From: Ed L Cashin <ecashin@uga.edu>
To: Ravi <kravi26@yahoo.com>
Cc: linux-mm@kvack.org, kernelnewbies@nl.linux.org
Subject: Re: BUG_ON in remap_pte_range: Why?
Date: Wed, 21 May 2003 00:20:32 -0400 [thread overview]
Message-ID: <873cj93p7z.fsf@cs.uga.edu> (raw)
In-Reply-To: <20030520202728.42626.qmail@web12308.mail.yahoo.com> (Ravi's message of "Tue, 20 May 2003 13:27:28 -0700 (PDT)")
Ravi <kravi26@yahoo.com> writes:
> Hi,
>
> I am looking at the latest mm/memory.c on Bitkeeper.
> The comment for remap_pte_range() says "maps a range of
> physical memory into the requested pages. the old mappings
> are removed". But the code has this check:
>
> BUG_ON(!pte_none(*pte));
>
> Why is it a bug to have a valid PTE when remap_pte_range()
> is called? The 2.4 version of this fucntion cleared the
> old PTE using ptep_get_and_clear() and then installed
> a new one. Why was this changed?
It used to be a call to forget_pte, and, as Flavio Bruno Leitner
pointed out, wli changed it last year:
http://www.ussg.iu.edu/hypermail/linux/kernel/0206.0/0053.html
... making forget_pte into a macro, which has since been completely
inlined. The comment that used to be above the macro was this:
bug check to be sure pte's are unmapped when no longer used
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prev parent reply other threads:[~2003-05-21 4:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-20 20:27 Ravi
2003-05-21 4:20 ` Ed L Cashin [this message]
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