in memcontrol.c) calls css_is_ancestor() without
rcu_read_lock.  Because css_is_ancestor() has to access RCU protected
data, it should be under rcu_read_lock().

This makes css_is_ancestor() itself does safe access to RCU protected
area.  (At least, "root" can have refcnt==0 if it's not an ancestor of
"child".  So, we need rcu_read_lock().)

Signed-off-by: KAMEZAWA Hiroyuki 
Cc: "Paul E. McKenney" 
Cc: Daisuke Nishimura 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: fix css_id() RCU locking for real

2010-05-12T00:33:42+00:00

Commit ad4ba375373937817404fd92239ef4cadbded23b ("memcg: css_id() must be
called under rcu_read_lock()") modifies memcontol.c for fixing RCU check
message.  But Andrew Morton pointed out that the fix doesn't seems sane
and it was just for hidining lockdep messages.

This is a patch for do proper things.  Checking again, all places,
accessing without rcu_read_lock, that commit fixies was intentional....
all callers of css_id() has reference count on it.  So, it's not necessary
to be under rcu_read_lock().

Considering again, we can use rcu_dereference_check for css_id().  We know
css->id is valid if css->refcnt > 0.  (css->id never changes and freed
after css->refcnt going to be 0.)

This patch makes use of rcu_dereference_check() in css_id/depth and remove
unnecessary rcu-read-lock added by the commit.

Signed-off-by: KAMEZAWA Hiroyuki 
Cc: "Paul E. McKenney" 
Cc: Daisuke Nishimura 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched, wait: Use wrapper functions

2010-05-11T15:43:58+00:00

epoll should not touch flags in wait_queue_t. This patch introduces a new
function __add_wait_queue_exclusive(), for the users, who use wait queue as a
LIFO queue.

__add_wait_queue_tail_exclusive() is introduced too instead of
add_wait_queue_exclusive_locked(). remove_wait_queue_locked() is removed, as
it is a duplicate of __remove_wait_queue(), disliked by users, and with less
users.

Signed-off-by: Changli Gao 
Signed-off-by: Peter Zijlstra 
Cc: Alexander Viro 
Cc: Paul Menage 
Cc: Li Zefan 
Cc: Davide Libenzi 
Cc: 
LKML-Reference: <1273214006-2979-1-git-send-email-xiaosuo@gmail.com>
Signed-off-by: Ingo Molnar

cgroup: Fix an RCU warning in alloc_css_id()

2010-05-04T16:25:00+00:00

With CONFIG_PROVE_RCU=y, a warning can be triggered:

  # mount -t cgroup -o memory xxx /mnt
  # mkdir /mnt/0

...
kernel/cgroup.c:4442 invoked rcu_dereference_check() without protection!
...

This is a false-positive. It's safe to directly access parent_css->id.

Signed-off-by: Li Zefan 
Signed-off-by: Paul E. McKenney