Messages in this thread | | | Date | Tue, 5 Aug 2014 09:39:39 -0700 | From | Josh Triplett <> | Subject | Re: [PATCH] efi-bgrt: Add error handling; inform the user when ignoring the BGRT |
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On Mon, Aug 04, 2014 at 01:19:59PM +0100, Matt Fleming wrote: > On Fri, 01 Aug, at 09:11:54AM, Josh Triplett wrote: > > > > The original bug report was about an allocation failure for a fairly > > reasonable BGRT size. We can certainly prohibit absurdly huge ones (for > > instance, bigger than the maximum likely screen resolution times 4 bytes > > per pixel), but allocation failures may well occur for smaller sizes, > > and I don't think we want to spew a massive warning for that either. > > Oh, dammit, that's my bad. I misread the allocation size and thought it > was huge, but now realise it was only 6MB or so. Sorry Josh. > > I was worried that this was the first reported instance of a BGRT > claiming to be valid but with a bogusly large image size. I've never > been so happy to be wrong.
:)
> However, the fact that the allocation failed is worth investigating - > this machine appears to have GBs of ram. Perhaps we should switch to > requesting pages directly instead of relying on kmalloc()? > > I appreciate that the BGRT code isn't mission critical or anything like > that, and that failing the alloc isn't the end of the world, but if we > have code in the kernel it should really be as robust as possible. I > don't think trying to kmalloc() ~6MB can claim to be robust.
vmalloc or flex_array could potentially help here. However, I'd suggest we go ahead and merge this patch to improve the existing error handling before doing a more extensive rewrite to use one of those.
Would anything go horrifically wrong if this allocation used vmalloc? We really don't care deeply about the performance of this memory; it just needs a single copy in and a small number of copies out in the lifetime of a system.
- Josh Triplett
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