Re: DMA memory, split_page, BUG_ON(PageCompound()), sound

From: Nick Piggin
Date: Mon Jul 10 2006 - 17:51:20 EST


Russell King wrote:
On Mon, Jul 10, 2006 at 04:59:48PM +1000, Nick Piggin wrote:

I guess you could do it a number of ways. Maybe having GFP_USERMAP
set __GFP_USERMAP|__GFP_COMP, and the arm dma memory allocator can
strip the __GFP_COMP.

If you get an explicit __GFP_COMP passed down, the allocator doesn't
know whether that was because they want a user mappable area, or
really want a compound page (in which case, stripping __GFP_COMP is
the wrong thing to do).


So I'll mask off __GFP_COMP for the time being in the ARM dma allocator
with a note to this effect?

I believe that should do the trick, yes (AFAIK, nobody yet is
explicitly relying on a compound page from the dma allocator).

Marc can hopefully confim the fix.

--
SUSE Labs, Novell Inc.
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