Re: [PATCH] drm/virtio: Use vmalloc for command buffer allocations.

From: Gerd Hoffmann
Date: Fri Aug 30 2019 - 07:16:08 EST


Hi,

> > > - kfree(vbuf->data_buf);
> > > + kvfree(vbuf->data_buf);
> >
> > if (is_vmalloc_addr(vbuf->data_buf)) ...
> >
> > needed here I gues?
> >
>
> kvfree() handles vmalloc/kmalloc/kvmalloc internally by doing that check.

Ok.

> - videobuf_vmalloc_to_sg in drivers/media/v4l2-core/videobuf-dma-sg.c,
> assumes contiguous array of scatterlist and that the buffer being converted
> is page aligned

Well, vmalloc memory _is_ page aligned.

sg_alloc_table_from_pages() does alot of what you need, you just need a
small loop around vmalloc_to_page() create a struct page array
beforehand.

Completely different approach: use get_user_pages() and don't copy the
execbuffer at all.

cheers,
Gerd