[PATCH] mm/damon/reclaim: fix potential memory leak in damon_reclaim_init()

[PATCH] mm/damon/reclaim: fix potential memory leak in damon_reclaim_init()

[Jianglei Nie]

damon_reclaim_init() allocates a memory chunk for ctx with
damon_new_ctx(). When damon_select_ops() fails, ctx is not released, which
will lead to a memory leak.

We should release the ctx with damon_destroy_ctx() when damon_select_ops()
fails to fix the memory leak.

Fixes: 4d69c3457821 ("mm/damon/reclaim: use damon_select_ops() instead of damon_{v,p}a_set_operations()")
Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
 mm/damon/reclaim.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 4b07c29effe9..0b3c7396cb90 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -441,8 +441,10 @@ static int __init damon_reclaim_init(void)
 	if (!ctx)
 		return -ENOMEM;
 
-	if (damon_select_ops(ctx, DAMON_OPS_PADDR))
+	if (damon_select_ops(ctx, DAMON_OPS_PADDR)) {
+		damon_destroy_ctx(ctx);
 		return -EINVAL;
+	}
 
 	ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
 	ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
-- 
2.25.1

Re: [PATCH] mm/damon/reclaim: fix potential memory leak in damon_reclaim_init()

[Greg KH]

On Sun, Jul 24, 2022 at 02:52:24PM +0800, Jianglei Nie wrote:
> damon_reclaim_init() allocates a memory chunk for ctx with
> damon_new_ctx(). When damon_select_ops() fails, ctx is not released, which
> will lead to a memory leak.
> 
> We should release the ctx with damon_destroy_ctx() when damon_select_ops()
> fails to fix the memory leak.
> 
> Fixes: 4d69c3457821 ("mm/damon/reclaim: use damon_select_ops() instead of damon_{v,p}a_set_operations()")
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
>  mm/damon/reclaim.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> index 4b07c29effe9..0b3c7396cb90 100644
> --- a/mm/damon/reclaim.c
> +++ b/mm/damon/reclaim.c
> @@ -441,8 +441,10 @@ static int __init damon_reclaim_init(void)
>  	if (!ctx)
>  		return -ENOMEM;
>  
> -	if (damon_select_ops(ctx, DAMON_OPS_PADDR))
> +	if (damon_select_ops(ctx, DAMON_OPS_PADDR)) {
> +		damon_destroy_ctx(ctx);
>  		return -EINVAL;
> +	}
>  
>  	ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
>  	ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
> -- 
> 2.25.1
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

Re: [PATCH] mm/damon/reclaim: fix potential memory leak in damon_reclaim_init()

[SeongJae Park]

Hi Jianglei and Greg,

On Sun, 24 Jul 2022 09:18:52 +0200 Greg KH <gregkh@linuxfoundation.org> wrote:

> On Sun, Jul 24, 2022 at 02:52:24PM +0800, Jianglei Nie wrote:
> > damon_reclaim_init() allocates a memory chunk for ctx with
> > damon_new_ctx(). When damon_select_ops() fails, ctx is not released, which
> > will lead to a memory leak.
> > 
> > We should release the ctx with damon_destroy_ctx() when damon_select_ops()
> > fails to fix the memory leak.
> > 
> > Fixes: 4d69c3457821 ("mm/damon/reclaim: use damon_select_ops() instead of damon_{v,p}a_set_operations()")
> > Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> > ---
> >  mm/damon/reclaim.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> > index 4b07c29effe9..0b3c7396cb90 100644
> > --- a/mm/damon/reclaim.c
> > +++ b/mm/damon/reclaim.c
> > @@ -441,8 +441,10 @@ static int __init damon_reclaim_init(void)
> >  	if (!ctx)
> >  		return -ENOMEM;
> >  
> > -	if (damon_select_ops(ctx, DAMON_OPS_PADDR))
> > +	if (damon_select_ops(ctx, DAMON_OPS_PADDR)) {
> > +		damon_destroy_ctx(ctx);
> >  		return -EINVAL;
> > +	}
> >  
> >  	ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
> >  	ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
> > -- 
> > 2.25.1
> > 
> 
> <formletter>
> 
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read:
>     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.
> 
> </formletter>

Thank you for the notice, Greg.  Jianglei, please read that great document.

And Andrew already added the 'Fixes:' and 'Cc: stable@' tags in the patch when
he added[1] it in the mm tree.  Hence I think this would be merged in the
appropriate stable series once it gets merged in the mainline.

[1] https://lore.kernel.org/mm-commits/20220717004946.7AD93C34114@smtp.kernel.org/


Thanks,
SJ

Re: [PATCH] mm/damon/reclaim: fix potential memory leak in damon_reclaim_init()

[SeongJae Park]

Hello Jianglei,

On Thu, 14 Jul 2022 14:37:46 +0800 Jianglei Nie <niejianglei2021@163.com> wrote:

> damon_reclaim_init() allocates a memory chunk for ctx with
> damon_new_ctx(). When damon_select_ops() fails, ctx is not released, which
> will lead to a memory leak.
> 
> We should release the ctx with damon_destroy_ctx() when damon_select_ops()
> fails to fix the memory leak.

Thank you for this patch!

I think below tags would be better to be added.

Fixes: 4d69c3457821 ("mm/damon/reclaim: use damon_select_ops() instead of damon_{v,p}a_set_operations()")
Cc: <stable@vger.kernel.org> # 5.18.x

> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

> ---
>  mm/damon/reclaim.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> index 4b07c29effe9..0b3c7396cb90 100644
> --- a/mm/damon/reclaim.c
> +++ b/mm/damon/reclaim.c
> @@ -441,8 +441,10 @@ static int __init damon_reclaim_init(void)
>  	if (!ctx)
>  		return -ENOMEM;
>  
> -	if (damon_select_ops(ctx, DAMON_OPS_PADDR))
> +	if (damon_select_ops(ctx, DAMON_OPS_PADDR)) {
> +		damon_destroy_ctx(ctx);
>  		return -EINVAL;
> +	}
>  
>  	ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
>  	ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
> -- 
> 2.25.1

Re: [PATCH] mm/damon/reclaim: fix potential memory leak in damon_reclaim_init()

[SeongJae Park]

Hello Jianglei,

On Thu, 14 Jul 2022 16:44:27 +0000 SeongJae Park <sj@kernel.org> wrote:

> Hello Jianglei,
> 
> On Thu, 14 Jul 2022 14:37:46 +0800 Jianglei Nie <niejianglei2021@163.com> wrote:
> 
> > damon_reclaim_init() allocates a memory chunk for ctx with
> > damon_new_ctx(). When damon_select_ops() fails, ctx is not released, which
> > will lead to a memory leak.

I realized this issue is also in DAMON_LRU_SORT, so posted a patch:
https://lore.kernel.org/damon/20220714170458.49727-1-sj@kernel.org/

I mistakenly forgot CC-ing you, so letting you know here.


Thanks,
SJ