Re: [PATCH 1/5] mm, swap: Fix memory leak in setup_clusters() error path

[YoungJun Park <youngjun.park@lge.com>]

On Wed, Oct 29, 2025 at 11:41:27PM +0800, Kairui Song wrote:
> On Wed, Oct 29, 2025 at 8:44 PM Youngjun Park <youngjun.park@lge.com> wrote:
> >
> > Some error path neglects to free the allocated 'cluster_info',
> > causing a memory leak.
> >
> > Change the error jumps to the 'err_free' label to ensure proper
> > cleanup.
> >
> > Fixes: 07adc4cf1ecd ("mm, swap: implement dynamic allocation of swap table")
> > Signed-off-by: Youngjun Park <youngjun.park@lge.com>
> > ---
> >  mm/swapfile.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/swapfile.c b/mm/swapfile.c
> > index c35bb8593f50..6dc0e7a738bc 100644
> > --- a/mm/swapfile.c
> > +++ b/mm/swapfile.c
> > @@ -3339,7 +3339,7 @@ static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
> >          */
> >         err = swap_cluster_setup_bad_slot(cluster_info, 0);
> >         if (err)
> > -               goto err;
> > +               goto err_free;
> >         for (i = 0; i < swap_header->info.nr_badpages; i++) {
> >                 unsigned int page_nr = swap_header->info.badpages[i];
> >
> > @@ -3347,12 +3347,12 @@ static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
> >                         continue;
> >                 err = swap_cluster_setup_bad_slot(cluster_info, page_nr);
> >                 if (err)
> > -                       goto err;
> > +                       goto err_free;
> >         }
> >         for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) {
> >                 err = swap_cluster_setup_bad_slot(cluster_info, i);
> >                 if (err)
> > -                       goto err;
> > +                       goto err_free;
> >         }
> >
> >         INIT_LIST_HEAD(&si->free_clusters);
> > --
> > 2.34.1
> >
> >
> 
> Nice catch.

Hello Kairui.

> Maybe it's better to just move free_cluster_info under "err:"? That
> might help to avoid more issues like this. free_cluster_info checks if
> cluster_info is null already, we just need to initialize *cluster_info
> with "= NULL".

You're right - moving free_cluster_info under 'err:' is cleaner. 
I'll update the code accordingly.

Thanks!
Youngjun Park

> Just a nit pick, I'm fine either way.
> 
> Reviewed-by: Kairui Song <kasong@tencent.com>