[openib-general] Re: [git patch review 2/2] IB: Don't doublefree pages from scatterlist

[Hugh Dickins]

On Sat, 4 Feb 2006, Roland Dreier wrote:

> On some architectures, mapping the scatterlist may coalesce entries:
> if that coalesced list is then used for freeing the pages afterwards,
> there's a danger that pages may be doubly freed (and others leaked).
> 
> Fix Infiniband's __ib_umem_release by freeing from a separate array
> beyond the scatterlist: IB_UMEM_MAX_PAGE_CHUNK lowered to fit one page.

It's now looking like this change won't be needed after all: Andi has
just posted a patch in the "ipr" thread which should stop x86_64 from
interfering with the scatterlist *page,offset,length fields, so what
IB and others were doing should then work safely (current thinking is
that x86_64 is the only architecture which coalesced in that way).

Hugh