linux-toradex.git/mm/oom_kill.c, branch v3.7

oom: remove deprecated oom_adj

2012-10-09T07:22:24+00:00

The deprecated /proc//oom_adj is scheduled for removal this month.

Signed-off-by: Davidlohr Bueso 
Acked-by: David Rientjes 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, memcg: move all oom handling to memcontrol.c

2012-08-01T01:42:45+00:00

By globally defining check_panic_on_oom(), the memcg oom handler can be
moved entirely to mm/memcontrol.c.  This removes the ugly #ifdef in the
oom killer and cleans up the code.

Signed-off-by: David Rientjes 
Cc: KAMEZAWA Hiroyuki 
Acked-by: Michal Hocko 
Cc: Oleg Nesterov 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, oom: reduce dependency on tasklist_lock

2012-08-01T01:42:44+00:00

Since exiting tasks require write_lock_irq(&tasklist_lock) several times,
try to reduce the amount of time the readside is held for oom kills.  This
makes the interface with the memcg oom handler more consistent since it
now never needs to take tasklist_lock unnecessarily.

The only time the oom killer now takes tasklist_lock is when iterating the
children of the selected task, everything else is protected by
rcu_read_lock().

This requires that a reference to the selected process, p, is grabbed
before calling oom_kill_process().  It may release it and grab a reference
on another one of p's threads if !p->mm, but it also guarantees that it
will release the reference before returning.

[hughd@google.com: fix duplicate put_task_struct()]
Signed-off-by: David Rientjes 
Cc: KAMEZAWA Hiroyuki 
Reviewed-by: Michal Hocko 
Cc: Oleg Nesterov 
Cc: KOSAKI Motohiro 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, memcg: introduce own oom handler to iterate only over its own threads

2012-08-01T01:42:44+00:00

The global oom killer is serialized by the per-zonelist
try_set_zonelist_oom() which is used in the page allocator.  Concurrent
oom kills are thus a rare event and only occur in systems using
mempolicies and with a large number of nodes.

Memory controller oom kills, however, can frequently be concurrent since
there is no serialization once the oom killer is called for oom conditions
in several different memcgs in parallel.

This creates a massive contention on tasklist_lock since the oom killer
requires the readside for the tasklist iteration.  If several memcgs are
calling the oom killer, this lock can be held for a substantial amount of
time, especially if threads continue to enter it as other threads are
exiting.

Since the exit path grabs the writeside of the lock with irqs disabled in
a few different places, this can cause a soft lockup on cpus as a result
of tasklist_lock starvation.

The kernel lacks unfair writelocks, and successful calls to the oom killer
usually result in at least one thread entering the exit path, so an
alternative solution is needed.

This patch introduces a seperate oom handler for memcgs so that they do
not require tasklist_lock for as much time.  Instead, it iterates only
over the threads attached to the oom memcg and grabs a reference to the
selected thread before calling oom_kill_process() to ensure it doesn't
prematurely exit.

This still requires tasklist_lock for the tasklist dump, iterating
children of the selected process, and killing all other threads on the
system sharing the same memory as the selected victim.  So while this
isn't a complete solution to tasklist_lock starvation, it significantly
reduces the amount of time that it is held.

Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Michal Hocko 
Signed-off-by: David Rientjes 
Cc: Oleg Nesterov 
Cc: KOSAKI Motohiro 
Reviewed-by: Sha Zhengju 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, oom: introduce helper function to process threads during scan

2012-08-01T01:42:44+00:00

This patch introduces a helper function to process each thread during the
iteration over the tasklist.  A new return type, enum oom_scan_t, is
defined to determine the future behavior of the iteration:

 - OOM_SCAN_OK: continue scanning the thread and find its badness,

 - OOM_SCAN_CONTINUE: do not consider this thread for oom kill, it's
   ineligible,

 - OOM_SCAN_ABORT: abort the iteration and return, or

 - OOM_SCAN_SELECT: always select this thread with the highest badness
   possible.

There is no functional change with this patch.  This new helper function
will be used in the next patch in the memory controller.

Reviewed-by: KAMEZAWA Hiroyuki 
Acked-by: KOSAKI Motohiro 
Reviewed-by: Michal Hocko 
Signed-off-by: David Rientjes 
Cc: Oleg Nesterov 
Reviewed-by: Sha Zhengju 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: rename config variables

2012-08-01T01:42:43+00:00

Sanity:

CONFIG_CGROUP_MEM_RES_CTLR -> CONFIG_MEMCG
CONFIG_CGROUP_MEM_RES_CTLR_SWAP -> CONFIG_MEMCG_SWAP
CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED -> CONFIG_MEMCG_SWAP_ENABLED
CONFIG_CGROUP_MEM_RES_CTLR_KMEM -> CONFIG_MEMCG_KMEM

[mhocko@suse.cz: fix missed bits]
Cc: Glauber Costa 
Acked-by: Michal Hocko 
Cc: Johannes Weiner 
Cc: KAMEZAWA Hiroyuki 
Cc: Hugh Dickins 
Cc: Tejun Heo 
Cc: Aneesh Kumar K.V 
Cc: David Rientjes 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, oom: replace some information in tasklist dump

2012-08-01T01:42:42+00:00

The number of ptes and swap entries are used in the oom killer's badness
heuristic, so they should be shown in the tasklist dump.

This patch adds those fields and replaces cpu and oom_adj values that are
currently emitted.  Cpu isn't interesting and oom_adj is deprecated and
will be removed later this year, the same information is already displayed
as oom_score_adj which is used internally.

At the same time, make the documentation a little more clear to state this
information is helpful to determine why the oom killer chose the task it
did to kill.

Signed-off-by: David Rientjes 
Cc: KAMEZAWA Hiroyuki 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, oom: fix potential killing of thread that is disabled from oom killing

2012-08-01T01:42:42+00:00

/proc/sys/vm/oom_kill_allocating_task will immediately kill current when
the oom killer is called to avoid a potentially expensive tasklist scan
for large systems.

Currently, however, it is not checking current's oom_score_adj value which
may be OOM_SCORE_ADJ_MIN, meaning that it has been disabled from oom
killing.

This patch avoids killing current in such a condition and simply falls
back to the tasklist scan since memory still needs to be freed.

Signed-off-by: David Rientjes 
Cc: KAMEZAWA Hiroyuki 
Acked-by: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, oom: do not schedule if current has been killed

2012-08-01T01:42:41+00:00

The oom killer currently schedules away from current in an uninterruptible
sleep if it does not have access to memory reserves.  It's possible that
current was killed because it shares memory with the oom killed thread or
because it was killed by the user in the interim, however.

This patch only schedules away from current if it does not have a pending
kill, i.e.  if it does not share memory with the oom killed thread.  It's
possible that it will immediately retry its memory allocation and fail,
but it will immediately be given access to memory reserves if it calls the
oom killer again.

This prevents the delay of memory freeing when threads that share memory
with the oom killed thread get unnecessarily scheduled.

Signed-off-by: David Rientjes 
Cc: Oleg Nesterov 
Acked-by: KOSAKI Motohiro 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: fix kernel-doc warnings

2012-06-20T21:39:36+00:00

Fix kernel-doc warnings such as

  Warning(../mm/page_cgroup.c:432): No description found for parameter 'id'
  Warning(../mm/page_cgroup.c:432): Excess function parameter 'mem' description in 'swap_cgroup_record'

Signed-off-by: Wanpeng Li 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds