linux-stable.git/kernel/events, branch v3.16.35

perf/core: Fix perf_sched_count derailment

2016-04-30T22:05:54+00:00

commit 927a5570855836e5d5859a80ce7e91e963545e8f upstream.

The error path in perf_event_open() is such that asking for a sampling
event on a PMU that doesn't generate interrupts will end up in dropping
the perf_sched_count even though it hasn't been incremented for this
event yet.

Given a sufficient amount of these calls, we'll end up disabling
scheduler's jump label even though we'd still have active events in the
system, thereby facilitating the arrival of the infernal regions upon us.

I'm fixing this by moving account_event() inside perf_event_alloc().

Signed-off-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1456917854-29427-1-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

perf: Fix PERF_EVENT_IOC_PERIOD deadlock

2016-01-11T10:50:18+00:00

commit 642c2d671ceff40e9453203ea0c66e991e11e249 upstream.

Dmitry reported a fairly silly recursive lock deadlock for
PERF_EVENT_IOC_PERIOD, fix this by explicitly doing the inactive part of
__perf_event_period() instead of calling that function.

Reported-by: Dmitry Vyukov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Potapenko 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Eric Dumazet 
Cc: Jiri Olsa 
Cc: Kostya Serebryany 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Sasha Levin 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Fixes: c7999c6f3fed ("perf: Fix PERF_EVENT_IOC_PERIOD migration race")
Link: http://lkml.kernel.org/r/20151130115615.GJ17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

perf: Fix inherited events vs. tracepoint filters

2015-12-13T17:49:16+00:00

commit b71b437eedaed985062492565d9d421d975ae845 upstream.

Arnaldo reported that tracepoint filters seem to misbehave (ie. not
apply) on inherited events.

The fix is obvious; filters are only set on the actual (parent)
event, use the normal pattern of using this parent event for filters.
This is safe because each child event has a reference to it.

Reported-by: Arnaldo Carvalho de Melo 
Tested-by: Arnaldo Carvalho de Melo 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Adrian Hunter 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Frédéric Weisbecker 
Cc: Jiri Olsa 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Wang Nan 
Link: http://lkml.kernel.org/r/20151102095051.GN17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

perf: Fix PERF_EVENT_IOC_PERIOD migration race

2015-09-03T12:29:59+00:00

commit c7999c6f3fed9e383d3131474588f282ae6d56b9 upstream.

I ran the perf fuzzer, which triggered some WARN()s which are due to
trying to stop/restart an event on the wrong CPU.

Use the normal IPI pattern to ensure we run the code on the correct CPU.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Vince Weaver 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: bad7192b842c ("perf: Fix PERF_EVENT_IOC_PERIOD to force-reset the period")
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

perf: Fix fasync handling on inherited events

2015-08-31T13:14:08+00:00

commit fed66e2cdd4f127a43fd11b8d92a99bdd429528c upstream.

Vince reported that the fasync signal stuff doesn't work proper for
inherited events. So fix that.

Installing fasync allocates memory and sets filp->f_flags |= FASYNC,
which upon the demise of the file descriptor ensures the allocation is
freed and state is updated.

Now for perf, we can have the events stick around for a while after the
original FD is dead because of references from child events. So we
cannot copy the fasync pointer around. We can however consistently use
the parent's fasync, as that will be updated.

Reported-and-Tested-by: Vince Weaver 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho deMelo 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1434011521.1495.71.camel@twins
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

perf: Fix ring_buffer_attach() RCU sync, again

2015-07-15T09:01:28+00:00

commit 2f993cf093643b98477c421fa2b9a98dcc940323 upstream.

While looking for other users of get_state/cond_sync. I Found
ring_buffer_attach() and it looks obviously buggy?

Don't we need to ensure that we have "synchronize" _between_
list_del() and list_add() ?

IOW. Suppose that ring_buffer_attach() preempts right_after
get_state_synchronize_rcu() and gp completes before spin_lock().

In this case cond_synchronize_rcu() does nothing and we reuse
->rb_entry without waiting for gp in between?

It also moves the ->rcu_pending check under "if (rb)", to make it
more readable imo.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: dave@stgolabs.net
Cc: der.herr@hofr.at
Cc: josh@joshtriplett.org
Cc: tj@kernel.org
Fixes: b69cf53640da ("perf: Fix a race between ring_buffer_detach() and ring_buffer_attach()")
Link: http://lkml.kernel.org/r/20150530200425.GA15748@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

perf: Fix irq_work 'tail' recursion

2015-04-10T09:04:01+00:00

commit d525211f9d1be8b523ec7633f080f2116f5ea536 upstream.

Vince reported a watchdog lockup like:

	[] perf_tp_event+0xc4/0x210
	[] perf_trace_lock+0x12a/0x160
	[] lock_release+0x130/0x260
	[] _raw_spin_unlock_irqrestore+0x24/0x40
	[] do_send_sig_info+0x5d/0x80
	[] send_sigio_to_task+0x12f/0x1a0
	[] send_sigio+0xae/0x100
	[] kill_fasync+0x97/0xf0
	[] perf_event_wakeup+0xd4/0xf0
	[] perf_pending_event+0x33/0x60
	[] irq_work_run_list+0x4c/0x80
	[] irq_work_run+0x18/0x40
	[] smp_trace_irq_work_interrupt+0x3f/0xc0
	[] trace_irq_work_interrupt+0x6d/0x80

Which is caused by an irq_work generating new irq_work and therefore
not allowing forward progress.

This happens because processing the perf irq_work triggers another
perf event (tracepoint stuff) which in turn generates an irq_work ad
infinitum.

Avoid this by raising the recursion counter in the irq_work -- which
effectively disables all software events (including tracepoints) from
actually triggering again.

Reported-by: Vince Weaver 
Tested-by: Vince Weaver 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Paul Mackerras 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/20150219170311.GH21418@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

perf: Tighten (and fix) the grouping condition

2015-02-04T10:58:30+00:00

commit c3c87e770458aa004bd7ed3f29945ff436fd6511 upstream.

The fix from 9fc81d87420d ("perf: Fix events installation during
moving group") was incomplete in that it failed to recognise that
creating a group with events for different CPUs is semantically
broken -- they cannot be co-scheduled.

Furthermore, it leads to real breakage where, when we create an event
for CPU Y and then migrate it to form a group on CPU X, the code gets
confused where the counter is programmed -- triggered in practice
as well by me via the perf fuzzer.

Fix this by tightening the rules for creating groups. Only allow
grouping of counters that can be co-scheduled in the same context.
This means for the same task and/or the same cpu.

Fixes: 9fc81d87420d ("perf: Fix events installation during moving group")
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/20150123125834.090683288@infradead.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

perf: Fix events installation during moving group

2015-01-15T10:44:24+00:00

commit 9fc81d87420d0d3fd62d5e5529972c0ad9eab9cc upstream.

We allow PMU driver to change the cpu on which the event
should be installed to. This happened in patch:

  e2d37cd213dc ("perf: Allow the PMU driver to choose the CPU on which to install events")

This patch also forces all the group members to follow
the currently opened events cpu if the group happened
to be moved.

This and the change of event->cpu in perf_install_in_context()
function introduced in:

  0cda4c023132 ("perf: Introduce perf_pmu_migrate_context()")

forces group members to change their event->cpu,
if the currently-opened-event's PMU changed the cpu
and there is a group move.

Above behaviour causes problem for breakpoint events,
which uses event->cpu to touch cpu specific data for
breakpoints accounting. By changing event->cpu, some
breakpoints slots were wrongly accounted for given
cpu.

Vinces's perf fuzzer hit this issue and caused following
WARN on my setup:

   WARNING: CPU: 0 PID: 20214 at arch/x86/kernel/hw_breakpoint.c:119 arch_install_hw_breakpoint+0x142/0x150()
   Can't find any breakpoint slot
   [...]

This patch changes the group moving code to keep the event's
original cpu.

Reported-by: Vince Weaver 
Signed-off-by: Jiri Olsa 
Cc: Arnaldo Carvalho de Melo 
Cc: Frederic Weisbecker 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Vince Weaver 
Cc: Yan, Zheng 
Link: http://lkml.kernel.org/r/1418243031-20367-3-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Luis Henriques

uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME

2014-12-10T17:49:33+00:00

commit 82975bc6a6df743b9a01810fb32cb65d0ec5d60b upstream.

x86 call do_notify_resume on paranoid returns if TIF_UPROBE is set but
not on non-paranoid returns.  I suspect that this is a mistake and that
the code only works because int3 is paranoid.

Setting _TIF_NOTIFY_RESUME in the uprobe code was probably a workaround
for the x86 bug.  With that bug fixed, we can remove _TIF_NOTIFY_RESUME
from the uprobes code.

Reported-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Acked-by: Borislav Petkov 
Signed-off-by: Andy Lutomirski 
Signed-off-by: Linus Torvalds 
Signed-off-by: Luis Henriques