Re: mtd: kernel BUG at arch/x86/mm/pat.c:279!

From: H. Peter Anvin
Date: Sun Sep 09 2012 - 12:56:58 EST

On 09/08/2012 12:57 PM, Linus Torvalds wrote:


Anyway, that means that the BUG_ON() is likely bogus, but so is the
whole calling convention.

The 4kB range starting at 0xfffffffffffff000 sounds like a *valid*
range, but that requires that we fix the calling convention to not
have that "end" (exclusive) thing. It should either be "end"
(inclusive), or just "len".

On x86, it is definitely NOT a valid range. There is no physical addresses there, and there will never be any.

So it should either be start=0xfffffffffffff000 end=0xffffffffffffffff
or it should be start=0xfffffffffffff000 len=0x1000.

I would strongly object to the former; that kind of inclusive ranges breed a whole class of bugs by themselves.


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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