Messages in this thread | | | Date | Fri, 8 Feb 2008 09:48:58 +0200 | From | "Pekka Enberg" <> | Subject | Re: [PATCH 1/2] kmemcheck v3 |
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Hi Christoph,
On Thu, 7 Feb 2008, Vegard Nossum wrote: > > - DMA can be a problem since there's generally no way for kmemcheck to > > determine when/if a chunk of memory is used for DMA. Ideally, DMA should be > > allocated with untracked caches, but this requires annotation of the > > drivers in question.
On Feb 8, 2008 9:10 AM, Christoph Lameter <clameter@sgi.com> wrote: > There is a fundamental misunderstanding here: GFP_DMA allocations have > nothing to do with DMA. Rather GFP_DMA means allocate memory in a special > range of physical memory that is required by legacy devices that cannot > use the high address bits for one or the other reason. Any regular > memory can be used for DMA.
No there isn't and we've been over this with Vegard many times :-). Christoph, can you actually see this in the patch? There shouldn't be any __GFP_DMA confusion there. What we have is per-object __GFP_NOTRACK which can be used to suppress false positives for DMA-filled objects and SLAB_NOTRACK for whole _caches_ that contains objects which we must not take page faults at all.
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