linux-toradex.git/kernel, branch v3.14.7

sched: Fix sched_policy < 0 comparison

2014-06-11T18:54:11+00:00

commit b14ed2c273f8ab872ae4e6735fe5ab09cb14b8c3 upstream.

attr.sched_policy is u32, therefore a comparison against < 0 is never true.
Fix this by casting sched_policy to int.

This issue was reported by coverity CID 1219934.

Fixes: dbdb22754fde ("sched: Disallow sched_attr::sched_policy < 0")
Signed-off-by: Richard Weinberger 
Signed-off-by: Peter Zijlstra 
Cc: Michael Kerrisk 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/1401741514-7045-1-git-send-email-richard@nod.at
Signed-off-by: Ingo Molnar 
Cc: Dave Jones 
Signed-off-by: Greg Kroah-Hartman

sched/dl: Fix race in dl_task_timer()

2014-06-11T18:54:11+00:00

commit 0f397f2c90ce68821ee864c2c53baafe78de765d upstream.

Throttled task is still on rq, and it may be moved to other cpu
if user is playing with sched_setaffinity(). Therefore, unlocked
task_rq() access makes the race.

Juri Lelli reports he got this race when dl_bandwidth_enabled()
was not set.

Other thing, pointed by Peter Zijlstra:

   "Now I suppose the problem can still actually happen when
    you change the root domain and trigger a effective affinity
    change that way".

To fix that we do the same as made in __task_rq_lock(). We do not
use __task_rq_lock() itself, because it has a useful lockdep check,
which is not correct in case of dl_task_timer(). We do not need
pi_lock locked here. This case is an exception (PeterZ):

   "The only reason we don't strictly need ->pi_lock now is because
    we're guaranteed to have p->state == TASK_RUNNING here and are
    thus free of ttwu races".

Signed-off-by: Kirill Tkhai 
Signed-off-by: Peter Zijlstra 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/3056991400578422@web14g.yandex.ru
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched: Fix hotplug vs. set_cpus_allowed_ptr()

2014-06-11T18:54:11+00:00

commit 6acbfb96976fc3350e30d964acb1dbbdf876d55e upstream.

Lai found that:

  WARNING: CPU: 1 PID: 13 at arch/x86/kernel/smp.c:124 native_smp_send_reschedule+0x2d/0x4b()
  ...
  migration_cpu_stop+0x1d/0x22

was caused by set_cpus_allowed_ptr() assuming that cpu_active_mask is
always a sub-set of cpu_online_mask.

This isn't true since 5fbd036b552f ("sched: Cleanup cpu_active madness").

So set active and online at the same time to avoid this particular
problem.

Fixes: 5fbd036b552f ("sched: Cleanup cpu_active madness")
Signed-off-by: Lai Jiangshan 
Signed-off-by: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Gautham R. Shenoy 
Cc: Linus Torvalds 
Cc: Michael wang 
Cc: Paul Gortmaker 
Cc: Rafael J. Wysocki 
Cc: Srivatsa S. Bhat 
Cc: Toshi Kani 
Link: http://lkml.kernel.org/r/53758B12.8060609@cn.fujitsu.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched/deadline: Restrict user params max value to 2^63 ns

2014-06-11T18:54:10+00:00

commit b0827819b0da4acfbc1df1e05edcf50efd07cbd1 upstream.

Michael Kerrisk noticed that creating SCHED_DEADLINE reservations
with certain parameters (e.g, a runtime of something near 2^64 ns)
can cause a system freeze for some amount of time.

The problem is that in the interface we have

 u64 sched_runtime;

while internally we need to have a signed runtime (to cope with
budget overruns)

 s64 runtime;

At the time we setup a new dl_entity we copy the first value in
the second. The cast turns out with negative values when
sched_runtime is too big, and this causes the scheduler to go crazy
right from the start.

Moreover, considering how we deal with deadlines wraparound

 (s64)(a - b) < 0

we also have to restrict acceptable values for sched_{deadline,period}.

This patch fixes the thing checking that user parameters are always
below 2^63 ns (still large enough for everyone).

It also rewrites other conditions that we check, since in
__checkparam_dl we don't have to deal with deadline wraparounds
and what we have now erroneously fails when the difference between
values is too big.

Reported-by: Michael Kerrisk 
Suggested-by: Peter Zijlstra 
Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra 
Cc: Dario Faggioli
Cc: Dave Jones 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/20140513141131.20d944f81633ee937f256385@gmail.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched/deadline: Change sched_getparam() behaviour vs SCHED_DEADLINE

2014-06-11T18:54:10+00:00

commit ce5f7f8200ca2504f6f290044393d73ca314965a upstream.

The way we read POSIX one should only call sched_getparam() when
sched_getscheduler() returns either SCHED_FIFO or SCHED_RR.

Given that we currently return sched_param::sched_priority=0 for all
others, extend the same behaviour to SCHED_DEADLINE.

Requested-by: Michael Kerrisk 
Signed-off-by: Peter Zijlstra 
Acked-by: Michael Kerrisk 
Cc: Dario Faggioli 
Cc: linux-man 
Cc: "Michael Kerrisk (man-pages)" 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/20140512205034.GH13467@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched: Make sched_setattr() correctly return -EFBIG

2014-06-11T18:54:10+00:00

commit 143cf23df25b7082cd706c3c53188e741e7881c3 upstream.

The documented[1] behavior of sched_attr() in the proposed man page text is:

    sched_attr::size must be set to the size of the structure, as in
    sizeof(struct sched_attr), if the provided structure is smaller
    than the kernel structure, any additional fields are assumed
    '0'. If the provided structure is larger than the kernel structure,
    the kernel verifies all additional fields are '0' if not the
    syscall will fail with -E2BIG.

As currently implemented, sched_copy_attr() returns -EFBIG for
for this case, but the logic in sys_sched_setattr() converts that
error to -EFAULT. This patch fixes the behavior.

[1] http://thread.gmane.org/gmane.linux.kernel/1615615/focus=1697760

Signed-off-by: Michael Kerrisk 
Signed-off-by: Peter Zijlstra 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/536CEC17.9070903@gmail.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched: Disallow sched_attr::sched_policy < 0

2014-06-11T18:54:10+00:00

commit dbdb22754fde671dc93d2fae06f8be113d47f2fb upstream.

The scheduler uses policy=-1 to preserve the current policy state to
implement sys_sched_setparam(), this got exposed to userspace by
accident through sys_sched_setattr(), cure this.

Reported-by: Michael Kerrisk 
Signed-off-by: Peter Zijlstra 
Acked-by: Michael Kerrisk 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/20140509085311.GJ30445@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf: Fix race in removing an event

2014-06-11T18:54:08+00:00

commit 46ce0fe97a6be7532ce6126bb26ce89fed81528c upstream.

When removing a (sibling) event we do:

	raw_spin_lock_irq(&ctx->lock);
	perf_group_detach(event);
	raw_spin_unlock_irq(&ctx->lock);

	

	perf_remove_from_context(event);
		raw_spin_lock_irq(&ctx->lock);
		...
		raw_spin_unlock_irq(&ctx->lock);

Now, assuming the event is a sibling, it will be 'unreachable' for
things like ctx_sched_out() because that iterates the
groups->siblings, and we just unhooked the sibling.

So, if during  we get ctx_sched_out(), it will miss the event
and not call event_sched_out() on it, leaving it programmed on the
PMU.

The subsequent perf_remove_from_context() call will find the ctx is
inactive and only call list_del_event() to remove the event from all
other lists.

Hereafter we can proceed to free the event; while still programmed!

Close this hole by moving perf_group_detach() inside the same
ctx->lock region(s) perf_remove_from_context() has.

The condition on inherited events only in __perf_event_exit_task() is
likely complete crap because non-inherited events are part of groups
too and we're tearing down just the same. But leave that for another
patch.

Most-likely-Fixes: e03a9a55b4e ("perf: Change close() semantics for group events")
Reported-by: Vince Weaver 
Tested-by: Vince Weaver 
Much-staring-at-traces-by: Vince Weaver 
Much-staring-at-traces-by: Thomas Gleixner 
Cc: Arnaldo Carvalho de Melo 
Cc: Linus Torvalds 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20140505093124.GN17778@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf: Limit perf_event_attr::sample_period to 63 bits

2014-06-11T18:54:08+00:00

commit 0819b2e30ccb93edf04876237b6205eef84ec8d2 upstream.

Vince reported that using a large sample_period (one with bit 63 set)
results in wreckage since while the sample_period is fundamentally
unsigned (negative periods don't make sense) the way we implement
things very much rely on signed logic.

So limit sample_period to 63 bits to avoid tripping over this.

Reported-by: Vince Weaver 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-p25fhunibl4y3qi0zuqmyf4b@git.kernel.org
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

perf: Prevent false warning in perf_swevent_add

2014-06-11T18:54:08+00:00

commit 39af6b1678afa5880dda7e375cf3f9d395087f6d upstream.

The perf cpu offline callback takes down all cpu context
events and releases swhash->swevent_hlist.

This could race with task context software event being just
scheduled on this cpu via perf_swevent_add while cpu hotplug
code already cleaned up event's data.

The race happens in the gap between the cpu notifier code
and the cpu being actually taken down. Note that only cpu
ctx events are terminated in the perf cpu hotplug code.

It's easily reproduced with:
  $ perf record -e faults perf bench sched pipe

while putting one of the cpus offline:
  # echo 0 > /sys/devices/system/cpu/cpu1/online

Console emits following warning:
  WARNING: CPU: 1 PID: 2845 at kernel/events/core.c:5672 perf_swevent_add+0x18d/0x1a0()
  Modules linked in:
  CPU: 1 PID: 2845 Comm: sched-pipe Tainted: G        W    3.14.0+ #256
  Hardware name: Intel Corporation Montevina platform/To be filled by O.E.M., BIOS AMVACRB1.86C.0066.B00.0805070703 05/07/2008
   0000000000000009 ffff880077233ab8 ffffffff81665a23 0000000000200005
   0000000000000000 ffff880077233af8 ffffffff8104732c 0000000000000046
   ffff88007467c800 0000000000000002 ffff88007a9cf2a0 0000000000000001
  Call Trace:
   [] dump_stack+0x4f/0x7c
   [] warn_slowpath_common+0x8c/0xc0
   [] warn_slowpath_null+0x1a/0x20
   [] perf_swevent_add+0x18d/0x1a0
   [] event_sched_in.isra.75+0x9e/0x1f0
   [] group_sched_in+0x6a/0x1f0
   [] ? sched_clock_local+0x25/0xa0
   [] ctx_sched_in+0x1f6/0x450
   [] perf_event_sched_in+0x6b/0xa0
   [] perf_event_context_sched_in+0x7b/0xc0
   [] __perf_event_task_sched_in+0x43e/0x460
   [] ? put_lock_stats.isra.18+0xe/0x30
   [] finish_task_switch+0xb8/0x100
   [] __schedule+0x30e/0xad0
   [] ? pipe_read+0x3e2/0x560
   [] ? preempt_schedule_irq+0x3e/0x70
   [] ? preempt_schedule_irq+0x3e/0x70
   [] preempt_schedule_irq+0x44/0x70
   [] retint_kernel+0x20/0x30
   [] ? lockdep_sys_exit+0x1a/0x90
   [] lockdep_sys_exit_thunk+0x35/0x67
   [] ? sysret_check+0x5/0x56

Fixing this by tracking the cpu hotplug state and displaying
the WARN only if current cpu is initialized properly.

Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Reported-by: Fengguang Wu 
Signed-off-by: Jiri Olsa 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1396861448-10097-1-git-send-email-jolsa@redhat.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman