From: William Lee Irwin III <wli@holomorphy.com>
To: christophpfister@bluemail.ch
Cc: linux-kernel@vger.kernel.org
Subject: Re: failure in /mm/memory.c
Date: Sat, 16 Oct 2004 05:09:11 -0700 [thread overview]
Message-ID: <20041016120911.GW5607@holomorphy.com> (raw)
In-Reply-To: <412EB75E00164E05@mssazhh-int.msg.bluewin.ch>
On Sat, Oct 16, 2004 at 12:32:35PM +0100, christophpfister@bluemail.ch wrote:
> i found a failure in function remap_pte_range in memory.c
> static inline void remap_pte_range(...)
> {
> unsigned long end;
> unsigned long pfn;
> address &= ~PMD_MASK;
> end = address + size;
> if (end > PMD_SIZE)
> end = PMD_SIZE;
> pfn = phys_addr >> PAGE_SHIFT;
> do {
> BUG_ON(!pte_none(*pte));
> if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn))) *****
> set_pte(pte, pfn_pte(pfn, prot));
> address += PAGE_SIZE;
> pfn++;
> pte++;
> } while (address && (address < end));
> }
Well, there are issues...
On Sat, Oct 16, 2004 at 12:32:35PM +0100, christophpfister@bluemail.ch wrote:
> by ****
> the condition is wrong, because it just maps the page, if it's invalid or
> reserved
> correct: if (!(pfn_valid(pfn) || PageReserved(pfn_to_page(pfn))))
> (it doesn't seems to be used, otherwise there must be bugs)
This isn't one of them. De Morgan teach us that what you wrote is just
!pfn_valid(pfn) && !PageReserved(pfn_to_page(pfn))
which would evaluate pfn_to_page() on an invalid pfn, and so nonsensical.
-- wli
next prev parent reply other threads:[~2004-10-16 12:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-16 11:32 failure in /mm/memory.c christophpfister
2004-10-16 12:09 ` William Lee Irwin III [this message]
2004-10-17 2:33 ` Alan Cox
2004-10-17 3:40 ` William Lee Irwin III
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