Commit Graph

480853 Commits

Author SHA1 Message Date
Wanpeng Li
308a623a40 sched/rt: Clean up check_preempt_equal_prio()
This patch checks if current can be pushed/pulled somewhere else
in advance to make logic clear, the same behavior as dl class.

- If current can't be migrated, useless to reschedule, let's hope
  task can move out.
- If task is migratable, so let's not schedule it and see if it
  can be pushed or pulled somewhere else.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414708776-124078-1-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:52 +01:00
Juri Lelli
75e23e49db sched/core: Use dl_bw_of() under rcu_read_lock_sched()
As per commit f10e00f4bf ("sched/dl: Use dl_bw_of() under
rcu_read_lock_sched()"), dl_bw_of() has to be protected by
rcu_read_lock_sched().

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414497286-28824-1-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:52 +01:00
Yao Dongdong
9f96742a13 sched: Check if we got a shallowest_idle_cpu before searching for least_loaded_cpu
Idle cpu is idler than non-idle cpu, so we needn't search for least_loaded_cpu
after we have found an idle cpu.

Signed-off-by: Yao Dongdong <yaodongdong@huawei.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414469286-6023-1-git-send-email-yaodongdong@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:51 +01:00
Kirill Tkhai
67dfa1b756 sched/deadline: Implement cancel_dl_timer() to use in switched_from_dl()
Currently used hrtimer_try_to_cancel() is racy:

raw_spin_lock(&rq->lock)
...                            dl_task_timer                 raw_spin_lock(&rq->lock)
...                               raw_spin_lock(&rq->lock)   ...
   switched_from_dl()             ...                        ...
      hrtimer_try_to_cancel()     ...                        ...
   switched_to_fair()             ...                        ...
...                               ...                        ...
...                               ...                        ...
raw_spin_unlock(&rq->lock)        ...                        (asquired)
...                               ...                        ...
...                               ...                        ...
do_exit()                         ...                        ...
   schedule()                     ...                        ...
      raw_spin_lock(&rq->lock)    ...                        raw_spin_unlock(&rq->lock)
      ...                         ...                        ...
      raw_spin_unlock(&rq->lock)  ...                        raw_spin_lock(&rq->lock)
      ...                         ...                        (asquired)
      put_task_struct()           ...                        ...
          free_task_struct()      ...                        ...
      ...                         ...                        raw_spin_unlock(&rq->lock)
...                               (asquired)                 ...
...                               ...                        ...
...                               (use after free)           ...

So, let's implement 100% guaranteed way to cancel the timer and let's
be sure we are safe even in very unlikely situations.

rq unlocking does not limit the area of switched_from_dl() use, because
this has already been possible in pull_dl_task() below.

Let's consider the safety of of this unlocking. New code in the patch
is working when hrtimer_try_to_cancel() fails. This means the callback
is running. In this case hrtimer_cancel() is just waiting till the
callback is finished. Two

1) Since we are in switched_from_dl(), new class is not dl_sched_class and
new prio is not less MAX_DL_PRIO. So, the callback returns early; it's
right after !dl_task() check. After that hrtimer_cancel() returns back too.

The above is:

raw_spin_lock(rq->lock);                  ...
...                                       dl_task_timer()
...                                          raw_spin_lock(rq->lock);
   switched_from_dl()                        ...
       hrtimer_try_to_cancel()               ...
          raw_spin_unlock(rq->lock);         ...
          hrtimer_cancel()                   ...
          ...                                raw_spin_unlock(rq->lock);
          ...                                return HRTIMER_NORESTART;
          ...                             ...
          raw_spin_lock(rq->lock);        ...

2) But the below is also possible:
                                   dl_task_timer()
                                      raw_spin_lock(rq->lock);
                                      ...
                                      raw_spin_unlock(rq->lock);
raw_spin_lock(rq->lock);              ...
   switched_from_dl()                 ...
       hrtimer_try_to_cancel()        ...
       ...                            return HRTIMER_NORESTART;
       raw_spin_unlock(rq->lock);  ...
       hrtimer_cancel();           ...
       raw_spin_lock(rq->lock);    ...

In this case hrtimer_cancel() returns immediately. Very unlikely case,
just to mention.

Nobody can manipulate the task, because check_class_changed() is
always called with pi_lock locked. Nobody can force the task to
participate in (concurrent) priority inheritance schemes (the same reason).

All concurrent task operations require pi_lock, which is held by us.
No deadlocks with dl_task_timer() are possible, because it returns
right after !dl_task() check (it does nothing).

If we receive a new dl_task during the time of unlocked rq, we just
don't have to do pull_dl_task() in switched_from_dl() further.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
[ Added comments]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414420852.19914.186.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:50 +01:00
Peter Zijlstra
e7097e8bd0 sched: Use WARN_ONCE for the might_sleep() TASK_RUNNING test
In some cases this can trigger a true flood of output.

Requested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:49 +01:00
Peter Zijlstra
ff960a7317 netdev, sched/wait: Fix sleeping inside wait event
rtnl_lock_unregistering*() take rtnl_lock() -- a mutex -- inside a
wait loop. The wait loop relies on current->state to function, but so
does mutex_lock(), nesting them makes for the inner to destroy the
outer state.

Fix this using the new wait_woken() bits.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Cong Wang <cwang@twopensource.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jerry Chu <hkchu@google.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Cc: sfeldma@cumulusnetworks.com <sfeldma@cumulusnetworks.com>
Cc: stephen hemminger <stephen@networkplumber.org>
Cc: Tom Gundersen <teg@jklm.no>
Cc: Tom Herbert <therbert@google.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Vlad Yasevich <vyasevic@redhat.com>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20141029173110.GE15602@worktop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:48 +01:00
Peter Zijlstra
eedf7e47da rfcomm, sched/wait: Fix broken wait construct
rfcomm_run() is a tad broken in that is has a nested wait loop. One
cannot rely on p->state for the outer wait because the inner wait will
overwrite it.

Fix this using the new wait_woken() facility.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Alexander Holler <holler@ahsoftware.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Joe Perches <joe@perches.com>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Libor Pechacek <lpechacek@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Vignesh Raman <Vignesh_Raman@mentor.com>
Cc: linux-bluetooth@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:47 +01:00
Peter Zijlstra
6b55fc63f4 audit, sched/wait: Fixup kauditd_thread() wait loop
The kauditd_thread wait loop is a bit iffy; it has a number of problems:

 - calls try_to_freeze() before schedule(); you typically want the
   thread to re-evaluate the sleep condition when unfreezing, also
   freeze_task() issues a wakeup.

 - it unconditionally does the {add,remove}_wait_queue(), even when the
   sleep condition is false.

Use wait_event_freezable() that does the right thing.

Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: oleg@redhat.com
Cc: Eric Paris <eparis@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141002102251.GA6324@worktop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:47 +01:00
Peter Zijlstra (Intel)
5d4d565824 sched/wait: Remove wait_event_freezekillable()
There is no user.. make it go away.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: oleg@redhat.com
Cc: Rafael Wysocki <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:46 +01:00
Peter Zijlstra
36df04bc52 sched/wait: Reimplement wait_event_freezable()
Provide better implementations of wait_event_freezable() APIs.

The problem is with freezer_do_not_count(), it hides the thread from
the freezer, even though this thread might not actually freeze/sleep
at all.

Cc: oleg@redhat.com
Cc: Rafael Wysocki <rjw@rjwysocki.net>

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-d86fz1jmso9wjxa8jfpinp8o@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:45 +01:00
Peter Zijlstra
cb6538e740 sched/wait: Fix a kthread race with wait_woken()
There is a race between kthread_stop() and the new wait_woken() that
can result in a lack of progress.

CPU 0                                    | CPU 1
                                         |
rfcomm_run()                             | kthread_stop()
  ...                                    |
  if (!test_bit(KTHREAD_SHOULD_STOP))    |
                                         |   set_bit(KTHREAD_SHOULD_STOP)
                                         |   wake_up_process()
    wait_woken()                         |   wait_for_completion()
      set_current_state(INTERRUPTIBLE)   |
      if (!WQ_FLAG_WOKEN)                |
        schedule_timeout()               |
                                         |

After which both tasks will wait.. forever.

Fix this by having wait_woken() check for kthread_should_stop() but
only for kthreads (obviously).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:44 +01:00
Peter Zijlstra
3427445afd sched: Exclude cond_resched() from nested sleep test
cond_resched() is a preemption point, not strictly a blocking
primitive, so exclude it from the ->state test.

In particular, preemption preserves task_struct::state.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Cc: Alex Elder <alex.elder@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Axel Lin <axel.lin@ingics.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140924082242.656559952@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:56:57 +01:00
Peter Zijlstra
8eb23b9f35 sched: Debug nested sleeps
Validate we call might_sleep() with TASK_RUNNING, which catches places
where we nest blocking primitives, eg. mutex usage in a wait loop.

Since all blocking is arranged through task_struct::state, nesting
this will cause the inner primitive to set TASK_RUNNING and the outer
will thus not block.

Another observed problem is calling a blocking function from
schedule()->sched_submit_work()->blk_schedule_flush_plug() which will
then destroy the task state for the actual __schedule() call that
comes after it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140924082242.591637616@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:56:52 +01:00
Peter Zijlstra
26cabd3125 sched, net: Clean up sk_wait_event() vs. might_sleep()
WARNING: CPU: 1 PID: 1744 at kernel/sched/core.c:7104 __might_sleep+0x58/0x90()
do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff81070e10>] prepare_to_wait+0x50 /0xa0

 [<ffffffff8105bc38>] __might_sleep+0x58/0x90
 [<ffffffff8148c671>] lock_sock_nested+0x31/0xb0
 [<ffffffff81498aaa>] sk_stream_wait_memory+0x18a/0x2d0

Which is a false positive because sk_wait_event() will already have
TASK_RUNNING at that point if it would've gone through
schedule_timeout().

So annotate with sched_annotate_sleep(); which goes away on !DEBUG builds.

Reported-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140924082242.524407432@infradead.org
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: netdev@vger.kernel.org
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:56:37 +01:00
Peter Zijlstra
3c9b2c3d64 sched, modules: Fix nested sleep in add_unformed_module()
This is a genuine bug in add_unformed_module(), we cannot use blocking
primitives inside a wait loop.

So rewrite the wait_event_interruptible() usage to use the fresh
wait_woken() stuff.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20140924082242.458562904@infradead.org
[ So this is probably complex to backport and the race wasn't reported AFAIK,
  so not marked for -stable. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:56:30 +01:00
Peter Zijlstra
7d4d26966e sched, smp: Correctly deal with nested sleeps
smp_hotplug_thread::{setup,unpark} functions can sleep too, so be
consistent and do the same for all callbacks.

 __might_sleep+0x74/0x80
 kmem_cache_alloc_trace+0x4e/0x1c0
 perf_event_alloc+0x55/0x450
 perf_event_create_kernel_counter+0x2f/0x100
 watchdog_nmi_enable+0x8d/0x160
 watchdog_enable+0x45/0x90
 smpboot_thread_fn+0xec/0x2b0
 kthread+0xe4/0x100
 ret_from_fork+0x7c/0xb0

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140924082242.392279328@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:56:24 +01:00
Peter Zijlstra
97d9e28d1a sched, tty: Deal with nested sleeps
n_tty_{read,write} are wait loops with sleeps in. Wait loops rely on
task_struct::state and sleeps do too, since that's the only means of
actually sleeping. Therefore the nested sleeps destroy the wait loop
state.

Fix this by using the new woken_wake_function and wait_woken() stuff,
which registers wakeups in wait and thereby allows shrinking the
task_state::state changes to the actual sleep part.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/20140924082242.323011233@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:56:10 +01:00
Peter Zijlstra
e23738a730 sched, inotify: Deal with nested sleeps
inotify_read is a wait loop with sleeps in. Wait loops rely on
task_struct::state and sleeps do too, since that's the only means of
actually sleeping. Therefore the nested sleeps destroy the wait loop
state and the wait loop breaks the sleep functions that assume
TASK_RUNNING (mutex_lock).

Fix this by using the new woken_wake_function and wait_woken() stuff,
which registers wakeups in wait and thereby allows shrinking the
task_state::state changes to the actual sleep part.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: Robert Love <rlove@rlove.org>
Cc: Eric Paris <eparis@parisplace.org>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20140924082242.254858080@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:55:37 +01:00
Peter Zijlstra
1029a2b52c sched, exit: Deal with nested sleeps
do_wait() is a big wait loop, but we set TASK_RUNNING too late; we end
up calling potential sleeps before we reset it.

Not strictly a bug since we're guaranteed to exit the loop and not
call schedule(); put in annotations to quiet might_sleep().

 WARNING: CPU: 0 PID: 1 at ../kernel/sched/core.c:7123 __might_sleep+0x7e/0x90()
 do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff8109a788>] do_wait+0x88/0x270

 Call Trace:
  [<ffffffff81694991>] dump_stack+0x4e/0x7a
  [<ffffffff8109877c>] warn_slowpath_common+0x8c/0xc0
  [<ffffffff8109886c>] warn_slowpath_fmt+0x4c/0x50
  [<ffffffff810bca6e>] __might_sleep+0x7e/0x90
  [<ffffffff811a1c15>] might_fault+0x55/0xb0
  [<ffffffff8109a3fb>] wait_consider_task+0x90b/0xc10
  [<ffffffff8109a804>] do_wait+0x104/0x270
  [<ffffffff8109b837>] SyS_wait4+0x77/0x100
  [<ffffffff8169d692>] system_call_fastpath+0x16/0x1b

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: umgwanakikbuti@gmail.com
Cc: ilya.dryomov@inktank.com
Cc: Alex Elder <alex.elder@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Axel Lin <axel.lin@ingics.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Guillaume Morin <guillaume@morinfr.org>
Cc: Ionut Alexa <ionut.m.alexa@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140924082242.186408915@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:55:30 +01:00
Peter Zijlstra
e22b886a8a sched/wait: Add might_sleep() checks
Add more might_sleep() checks, suppose someone put a wait_event() like
thing in a wait loop..

Can't put might_sleep() in ___wait_event() because there's the locked
primitives which call ___wait_event() with locks held.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140924082242.119255706@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:55:23 +01:00
Peter Zijlstra
61ada528de sched/wait: Provide infrastructure to deal with nested blocking
There are a few places that call blocking primitives from wait loops,
provide infrastructure to support this without the typical
task_struct::state collision.

We record the wakeup in wait_queue_t::flags which leaves
task_struct::state free to be used by others.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140924082242.051202318@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:55:15 +01:00
Peter Zijlstra
6f942a1f26 locking/mutex: Don't assume TASK_RUNNING
We're going to make might_sleep() test for TASK_RUNNING, because
blocking without TASK_RUNNING will destroy the task state by setting
it to TASK_RUNNING.

There are a few occasions where its 'valid' to call blocking
primitives (and mutex_lock in particular) and not have TASK_RUNNING,
typically such cases are right before we set TASK_RUNNING anyhow.

Robustify the code by not assuming this; this has the beneficial side
effect of allowing optional code emission for fixing the above
might_sleep() false positives.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140924082241.988560063@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:55:08 +01:00
Wanpeng Li
f4e9d94a5b sched/deadline: Don't balance during wakeup if wakee is pinned
Use nr_cpus_allowed to bail from select_task_rq() when only one cpu
can be used, and saves some cycles for pinned tasks.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413253360-5318-2-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:48:02 +01:00
Wanpeng Li
1d7e974cbf sched/deadline: Don't check SD_BALANCE_FORK
There is no need to do balance during fork since SCHED_DEADLINE
tasks can't fork. This patch avoid the SD_BALANCE_FORK check.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1413253360-5318-1-git-send-email-wanpeng.li@linux.intel.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:48:01 +01:00
Juri Lelli
f82f80426f sched/deadline: Ensure that updates to exclusive cpusets don't break AC
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 <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: cgroups@vger.kernel.org
Link: http://lkml.kernel.org/r/5433E6AF.5080105@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:48:00 +01:00
Juri Lelli
7f51412a41 sched/deadline: Fix bandwidth check/update when migrating tasks between exclusive cpusets
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 <daniel.wagner@bmw-carit.de>
Reported-by: Vincent Legout <vincent@legout.info>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Cc: Fabio Checconi <fchecconi@gmail.com>
Cc: michael@amarulasolutions.com
Cc: luca.abeni@unitn.it
Cc: Li Zefan <lizefan@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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 <mingo@kernel.org>
2014-10-28 10:47:58 +01:00
Wanpeng Li
d9aade7ae1 sched/deadline: Do not try to push tasks if pinned task switches to dl
As Kirill mentioned (https://lkml.org/lkml/2013/1/29/118):

 | If rq has already had 2 or more pushable tasks and we try to add a
 | pinned task then call of push_rt_task will just waste a time.

Just switched pinned task is not able to be pushed. If the rq has had
several dl tasks before they have already been considered as candidates
to be pushed (or pulled). This patch implements the same behavior as rt
class which introduced by commit 1044791755 ("sched/rt: Do not try to
push tasks if pinned task switches to RT").

Suggested-by: Kirill V Tkhai <tkhai@yandex.ru>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413938203-224610-1-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:57 +01:00
Oleg Nesterov
e2336f6e51 sched: Kill task_preempt_count()
task_preempt_count() is pointless if preemption counter is per-cpu,
currently this is x86 only. It is only valid if the task is not
running, and even in this case the only info it can provide is the
state of PREEMPT_ACTIVE bit.

Change its single caller to check p->on_rq instead, this should be
the same if p->state != TASK_RUNNING, and kill this helper.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Alexander Graf <agraf@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/20141008183348.GC17495@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:56 +01:00
Oleg Nesterov
dfa50b605c sched: Make finish_task_switch() return 'struct rq *'
Both callers of finish_task_switch() need to recalculate this_rq()
and pass it as an argument, plus __schedule() does this again after
context_switch().

It would be simpler to call this_rq() once in finish_task_switch()
and return the this rq to the callers.

Note: probably "int cpu" in __schedule() should die; it is not used
and both rcu_note_context_switch() and wq_worker_sleeping() do not
really need this argument.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141009193232.GB5408@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:55 +01:00
Oleg Nesterov
1a43a14a5b sched: Fix schedule_tail() to disable preemption
finish_task_switch() enables preemption, so post_schedule(rq) can be
called on the wrong (and even dead) CPU. Afaics, nothing really bad
can happen, but in this case we can wrongly clear rq->post_schedule
on that CPU. And this simply looks wrong in any case.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141008193644.GA32055@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:54 +01:00
Oleg Nesterov
8f9fbf092c sched: Fix the PREEMPT_ACTIVE check in __trace_sched_switch_state()
task_preempt_count() has nothing to do with the actual preempt counter,
thread_info->saved_preempt_count is only valid right after switch_to().

__trace_sched_switch_state() can use preempt_count(), prev is still the
current task when trace_sched_switch() is called.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
[ Added BUG_ON(). ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20141007195108.GB28002@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:53 +01:00
Rik van Riel
9de05d4871 sched/numa: Check all nodes when placing a pseudo-interleaved group
In pseudo-interleaved numa_groups, all tasks try to relocate to
the group's preferred_nid.  When a group is spread across multiple
NUMA nodes, this can lead to tasks swapping their location with
other tasks inside the same group, instead of swapping location with
tasks from other NUMA groups. This can keep NUMA groups from converging.

Examining all nodes, when dealing with a task in a pseudo-interleaved
NUMA group, avoids this problem. Note that only CPUs in nodes that
improve the task or group score are examined, so the loop isn't too
bad.

Tested-by: Vinod Chegu <chegu_vinod@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Vinod Chegu" <chegu_vinod@hp.com>
Cc: mgorman@suse.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141009172747.0d97c38c@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:52 +01:00
Rik van Riel
54009416ac sched/numa: Find the preferred nid with complex NUMA topology
On systems with complex NUMA topologies, the node scoring is adjusted
to allow workloads to converge on nodes that are near each other.

The way a task group's preferred nid is determined needs to be adjusted,
in order for the preferred_nid to be consistent with group_weight scoring.
This ensures that we actually try to converge workloads on adjacent nodes.

Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Chegu Vinod <chegu_vinod@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413530994-9732-6-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:51 +01:00
Rik van Riel
6c6b1193e7 sched/numa: Calculate node scores in complex NUMA topologies
In order to do task placement on systems with complex NUMA topologies,
it is necessary to count the faults on nodes nearby the node that is
being examined for a potential move.

In case of a system with a backplane interconnect, we are dealing with
groups of NUMA nodes; each of the nodes within a group is the same number
of hops away from nodes in other groups in the system. Optimal placement
on this topology is achieved by counting all nearby nodes equally. When
comparing nodes A and B at distance N, nearby nodes are those at distances
smaller than N from nodes A or B.

Placement strategy on a system with a glueless mesh NUMA topology needs
to be different, because there are no natural groups of nodes determined
by the hardware. Instead, when dealing with two nodes A and B at distance
N, N >= 2, there will be intermediate nodes at distance < N from both nodes
A and B. Good placement can be achieved by right shifting the faults on
nearby nodes by the number of hops from the node being scored. In this
context, a nearby node is any node less than the maximum distance in the
system away from the node. Those nodes are skipped for efficiency reasons,
there is no real policy reason to do so.

Placement policy on directly connected NUMA systems is not affected.

Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Chegu Vinod <chegu_vinod@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Link: http://lkml.kernel.org/r/1413530994-9732-5-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:50 +01:00
Rik van Riel
7bd953206b sched/numa: Prepare for complex topology placement
Preparatory patch for adding NUMA placement on systems with
complex NUMA topology. Also fix a potential divide by zero
in group_weight()

Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Chegu Vinod <chegu_vinod@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413530994-9732-4-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:49 +01:00
Rik van Riel
e3fe70b1f7 sched/numa: Classify the NUMA topology of a system
Smaller NUMA systems tend to have all NUMA nodes directly connected
to each other. This includes the degenerate case of a system with just
one node, ie. a non-NUMA system.

Larger systems can have two kinds of NUMA topology, which affects how
tasks and memory should be placed on the system.

On glueless mesh systems, nodes that are not directly connected to
each other will bounce traffic through intermediary nodes. Task groups
can be run closer to each other by moving tasks from a node to an
intermediary node between it and the task's preferred node.

On NUMA systems with backplane controllers, the intermediary hops
are incapable of running programs. This creates "islands" of nodes
that are at an equal distance to anywhere else in the system.

Each kind of topology requires a slightly different placement
algorithm; this patch provides the mechanism to detect the kind
of NUMA topology of a system.

Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Chegu Vinod <chegu_vinod@hp.com>
[ Changed to use kernel/sched/sched.h ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Link: http://lkml.kernel.org/r/1413530994-9732-3-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:48 +01:00
Rik van Riel
9942f79baa sched/numa: Export info needed for NUMA balancing on complex topologies
Export some information that is necessary to do placement of
tasks on systems with multi-level NUMA topologies.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413530994-9732-2-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:47:47 +01:00
Kirill Tkhai
f3a7e1a9c4 sched/dl: Fix preemption checks
1) switched_to_dl() check is wrong. We reschedule only
   if rq->curr is deadline task, and we do not reschedule
   if it's a lower priority task. But we must always
   preempt a task of other classes.

2) dl_task_timer():
   Policy does not change in case of priority inheritance.
   rt_mutex_setprio() changes prio, while policy remains old.

So we lose some balancing logic in dl_task_timer() and
switched_to_dl() when we check policy instead of priority. Boosted
task may be rq->curr.

(I didn't change switched_from_dl() because no check is necessary
there at all).

I've looked at this place(switched_to_dl) several times and even fixed
this function, but found just now...  I suppose some performance tests
may work better after this.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413909356.19914.128.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:10 +01:00
Chen Hanxiao
fcd964dda5 sched: Update comments for CLONE_NEWNS
Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/1412674147-8941-1-git-send-email-chenhanxiao@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:08 +01:00
Oleg Nesterov
009f60e276 sched: stop the unbound recursion in preempt_schedule_context()
preempt_schedule_context() does preempt_enable_notrace() at the end
and this can call the same function again; exception_exit() is heavy
and it is quite possible that need-resched is true again.

1. Change this code to dec preempt_count() and check need_resched()
   by hand.

2. As Linus suggested, we can use the PREEMPT_ACTIVE bit and avoid
   the enable/disable dance around __schedule(). But in this case
   we need to move into sched/core.c.

3. Cosmetic, but x86 forgets to declare this function. This doesn't
   really matter because it is only called by asm helpers, still it
   make sense to add the declaration into asm/preempt.h to match
   preempt_schedule().

Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Chuck Ebbert <cebbert.lkml@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20141005202322.GB27962@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:05 +01:00
Kirill Tkhai
6419265899 sched/fair: Fix division by zero sysctl_numa_balancing_scan_size
File /proc/sys/kernel/numa_balancing_scan_size_mb allows writing of zero.

This bash command reproduces problem:

$ while :; do echo 0 > /proc/sys/kernel/numa_balancing_scan_size_mb; \
	   echo 256 > /proc/sys/kernel/numa_balancing_scan_size_mb; done

	divide error: 0000 [#1] SMP
	Modules linked in:
	CPU: 0 PID: 24112 Comm: bash Not tainted 3.17.0+ #8
	Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
	task: ffff88013c852600 ti: ffff880037a68000 task.ti: ffff880037a68000
	RIP: 0010:[<ffffffff81074191>]  [<ffffffff81074191>] task_scan_min+0x21/0x50
	RSP: 0000:ffff880037a6bce0  EFLAGS: 00010246
	RAX: 0000000000000a00 RBX: 00000000000003e8 RCX: 0000000000000000
	RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88013c852600
	RBP: ffff880037a6bcf0 R08: 0000000000000001 R09: 0000000000015c90
	R10: ffff880239bf6c00 R11: 0000000000000016 R12: 0000000000003fff
	R13: ffff88013c852600 R14: ffffea0008d1b000 R15: 0000000000000003
	FS:  00007f12bb048700(0000) GS:ffff88007da00000(0000) knlGS:0000000000000000
	CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
	CR2: 0000000001505678 CR3: 0000000234770000 CR4: 00000000000006f0
	Stack:
	 ffff88013c852600 0000000000003fff ffff880037a6bd18 ffffffff810741d1
	 ffff88013c852600 0000000000003fff 000000000002bfff ffff880037a6bda8
	 ffffffff81077ef7 ffffea0008a56d40 0000000000000001 0000000000000001
	Call Trace:
	 [<ffffffff810741d1>] task_scan_max+0x11/0x40
	 [<ffffffff81077ef7>] task_numa_fault+0x1f7/0xae0
	 [<ffffffff8115a896>] ? migrate_misplaced_page+0x276/0x300
	 [<ffffffff81134a4d>] handle_mm_fault+0x62d/0xba0
	 [<ffffffff8103e2f1>] __do_page_fault+0x191/0x510
	 [<ffffffff81030122>] ? native_smp_send_reschedule+0x42/0x60
	 [<ffffffff8106dc00>] ? check_preempt_curr+0x80/0xa0
	 [<ffffffff8107092c>] ? wake_up_new_task+0x11c/0x1a0
	 [<ffffffff8104887d>] ? do_fork+0x14d/0x340
	 [<ffffffff811799bb>] ? get_unused_fd_flags+0x2b/0x30
	 [<ffffffff811799df>] ? __fd_install+0x1f/0x60
	 [<ffffffff8103e67c>] do_page_fault+0xc/0x10
	 [<ffffffff8150d322>] page_fault+0x22/0x30
	RIP  [<ffffffff81074191>] task_scan_min+0x21/0x50
	RSP <ffff880037a6bce0>
	---[ end trace 9a826d16936c04de ]---

Also fix race in task_scan_min (it depends on compiler behaviour).

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: David Rientjes <rientjes@google.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Link: http://lkml.kernel.org/r/1413455977.24793.78.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:04 +01:00
Yasuaki Ishimatsu
2847c90e1b sched/fair: Care divide error in update_task_scan_period()
While offling node by hot removing memory, the following divide error
occurs:

  divide error: 0000 [#1] SMP
  [...]
  Call Trace:
   [...] handle_mm_fault
   [...] ? try_to_wake_up
   [...] ? wake_up_state
   [...] __do_page_fault
   [...] ? do_futex
   [...] ? put_prev_entity
   [...] ? __switch_to
   [...] do_page_fault
   [...] page_fault
  [...]
  RIP  [<ffffffff810a7081>] task_numa_fault
   RSP <ffff88084eb2bcb0>

The issue occurs as follows:
  1. When page fault occurs and page is allocated from node 1,
     task_struct->numa_faults_buffer_memory[] of node 1 is
     incremented and p->numa_faults_locality[] is also incremented
     as follows:

     o numa_faults_buffer_memory[]       o numa_faults_locality[]
              NR_NUMA_HINT_FAULT_TYPES
             |      0     |     1     |
     ----------------------------------  ----------------------
      node 0 |      0     |     0     |   remote |      0     |
      node 1 |      0     |     1     |   locale |      1     |
     ----------------------------------  ----------------------

  2. node 1 is offlined by hot removing memory.

  3. When page fault occurs, fault_types[] is calculated by using
     p->numa_faults_buffer_memory[] of all online nodes in
     task_numa_placement(). But node 1 was offline by step 2. So
     the fault_types[] is calculated by using only
     p->numa_faults_buffer_memory[] of node 0. So both of fault_types[]
     are set to 0.

  4. The values(0) of fault_types[] pass to update_task_scan_period().

  5. numa_faults_locality[1] is set to 1. So the following division is
     calculated.

        static void update_task_scan_period(struct task_struct *p,
                                unsigned long shared, unsigned long private){
        ...
                ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared));
        }

  6. But both of private and shared are set to 0. So divide error
     occurs here.

The divide error is rare case because the trigger is node offline.
This patch always increments denominator for avoiding divide error.

Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/54475703.8000505@jp.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:03 +01:00
Kirill Tkhai
1effd9f193 sched/numa: Fix unsafe get_task_struct() in task_numa_assign()
Unlocked access to dst_rq->curr in task_numa_compare() is racy.
If curr task is exiting this may be a reason of use-after-free:

task_numa_compare()                    do_exit()
    ...                                        current->flags |= PF_EXITING;
    ...                                    release_task()
    ...                                        ~~delayed_put_task_struct()~~
    ...                                    schedule()
    rcu_read_lock()                        ...
    cur = ACCESS_ONCE(dst_rq->curr)        ...
        ...                                rq->curr = next;
        ...                                    context_switch()
        ...                                        finish_task_switch()
        ...                                            put_task_struct()
        ...                                                __put_task_struct()
        ...                                                    free_task_struct()
        task_numa_assign()                                     ...
            get_task_struct()                                  ...

As noted by Oleg:

  <<The lockless get_task_struct(tsk) is only safe if tsk == current
    and didn't pass exit_notify(), or if this tsk was found on a rcu
    protected list (say, for_each_process() or find_task_by_vpid()).
    IOW, it is only safe if release_task() was not called before we
    take rcu_read_lock(), in this case we can rely on the fact that
    delayed_put_pid() can not drop the (potentially) last reference
    until rcu_read_unlock().

    And as Kirill pointed out task_numa_compare()->task_numa_assign()
    path does get_task_struct(dst_rq->curr) and this is not safe. The
    task_struct itself can't go away, but rcu_read_lock() can't save
    us from the final put_task_struct() in finish_task_switch(); this
    reference goes away without rcu gp>>

The patch provides simple check of PF_EXITING flag. If it's not set,
this guarantees that call_rcu() of delayed_put_task_struct() callback
hasn't happened yet, so we can safely do get_task_struct() in
task_numa_assign().

Locked dst_rq->lock protects from concurrency with the last schedule().
Reusing or unmapping of cur's memory may happen without it.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413962231.19914.130.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:02 +01:00
Juri Lelli
aee38ea954 sched/deadline: Fix races between rt_mutex_setprio() and dl_task_timer()
dl_task_timer() is racy against several paths. Daniel noticed that
the replenishment timer may experience a race condition against an
enqueue_dl_entity() called from rt_mutex_setprio(). With his own
words:

 rt_mutex_setprio() resets p->dl.dl_throttled. So the pattern is:
 start_dl_timer() throttled = 1, rt_mutex_setprio() throlled = 0,
 sched_switch() -> enqueue_task(), dl_task_timer-> enqueue_task()
 throttled is 0

=> BUG_ON(on_dl_rq(dl_se)) fires as the scheduling entity is already
enqueued on the -deadline runqueue.

As we do for the other races, we just bail out in the replenishment
timer code.

Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: vincent@legout.info
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Cc: Fabio Checconi <fchecconi@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414142198-18552-5-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:01 +01:00
Juri Lelli
64be6f1f5f sched/deadline: Don't replenish from a !SCHED_DEADLINE entity
In the deboost path, right after the dl_boosted flag has been
reset, we can currently end up replenishing using -deadline
parameters of a !SCHED_DEADLINE entity. This of course causes
a bug, as those parameters are empty.

In the case depicted above it is safe to simply bail out, as
the deboosted task is going to be back to its original scheduling
class anyway.

Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: vincent@legout.info
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Cc: Fabio Checconi <fchecconi@gmail.com>
Link: http://lkml.kernel.org/r/1414142198-18552-4-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:00 +01:00
Kirill Tkhai
eeb61e53ea sched: Fix race between task_group and sched_task_group
The race may happen when somebody is changing task_group of a forking task.
Child's cgroup is the same as parent's after dup_task_struct() (there just
memory copying). Also, cfs_rq and rt_rq are the same as parent's.

But if parent changes its task_group before it's called cgroup_post_fork(),
we do not reflect this situation on child. Child's cfs_rq and rt_rq remain
the same, while child's task_group changes in cgroup_post_fork().

To fix this we introduce fork() method, which calls sched_move_task() directly.
This function changes sched_task_group on appropriate (also its logic has
no problem with freshly created tasks, so we shouldn't introduce something
special; we are able just to use it).

Possibly, this decides the Burke Libbey's problem: https://lkml.org/lkml/2014/10/24/456

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:45:59 +01:00
Linus Torvalds
cac7f24298 Linux 3.18-rc2 2014-10-26 16:48:41 -07:00
Linus Torvalds
88e237610b ARM: SoC fixes for -rc2
Another week, another small batch of fixes.
 
 Most of these make zynq, socfpga and sunxi platforms work a bit
 better:
 
 * Due to new requirements for regulators, DWMMC on socfpga broke past 3.17.
 * SMP spinup fix for socfpga
 * A few DT fixes for zynq
 * Another option (FIXED_REGULATOR) for sunxi is needed that used to be selected
   by other options but no longer is.
 * A couple of small DT fixes for at91
 * ...and a couple for i.MX.
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Merge tag 'armsoc-for-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

Pull ARM SoC fixes from Olof Johansson:
 "Another week, another small batch of fixes.

  Most of these make zynq, socfpga and sunxi platforms work a bit
  better:

   - due to new requirements for regulators, DWMMC on socfpga broke past
     v3.17
   - SMP spinup fix for socfpga
   - a few DT fixes for zynq
   - another option (FIXED_REGULATOR) for sunxi is needed that used to
     be selected by other options but no longer is.
   - a couple of small DT fixes for at91
   - ...and a couple for i.MX"

* tag 'armsoc-for-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: dts: imx28-evk: Let i2c0 run at 100kHz
  ARM: i.MX6: Fix "emi" clock name typo
  ARM: multi_v7_defconfig: enable CONFIG_MMC_DW_ROCKCHIP
  ARM: sunxi_defconfig: enable CONFIG_REGULATOR_FIXED_VOLTAGE
  ARM: dts: socfpga: Add a 3.3V fixed regulator node
  ARM: dts: socfpga: Fix SD card detect
  ARM: dts: socfpga: rename gpio nodes
  ARM: at91/dt: sam9263: fix PLLB frequencies
  power: reset: at91-reset: fix power down register
  MAINTAINERS: add atmel ssc driver maintainer entry
  arm: socfpga: fix fetching cpu1start_addr for SMP
  ARM: zynq: DT: trivial: Fix mc node
  ARM: zynq: DT: Add cadence watchdog node
  ARM: zynq: DT: Add missing reference for memory-controller
  ARM: zynq: DT: Add missing reference for ADC
  ARM: zynq: DT: Add missing address for L2 pl310
  ARM: zynq: DT: Remove 222 MHz OPP
  ARM: zynq: DT: Fix GEM register area size
2014-10-26 11:35:51 -07:00
Linus Torvalds
d1e14f1d63 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
 "overlayfs merge + leak fix for d_splice_alias() failure exits"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  overlayfs: embed middle into overlay_readdir_data
  overlayfs: embed root into overlay_readdir_data
  overlayfs: make ovl_cache_entry->name an array instead of pointer
  overlayfs: don't hold ->i_mutex over opening the real directory
  fix inode leaks on d_splice_alias() failure exits
  fs: limit filesystem stacking depth
  overlay: overlay filesystem documentation
  overlayfs: implement show_options
  overlayfs: add statfs support
  overlay filesystem
  shmem: support RENAME_WHITEOUT
  ext4: support RENAME_WHITEOUT
  vfs: add RENAME_WHITEOUT
  vfs: add whiteout support
  vfs: export check_sticky()
  vfs: introduce clone_private_mount()
  vfs: export __inode_permission() to modules
  vfs: export do_splice_direct() to modules
  vfs: add i_op->dentry_open()
2014-10-26 11:19:18 -07:00
Olof Johansson
efc176a8ee The i.MX fixes for 3.18:
- Revert one patch which increases I2C bus frequency on imx28-evk
  - Fix a typo on imx6q EIM clock name
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Merge tag 'imx-fixes-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux into fixes

Merge "ARM: imx: fixes for 3.18" from Shawn Guo:

The i.MX fixes for 3.18:
 - Revert one patch which increases I2C bus frequency on imx28-evk
 - Fix a typo on imx6q EIM clock name

* tag 'imx-fixes-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux:
  ARM: dts: imx28-evk: Let i2c0 run at 100kHz
  ARM: i.MX6: Fix "emi" clock name typo

Signed-off-by: Olof Johansson <olof@lixom.net>
2014-10-25 20:44:05 -07:00