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From: "H. Peter Anvin" <hpa@zytor.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>,
	Sasha Levin <levinsasha928@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	dwmw2@infradead.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	linux-mtd@lists.infradead.org, linux-mm <linux-mm@kvack.org>,
	Dave Jones <davej@redhat.com>
Subject: Re: mtd: kernel BUG at arch/x86/mm/pat.c:279!
Date: Sun, 09 Sep 2012 09:56:17 -0700	[thread overview]
Message-ID: <504CCA31.2000003@zytor.com> (raw)
In-Reply-To: <CA+55aFzeKcV5hROLJE31dNi3SEs+s6o0LL=96Kh8QGHPx=aZnA@mail.gmail.com>

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

	-hpa

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

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  parent reply	other threads:[~2012-09-09 16:56 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-29  8:48 mtd: kernel BUG at arch/x86/mm/pat.c:279! Sasha Levin
2012-07-30 11:00 ` Sasha Levin
2012-09-07 16:55 ` Sasha Levin
2012-09-07 18:14   ` Linus Torvalds
2012-09-07 22:42     ` Suresh Siddha
2012-09-07 23:09       ` Linus Torvalds
2012-09-07 23:54         ` Suresh Siddha
2012-09-08 19:57           ` Linus Torvalds
2012-09-09 14:56             ` Suresh Siddha
2012-09-09 15:31               ` Linus Torvalds
2012-09-09 17:01                 ` H. Peter Anvin
2012-09-12 10:50               ` Sasha Levin
2012-09-12 10:56                 ` Sasha Levin
2012-09-28  9:00                   ` Sasha Levin
2012-09-28 16:44                     ` Linus Torvalds
2012-09-28 18:05                       ` Artem Bityutskiy
2012-09-28 19:13                         ` Linus Torvalds
2012-09-28 19:44                           ` Sasha Levin
2012-09-28 19:04                       ` David Woodhouse
2012-09-28 19:15                         ` richard -rw- weinberger
2012-09-28 19:18                           ` richard -rw- weinberger
2012-09-29 16:11                         ` David Woodhouse
2012-09-29 16:34                           ` David Woodhouse
2012-09-09 16:56             ` H. Peter Anvin [this message]
2012-09-09 19:04               ` David Woodhouse
2012-09-09 20:33                 ` H. Peter Anvin
2012-09-10  5:17               ` Sasha Levin
2012-09-08  8:10         ` Sasha Levin

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