[PATCH 1/4] zswap bugfix: memory leaks when re-swapon

[PATCH 1/4] zswap bugfix: memory leaks when re-swapon

[Weijie Yang]

zswap_tree is not freed when swapoff, and it got re-kzalloc in swapon,
memory leak occurs.
Add check statement in zswap_frontswap_init so that zswap_tree is
inited only once.

---
 mm/zswap.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index deda2b6..1cf1c07 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -826,6 +826,11 @@ static void zswap_frontswap_init(unsigned type)
 {
 	struct zswap_tree *tree;

+	if (zswap_trees[type]) {
+		BUG_ON(zswap_trees[type]->rbroot != RB_ROOT);  /* invalidate_area set it */
+		return;
+	}
+
 	tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL);
 	if (!tree)
 		goto err;
-- 
1.7.0.4

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Re: [PATCH 1/4] zswap bugfix: memory leaks when re-swapon

[Seth Jennings]

On Fri, Aug 23, 2013 at 07:03:37PM +0800, Weijie Yang wrote:
> zswap_tree is not freed when swapoff, and it got re-kzalloc in swapon,
> memory leak occurs.
> Add check statement in zswap_frontswap_init so that zswap_tree is
> inited only once.
> 
> ---
>  mm/zswap.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/mm/zswap.c b/mm/zswap.c
> index deda2b6..1cf1c07 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -826,6 +826,11 @@ static void zswap_frontswap_init(unsigned type)
>  {
>  	struct zswap_tree *tree;
> 
> +	if (zswap_trees[type]) {
> +		BUG_ON(zswap_trees[type]->rbroot != RB_ROOT);  /* invalidate_area set it */

Lets leave this BUG_ON() out.  If we want to make sure that the rbtree has
been properly emptied out, we should do it in
zswap_frontswap_invalidate_area() after the while loop and make it a
WARN_ON() since the problem is not fatal.

Seth

> +		return;
> +	}
> +
>  	tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL);
>  	if (!tree)
>  		goto err;
> -- 
> 1.7.0.4
> 

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Re: [PATCH 1/4] zswap bugfix: memory leaks when re-swapon

[Weijie Yang]

2013/8/23 Seth Jennings <sjenning@linux.vnet.ibm.com>:
> On Fri, Aug 23, 2013 at 07:03:37PM +0800, Weijie Yang wrote:
>> zswap_tree is not freed when swapoff, and it got re-kzalloc in swapon,
>> memory leak occurs.
>> Add check statement in zswap_frontswap_init so that zswap_tree is
>> inited only once.
>>
>> ---
>>  mm/zswap.c |    5 +++++
>>  1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/zswap.c b/mm/zswap.c
>> index deda2b6..1cf1c07 100644
>> --- a/mm/zswap.c
>> +++ b/mm/zswap.c
>> @@ -826,6 +826,11 @@ static void zswap_frontswap_init(unsigned type)
>>  {
>>       struct zswap_tree *tree;
>>
>> +     if (zswap_trees[type]) {
>> +             BUG_ON(zswap_trees[type]->rbroot != RB_ROOT);  /* invalidate_area set it */
>
> Lets leave this BUG_ON() out.  If we want to make sure that the rbtree has
> been properly emptied out, we should do it in
> zswap_frontswap_invalidate_area() after the while loop and make it a
> WARN_ON() since the problem is not fatal.
>
> Seth
>

ok.

>> +             return;
>> +     }
>> +
>>       tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL);
>>       if (!tree)
>>               goto err;
>> --
>> 1.7.0.4
>>
>

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