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References: <20200304001339.8248-1-rcampbell@nvidia.com> <20200304001339.8248-2-rcampbell@nvidia.com>
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From:   Ben Skeggs <skeggsb@gmail.com>
Date:   Thu, 12 Mar 2020 17:55:39 +1000
Message-ID: <CACAvsv4+od30K-FAr5Fet7kOz1APRDTXmHRc3fN4eiCVDhY02w@mail.gmail.com>
Subject: Re: [Nouveau] [PATCH v3 1/4] nouveau/hmm: fix vma range check for migration
To:     Ralph Campbell <rcampbell@nvidia.com>
Cc:     ML dri-devel <dri-devel@lists.freedesktop.org>,
        linux-rdma@vger.kernel.org, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>,
        ML nouveau <nouveau@lists.freedesktop.org>,
        Jason Gunthorpe <jgg@mellanox.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Hellwig <hch@lst.de>
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Sender: linux-kernel-owner@vger.kernel.org
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I've taken all 4 patches in my tree.

Thanks Ralph,
Ben.

On Wed, 4 Mar 2020 at 10:14, Ralph Campbell <rcampbell@nvidia.com> wrote:
>
> find_vma_intersection(mm, start, end) only guarantees that end is greater
> than or equal to vma->vm_start but doesn't guarantee that start is
> greater than or equal to vma->vm_start. The calculation for the
> intersecting range in nouveau_svmm_bind() isn't accounting for this and
> can call migrate_vma_setup() with a starting address less than
> vma->vm_start. This results in migrate_vma_setup() returning -EINVAL for
> the range instead of nouveau skipping that part of the range and migrating
> the rest.
>
> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_svm.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
> index df9bf1fd1bc0..169320409286 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -179,6 +179,7 @@ nouveau_svmm_bind(struct drm_device *dev, void *data,
>                 if (!vma)
>                         break;
>
> +               addr = max(addr, vma->vm_start);
>                 next = min(vma->vm_end, end);
>                 /* This is a best effort so we ignore errors */
>                 nouveau_dmem_migrate_vma(cli->drm, vma, addr, next);
> --
> 2.20.1
>
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