This is a note to let you know that I've just added the patch titled
perf: Fix hotplug splat
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-fix-hotplug-splat.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e3703f8cdfcf39c25c4338c3ad8e68891cca3731 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Mon, 24 Feb 2014 12:06:12 +0100
Subject: perf: Fix hotplug splat
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit e3703f8cdfcf39c25c4338c3ad8e68891cca3731 upstream.
Drew Richardson reported that he could make the kernel go *boom* when hotplugging
while having perf events active.
It turned out that when you have a group event, the code in
__perf_event_exit_context() fails to remove the group siblings from
the context.
We then proceed with destroying and freeing the event, and when you
re-plug the CPU and try and add another event to that CPU, things go
*boom* because you've still got dead entries there.
Reported-by: Drew Richardson <drew.richardson@xxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Link: http://lkml.kernel.org/n/tip-k6v5wundvusvcseqj1si0oz0@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/events/core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7149,14 +7149,14 @@ static void perf_pmu_rotate_stop(struct
static void __perf_event_exit_context(void *__info)
{
struct perf_event_context *ctx = __info;
- struct perf_event *event, *tmp;
+ struct perf_event *event;
perf_pmu_rotate_stop(ctx->pmu);
- list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
- __perf_remove_from_context(event);
- list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
+ rcu_read_lock();
+ list_for_each_entry_rcu(event, &ctx->event_list, event_entry)
__perf_remove_from_context(event);
+ rcu_read_unlock();
}
static void perf_event_exit_cpu_context(int cpu)
@@ -7180,11 +7180,11 @@ static void perf_event_exit_cpu(int cpu)
{
struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+ perf_event_exit_cpu_context(cpu);
+
mutex_lock(&swhash->hlist_mutex);
swevent_hlist_release(swhash);
mutex_unlock(&swhash->hlist_mutex);
-
- perf_event_exit_cpu_context(cpu);
}
#else
static inline void perf_event_exit_cpu(int cpu) { }
Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are
queue-3.4/perf-fix-hotplug-splat.patch
queue-3.4/perf-x86-fix-event-scheduling.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html