linux-kernel - Re: [PATCH v11 09/12] vduse: take out allocations from vduse_dev_alloc

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Message-ID: <CAJaqyWePwTftOkoycpcKreAAbentzt0oEdRwNUzq0DbF46y+Xw@mail.gmail.com>
Date: Mon, 12 Jan 2026 10:26:54 +0100
From: Eugenio Perez Martin <eperezma@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: linux-kernel@...r.kernel.org, virtualization@...ts.linux.dev, 
	Maxime Coquelin <mcoqueli@...hat.com>, Laurent Vivier <lvivier@...hat.com>, Cindy Lu <lulu@...hat.com>, 
	jasowang@...hat.com, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
	Stefano Garzarella <sgarzare@...hat.com>, Yongji Xie <xieyongji@...edance.com>
Subject: Re: [PATCH v11 09/12] vduse: take out allocations from vduse_dev_alloc_coherent

On Sun, Jan 11, 2026 at 12:54 AM Michael S. Tsirkin <mst@...hat.com> wrote:
>
> On Fri, Jan 09, 2026 at 04:24:27PM +0100, Eugenio Pérez wrote:
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index 82ee476d45e0..675da1465e0e 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -923,16 +923,24 @@ static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
> >       if (!token.group)
> >               return NULL;
> >
> > +     addr = alloc_pages_exact(size, flag);
> > +     if (!addr)
> > +             return NULL;
> > +
>
> So addr has allocated pages here ...
>
>
> >       vdev = token.group->dev;
> >       domain = vdev->domain;
> >       addr = vduse_domain_alloc_coherent(domain, size,
> > -                                        (dma_addr_t *)&iova, flag);
> > +                                        (dma_addr_t *)&iova, addr);
>
> and then is overwritten here ...
>
> >       if (!addr)
> > -             return NULL;
> > +             goto err;
>
> except on error where we go to err ...
>
> >
> >       *dma_addr = (dma_addr_t)iova;
> >
> >       return addr;
> > +
> > +err:
> > +     free_pages_exact(addr, size);
>
> only to try and free NULL. will leak the original pages, will it not.
>

Right, I missed that in the conversion. I'll change the function
vduse_domain_alloc_coherent so it returns dma_addr instead of orig,
making all the code simpler. Thanks!

> > +     return NULL;
> >  }
> >
> >  static void vduse_dev_free_coherent(union virtio_map token, size_t size,
>