On 03/08/2012 06:35 PM, Kirill A. Shutemov wrote:
On Thu, Mar 08, 2012 at 10:11:32AM +0800, Sha Zhengju wrote:
On 03/08/2012 07:08 AM, Kirill A. Shutemov wrote:
On Tue, Mar 06, 2012 at 08:13:24PM +0800, Sha Zhengju wrote:
From: Sha Zhengju<handai.szj@xxxxxxxxxx>
When the last event is unregistered, there is no need to keep the spare
array anymore. So free it to avoid memory leak.
It's not a leak. It will be freed on next event register.
Yeah, I noticed that. But what if it is just the last one and no more
event registering ?
See my question below. ;)
Yeah, we don't have to keep spare if primary is empty. But is it worth to
make code more complicated to save few bytes of memory?
If we unregister the last event and *don't* register a new event anymore,
the primary is freed but the spare is still kept which has no chance to
free.
IMHO, it's obvious not a problem of saving bytes but *memory leak*.
Signed-off-by: Sha Zhengju<handai.szj@xxxxxxxxxx>
---
mm/memcontrol.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 22d94f5..3c09a84 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4412,6 +4412,12 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
swap_buffers:
/* Swap primary and spare array */
thresholds->spare = thresholds->primary;
+ /* If all events are unregistered, free the spare array */
+ if (!new) {
+ kfree(thresholds->spare);
+ thresholds->spare = NULL;
+ }
+
rcu_assign_pointer(thresholds->primary, new);
/* To be sure that nobody uses thresholds */
--
1.7.4.1
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