* [PATCH] perf: Detach group events when removing event from ctx
@ 2010-10-03 19:35 Matt Fleming
2010-10-11 10:25 ` Matt Fleming
2010-10-15 9:42 ` Peter Zijlstra
0 siblings, 2 replies; 5+ messages in thread
From: Matt Fleming @ 2010-10-03 19:35 UTC (permalink / raw)
To: linux-kernel
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Frederic Weisbecker
When removing an event from a task's list of events we need to make sure
that we also detach all group events. If we don't, then when we later
call perf_group_attach() we'll hit the WARN_ON_ONCE() like so,
[ 1200.449161] ------------[ cut here ]------------
[ 1200.449171] WARNING: at kernel/perf_event.c:313 add_event_to_ctx+0xe1/0x159()
[ 1200.449174] Hardware name: MacBook2,1
[ 1200.449176] Modules linked in: dm_mod sg sd_mod
[ 1200.449183] Pid: 7619, comm: perf Not tainted 2.6.36-rc6-tip+ #2
[ 1200.449186] Call Trace:
[ 1200.449193] [<ffffffff8103b71e>] warn_slowpath_common+0x85/0x9d
[ 1200.449197] [<ffffffff8103b750>] warn_slowpath_null+0x1a/0x1c
[ 1200.449201] [<ffffffff810a16fb>] add_event_to_ctx+0xe1/0x159
[ 1200.449206] [<ffffffff810a2f01>] perf_install_in_context+0x85/0x99
[ 1200.449210] [<ffffffff810a7811>] sys_perf_event_open+0x4da/0x633
[ 1200.449216] [<ffffffff81002b1b>] system_call_fastpath+0x16/0x1b
[ 1200.449218] ---[ end trace 9df38c30c6cacb50 ]---
Signed-off-by: Matt Fleming <matt@console-pimps.org>
---
kernel/perf_event.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index c16158c..c13d869 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -550,8 +550,11 @@ retry:
* can remove the event safely, if the call above did not
* succeed.
*/
- if (!list_empty(&event->group_entry))
+ if (!list_empty(&event->group_entry)) {
+ perf_group_detach(event);
list_del_event(event, ctx);
+ }
+
raw_spin_unlock_irq(&ctx->lock);
}
--
1.7.1
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] perf: Detach group events when removing event from ctx
2010-10-03 19:35 [PATCH] perf: Detach group events when removing event from ctx Matt Fleming
@ 2010-10-11 10:25 ` Matt Fleming
2010-10-15 9:42 ` Peter Zijlstra
1 sibling, 0 replies; 5+ messages in thread
From: Matt Fleming @ 2010-10-11 10:25 UTC (permalink / raw)
To: linux-kernel
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Frederic Weisbecker
On Sun, Oct 03, 2010 at 08:35:50PM +0100, Matt Fleming wrote:
> When removing an event from a task's list of events we need to make sure
> that we also detach all group events. If we don't, then when we later
> call perf_group_attach() we'll hit the WARN_ON_ONCE() like so,
>
> [ 1200.449161] ------------[ cut here ]------------
> [ 1200.449171] WARNING: at kernel/perf_event.c:313 add_event_to_ctx+0xe1/0x159()
> [ 1200.449174] Hardware name: MacBook2,1
> [ 1200.449176] Modules linked in: dm_mod sg sd_mod
> [ 1200.449183] Pid: 7619, comm: perf Not tainted 2.6.36-rc6-tip+ #2
> [ 1200.449186] Call Trace:
> [ 1200.449193] [<ffffffff8103b71e>] warn_slowpath_common+0x85/0x9d
> [ 1200.449197] [<ffffffff8103b750>] warn_slowpath_null+0x1a/0x1c
> [ 1200.449201] [<ffffffff810a16fb>] add_event_to_ctx+0xe1/0x159
> [ 1200.449206] [<ffffffff810a2f01>] perf_install_in_context+0x85/0x99
> [ 1200.449210] [<ffffffff810a7811>] sys_perf_event_open+0x4da/0x633
> [ 1200.449216] [<ffffffff81002b1b>] system_call_fastpath+0x16/0x1b
> [ 1200.449218] ---[ end trace 9df38c30c6cacb50 ]---
>
> Signed-off-by: Matt Fleming <matt@console-pimps.org>
> ---
> kernel/perf_event.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/perf_event.c b/kernel/perf_event.c
> index c16158c..c13d869 100644
> --- a/kernel/perf_event.c
> +++ b/kernel/perf_event.c
> @@ -550,8 +550,11 @@ retry:
> * can remove the event safely, if the call above did not
> * succeed.
> */
> - if (!list_empty(&event->group_entry))
> + if (!list_empty(&event->group_entry)) {
> + perf_group_detach(event);
> list_del_event(event, ctx);
> + }
> +
> raw_spin_unlock_irq(&ctx->lock);
> }
>
> --
> 1.7.1
Ping?
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] perf: Detach group events when removing event from ctx
2010-10-03 19:35 [PATCH] perf: Detach group events when removing event from ctx Matt Fleming
2010-10-11 10:25 ` Matt Fleming
@ 2010-10-15 9:42 ` Peter Zijlstra
2010-10-16 11:12 ` Matt Fleming
2010-10-18 19:19 ` [tip:perf/core] perf: Fix group moving tip-bot for Peter Zijlstra
1 sibling, 2 replies; 5+ messages in thread
From: Peter Zijlstra @ 2010-10-15 9:42 UTC (permalink / raw)
To: Matt Fleming
Cc: linux-kernel, Ingo Molnar, Arnaldo Carvalho de Melo, Frederic Weisbecker
On Sun, 2010-10-03 at 20:35 +0100, Matt Fleming wrote:
> When removing an event from a task's list of events we need to make sure
> that we also detach all group events. If we don't, then when we later
> call perf_group_attach() we'll hit the WARN_ON_ONCE() like so,
>
> [ 1200.449161] ------------[ cut here ]------------
> [ 1200.449171] WARNING: at kernel/perf_event.c:313 add_event_to_ctx+0xe1/0x159()
> [ 1200.449174] Hardware name: MacBook2,1
> [ 1200.449176] Modules linked in: dm_mod sg sd_mod
> [ 1200.449183] Pid: 7619, comm: perf Not tainted 2.6.36-rc6-tip+ #2
> [ 1200.449186] Call Trace:
> [ 1200.449193] [<ffffffff8103b71e>] warn_slowpath_common+0x85/0x9d
> [ 1200.449197] [<ffffffff8103b750>] warn_slowpath_null+0x1a/0x1c
> [ 1200.449201] [<ffffffff810a16fb>] add_event_to_ctx+0xe1/0x159
> [ 1200.449206] [<ffffffff810a2f01>] perf_install_in_context+0x85/0x99
> [ 1200.449210] [<ffffffff810a7811>] sys_perf_event_open+0x4da/0x633
> [ 1200.449216] [<ffffffff81002b1b>] system_call_fastpath+0x16/0x1b
> [ 1200.449218] ---[ end trace 9df38c30c6cacb50 ]---
I think its due to the new and fancy move groups around context code
from: b04243ef70 (perf: Complete software pmu grouping).
Does the below cure it?
It only detaches the group when we move it from one context to another,
the perf_install_in_context() later on will then re-assemble the group
on the other context.
---
Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -5592,6 +5592,7 @@ SYSCALL_DEFINE5(perf_event_open,
list_for_each_entry(sibling, &group_leader->sibling_list,
group_entry) {
perf_event_remove_from_context(sibling);
+ perf_group_detach(sibling);
put_ctx(gctx);
}
mutex_unlock(&gctx->mutex);
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] perf: Detach group events when removing event from ctx
2010-10-15 9:42 ` Peter Zijlstra
@ 2010-10-16 11:12 ` Matt Fleming
2010-10-18 19:19 ` [tip:perf/core] perf: Fix group moving tip-bot for Peter Zijlstra
1 sibling, 0 replies; 5+ messages in thread
From: Matt Fleming @ 2010-10-16 11:12 UTC (permalink / raw)
To: Peter Zijlstra
Cc: linux-kernel, Ingo Molnar, Arnaldo Carvalho de Melo, Frederic Weisbecker
On Fri, Oct 15, 2010 at 11:42:37AM +0200, Peter Zijlstra wrote:
> On Sun, 2010-10-03 at 20:35 +0100, Matt Fleming wrote:
> > When removing an event from a task's list of events we need to make sure
> > that we also detach all group events. If we don't, then when we later
> > call perf_group_attach() we'll hit the WARN_ON_ONCE() like so,
> >
> > [ 1200.449161] ------------[ cut here ]------------
> > [ 1200.449171] WARNING: at kernel/perf_event.c:313 add_event_to_ctx+0xe1/0x159()
> > [ 1200.449174] Hardware name: MacBook2,1
> > [ 1200.449176] Modules linked in: dm_mod sg sd_mod
> > [ 1200.449183] Pid: 7619, comm: perf Not tainted 2.6.36-rc6-tip+ #2
> > [ 1200.449186] Call Trace:
> > [ 1200.449193] [<ffffffff8103b71e>] warn_slowpath_common+0x85/0x9d
> > [ 1200.449197] [<ffffffff8103b750>] warn_slowpath_null+0x1a/0x1c
> > [ 1200.449201] [<ffffffff810a16fb>] add_event_to_ctx+0xe1/0x159
> > [ 1200.449206] [<ffffffff810a2f01>] perf_install_in_context+0x85/0x99
> > [ 1200.449210] [<ffffffff810a7811>] sys_perf_event_open+0x4da/0x633
> > [ 1200.449216] [<ffffffff81002b1b>] system_call_fastpath+0x16/0x1b
> > [ 1200.449218] ---[ end trace 9df38c30c6cacb50 ]---
>
> I think its due to the new and fancy move groups around context code
> from: b04243ef70 (perf: Complete software pmu grouping).
>
> Does the below cure it?
>
> It only detaches the group when we move it from one context to another,
> the perf_install_in_context() later on will then re-assemble the group
> on the other context.
>
> ---
> Index: linux-2.6/kernel/perf_event.c
> ===================================================================
> --- linux-2.6.orig/kernel/perf_event.c
> +++ linux-2.6/kernel/perf_event.c
> @@ -5592,6 +5592,7 @@ SYSCALL_DEFINE5(perf_event_open,
> list_for_each_entry(sibling, &group_leader->sibling_list,
> group_entry) {
> perf_event_remove_from_context(sibling);
> + perf_group_detach(sibling);
> put_ctx(gctx);
> }
> mutex_unlock(&gctx->mutex);
>
Unfortunately this still hits the WARN_ON_ONCE() :-(
^ permalink raw reply [flat|nested] 5+ messages in thread* [tip:perf/core] perf: Fix group moving
2010-10-15 9:42 ` Peter Zijlstra
2010-10-16 11:12 ` Matt Fleming
@ 2010-10-18 19:19 ` tip-bot for Peter Zijlstra
1 sibling, 0 replies; 5+ messages in thread
From: tip-bot for Peter Zijlstra @ 2010-10-18 19:19 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, a.p.zijlstra, matt, tglx, mingo
Commit-ID: 74c3337c2fc6389d3a57a622a936036b6db6b2e8
Gitweb: http://git.kernel.org/tip/74c3337c2fc6389d3a57a622a936036b6db6b2e8
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Fri, 15 Oct 2010 11:40:29 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 18 Oct 2010 19:58:51 +0200
perf: Fix group moving
Matt found we trigger the WARN_ON_ONCE() in perf_group_attach() when we take
the move_group path in perf_event_open().
Since we cannot de-construct the group (we rely on it to move the events), we
have to simply ignore the double attach. The group state is context invariant
and doesn't need changing.
Reported-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1287135757.29097.1368.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/perf_event.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 99b9700..346dc0e 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -315,7 +315,12 @@ static void perf_group_attach(struct perf_event *event)
{
struct perf_event *group_leader = event->group_leader;
- WARN_ON_ONCE(event->attach_state & PERF_ATTACH_GROUP);
+ /*
+ * We can have double attach due to group movement in perf_event_open.
+ */
+ if (event->attach_state & PERF_ATTACH_GROUP)
+ return;
+
event->attach_state |= PERF_ATTACH_GROUP;
if (group_leader == event)
^ permalink raw reply [flat|nested] 5+ messages in thread
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2010-10-03 19:35 [PATCH] perf: Detach group events when removing event from ctx Matt Fleming
2010-10-11 10:25 ` Matt Fleming
2010-10-15 9:42 ` Peter Zijlstra
2010-10-16 11:12 ` Matt Fleming
2010-10-18 19:19 ` [tip:perf/core] perf: Fix group moving tip-bot for Peter Zijlstra
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