6.12-stable review patch. If anyone has any objections, please let me know.
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From: Matthew Auld matthew.auld@intel.com
commit 25583ad42d091819157832e894179200ba8b54ee upstream.
The is_vram() is checking the current placement, however if we consider exported VRAM with dynamic dma-buf, it looks possible for the xe driver to async evict the memory, notifying the importer, however importer does not have to call unmap_attachment() immediately, but rather just as "soon as possible", like when the dma-resv idles. Following from this we would then pipeline the move, attaching the fence to the manager, and then update the current placement. But when the unmap_attachment() runs at some later point we might see that is_vram() is now false, and take the complete wrong path when dma-unmapping the sg, leading to explosions.
To fix this check if the sgl was mapping a struct page.
v2: - The attachment can be mapped multiple times it seems, so we can't really rely on encoding something in the attachment->priv. Instead see if the page_link has an encoded struct page. For vram we expect this to be NULL.
Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4563 Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Thomas Hellström thomas.hellstrom@linux.intel.com Cc: Matthew Brost matthew.brost@intel.com Cc: stable@vger.kernel.org # v6.8+ Acked-by: Christian König christian.koenig@amd.com Link: https://lore.kernel.org/r/20250410162716.159403-2-matthew.auld@intel.com (cherry picked from commit d755887f8e5a2a18e15e6632a5193e5feea18499) Signed-off-by: Lucas De Marchi lucas.demarchi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/xe/xe_dma_buf.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
--- a/drivers/gpu/drm/xe/xe_dma_buf.c +++ b/drivers/gpu/drm/xe/xe_dma_buf.c @@ -145,10 +145,7 @@ static void xe_dma_buf_unmap(struct dma_ struct sg_table *sgt, enum dma_data_direction dir) { - struct dma_buf *dma_buf = attach->dmabuf; - struct xe_bo *bo = gem_to_xe_bo(dma_buf->priv); - - if (!xe_bo_is_vram(bo)) { + if (sg_page(sgt->sgl)) { dma_unmap_sgtable(attach->dev, sgt, dir, 0); sg_free_table(sgt); kfree(sgt);