From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, vince@deater.net,
eranian@google.com, Arnaldo Carvalho de Melo <acme@infradead.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>
Subject: [PATCH] perf: Cleanup user's child events
Date: Fri, 15 Jan 2016 13:22:15 +0200 [thread overview]
Message-ID: <1452856935-364-1-git-send-email-alexander.shishkin@linux.intel.com> (raw)
Events are leaking in the following scenario: user creates an event for
task A, task A forks into B (producing a child event), user closes the
original event. Both original user's event and its child will remain for
as long as task B is around. In other words, we don't clean up children
when we try to release the parent.
This patch cleans up user event's children when its file descriptor is
closed.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
kernel/events/core.c | 38 +++++++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 630f53acce..867c4347ea 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3828,7 +3828,43 @@ EXPORT_SYMBOL_GPL(perf_event_release_kernel);
*/
static int perf_release(struct inode *inode, struct file *file)
{
- put_event(file->private_data);
+ struct perf_event *event = file->private_data, *child, *tmp;
+ LIST_HEAD(child_list);
+
+ /*
+ * event::child_mutex nests inside ctx::lock, so move children
+ * to a safe place first and avoid inversion
+ */
+ mutex_lock(&event->child_mutex);
+ list_splice_init(&event->child_list, &child_list);
+ mutex_unlock(&event->child_mutex);
+
+ list_for_each_entry_safe(child, tmp, &child_list, child_list) {
+ struct perf_event_context *ctx;
+
+ /*
+ * This is somewhat similar to perf_free_event(),
+ * except for these events are alive and need
+ * proper perf_remove_from_context().
+ */
+ ctx = perf_event_ctx_lock(child);
+ perf_remove_from_context(child, true);
+ perf_event_ctx_unlock(child, ctx);
+
+ list_del(&child->child_list);
+
+ /* Children will have exactly one reference */
+ free_event(child);
+
+ /*
+ * This matches the refcount bump in inherit_event();
+ * this can't be the last reference.
+ */
+ put_event(event);
+ }
+
+ /* Must be the last reference */
+ put_event(event);
return 0;
}
--
2.7.0.rc3
next reply other threads:[~2016-01-15 11:22 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 11:22 Alexander Shishkin [this message]
2016-01-15 12:54 ` [PATCH] perf: Cleanup user's child events Peter Zijlstra
2016-01-15 13:05 ` Alexander Shishkin
2016-01-15 13:09 ` Peter Zijlstra
2016-01-15 14:07 ` [PATCH] perf: Synchronously cleanup " Alexander Shishkin
2016-01-15 17:57 ` Peter Zijlstra
2016-01-18 12:07 ` Alexander Shishkin
2016-01-18 12:37 ` Alexander Shishkin
2016-01-18 14:44 ` Peter Zijlstra
2016-01-19 15:12 ` [PATCH v2] " Alexander Shishkin
2016-01-19 20:05 ` Peter Zijlstra
2016-01-19 21:58 ` Alexei Starovoitov
2016-01-20 8:32 ` Peter Zijlstra
2016-01-21 4:55 ` Alexei Starovoitov
2016-01-20 7:04 ` Alexander Shishkin
2016-01-20 8:03 ` Peter Zijlstra
2016-01-22 11:35 ` Alexander Shishkin
2016-01-22 12:12 ` Peter Zijlstra
2016-01-22 12:38 ` Peter Zijlstra
2016-01-22 19:44 ` Alexei Starovoitov
2016-01-25 11:48 ` Peter Zijlstra
2016-01-25 14:54 ` Peter Zijlstra
2016-01-25 21:04 ` Peter Zijlstra
2016-01-26 4:59 ` Alexei Starovoitov
2016-01-26 16:16 ` Peter Zijlstra
2016-01-26 17:24 ` Peter Zijlstra
2016-01-26 23:31 ` Alexei Starovoitov
2016-01-27 9:58 ` Peter Zijlstra
2016-01-27 17:52 ` Alexei Starovoitov
2016-01-29 11:28 ` [tip:perf/urgent] perf/bpf: Convert perf_event_array to use struct file tip-bot for Alexei Starovoitov
2016-01-29 20:01 ` Alexei Starovoitov
2016-01-19 20:07 ` [PATCH v2] perf: Synchronously cleanup child events Peter Zijlstra
2016-01-19 7:45 ` [PATCH] " Ingo Molnar
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