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    SubjectRe: [PATCH RESEND] early_ioremap has a fencepost error

    * Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

    > Can we get this into 2.6.27.x at some point as its a regression and a
    > crash on boot for some users moving from 2.6.26

    yes, have your fix patch from yesterday in tip/x86/urgent already, with
    a stable@kernel.org tag included as well - see below. Thanks Alan!

    Ingo

    -------------->
    From dd5698f42a5f2b494c3e811598403f105b00f4f2 Mon Sep 17 00:00:00 2001
    From: Alan Cox <alan@redhat.com>
    Date: Fri, 10 Oct 2008 10:46:45 +0100
    Subject: [PATCH] x86, early_ioremap: fix fencepost error

    The x86 implementation of early_ioremap has an off by one error. If we get
    an object which ends on the first byte of a page we undermap by one page and
    this causes a crash on boot with the ASUS P5QL whose DMI table happens to fit
    this alignment.

    The size computation is currently

    last_addr = phys_addr + size - 1;
    npages = (PAGE_ALIGN(last_addr) - phys_addr)

    (Consider a request for 1 byte at alignment 0...)

    Closes #11693

    Debugging work by Ian Campbell/Felix Geyer

    Signed-off-by: Alan Cox <alan@rehat.com>
    Cc: <stable@kernel.org>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    arch/x86/mm/ioremap.c | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
    index d4b6e6a..d0975fc 100644
    --- a/arch/x86/mm/ioremap.c
    +++ b/arch/x86/mm/ioremap.c
    @@ -595,7 +595,7 @@ void __init *early_ioremap(unsigned long phys_addr, unsigned long size)
    */
    offset = phys_addr & ~PAGE_MASK;
    phys_addr &= PAGE_MASK;
    - size = PAGE_ALIGN(last_addr) - phys_addr;
    + size = PAGE_ALIGN(last_addr + 1) - phys_addr;

    /*
    * Mappings have to fit in the FIX_BTMAP area.

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