linux-kernel - Re: [PATCH] kernel/irq/irqdomain.c: fix memory leak with using debugfs

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Date:   Thu, 2 Feb 2023 17:51:50 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Marc Zyngier <maz@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] kernel/irq/irqdomain.c: fix memory leak with using
 debugfs_lookup()

On Thu, Feb 02, 2023 at 04:48:30PM +0000, Marc Zyngier wrote:
> On Thu, 02 Feb 2023 15:15:54 +0000,
> Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
> > 
> > When calling debugfs_lookup() the result must have dput() called on it,
> > otherwise the memory will leak over time.  To make things simpler, just
> > call debugfs_lookup_and_remove() instead which handles all of the logic
> > at once.
> > 
> > Cc: Marc Zyngier <maz@...nel.org>
> > Cc: Thomas Gleixner <tglx@...utronix.de>
> > Cc: linux-kernel@...r.kernel.org
> > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > ---
> >  kernel/irq/irqdomain.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > index 8fe1da9614ee..e2096b51c004 100644
> > --- a/kernel/irq/irqdomain.c
> > +++ b/kernel/irq/irqdomain.c
> > @@ -1915,7 +1915,7 @@ static void debugfs_add_domain_dir(struct irq_domain *d)
> >  
> >  static void debugfs_remove_domain_dir(struct irq_domain *d)
> >  {
> > -	debugfs_remove(debugfs_lookup(d->name, domain_dir));
> > +	debugfs_lookup_and_remove(d->name, domain_dir);
> >  }
> >  
> >  void __init irq_domain_debugfs_init(struct dentry *root)
> 
> Reviewed-by: Marc Zyngier <maz@...nel.org>
> 
> Maybe add a Cc stable to get this in 6.1?

Sure, I can, but how often are irq domains removed from the system under
a normal operation?

Or you can take it through your tree and add that?  I too can take it
through mine, which ever is easier for you.

thanks,

greg k-h