Re: [PATCH] jffs2 summary allocation

David Brownell
2008-04-04T23:09:45Z

On Friday 04 April 2008, Andrew Morton wrote:

> I'm assuming from the trace that the arm code tried to put that memory
> under DMA (or at least, passed it into part of the DMA management code to
> get the various caches sorted out) and that the arm DMA support code
> doesn't like being given vmalloced memory.

Actually, Documentation/DMA-Mapping.txt has a section right up
front called "What memory is DMA'able?" ... which despite its
ungrammatical title, says clearly:

... This means specifically that you may _not_ use the
memory/addresses returned from vmalloc() for DMA. ...

So I'm rather surprised to see *ANY* kernel code trying to do
that. That rule has been in effect for many, many years now.

- Dave