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From:   Ralph Campbell <rcampbell@nvidia.com>
To:     <dri-devel@lists.freedesktop.org>, <linux-rdma@vger.kernel.org>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <nouveau@lists.freedesktop.org>
CC:     Jerome Glisse <jglisse@redhat.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Christoph Hellwig <hch@lst.de>,
        Jason Gunthorpe <jgg@mellanox.com>,
        "Andrew Morton" <akpm@linux-foundation.org>,
        Ben Skeggs <bskeggs@redhat.com>,
        "Ralph Campbell" <rcampbell@nvidia.com>
Subject: [PATCH v3 1/4] nouveau/hmm: fix vma range check for migration
Date:   Tue, 3 Mar 2020 16:13:36 -0800
Message-ID: <20200304001339.8248-2-rcampbell@nvidia.com>
In-Reply-To: <20200304001339.8248-1-rcampbell@nvidia.com>
References: <20200304001339.8248-1-rcampbell@nvidia.com>
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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/nouvea=
u/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;
=20
+		addr =3D max(addr, vma->vm_start);
 		next =3D min(vma->vm_end, end);
 		/* This is a best effort so we ignore errors */
 		nouveau_dmem_migrate_vma(cli->drm, vma, addr, next);
--=20
2.20.1