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    SubjectRe: [PATCH] Fix kunmap() argument in sg_miter_stop
    On Sat, 15 Nov 2008, Arjan van de Ven wrote:
    > >From fd5530ac75a919a20bf7951e90a2b12323e9c0a0 Mon Sep 17 00:00:00 2001
    > From: Arjan van de Ven <arjan@linux.intel.com>
    > Date: Sat, 15 Nov 2008 11:23:58 -0800
    > Subject: [PATCH] Fix kunmap() argument in sg_miter_stop
    >
    > kunmap() takes as argument the struct page that orginally got kmap()'d,
    > however the sg_miter_stop() function passed it the kernel virtual address
    > instead, resulting in "kernel BUG at arch/x86/mm/highmem_32.c:115!"

    Your patch looks like a good fix to me, but I don't get how its bug
    would manifest as highmem_32.c:115 - that's a check in kunmap_atomic(),
    whereas you're fixing a bad address to kunmap().

    I'd expect what you're fixing to manifest as an mm/highmem.c:207 -
    the BUG_ON(!vaddr) in kunmap_high(). Or have I just got in a
    terrible muddle?

    Of course, I'd love it to explain mm/highmem.c:319,
    but I can't see that either.

    Hugh

    >
    > This is moderately popular on kerneloops.org, mostly in interaction with the MMC layer.
    >
    > Reported-by: kerneloops.org
    > CC: htejun@gmail.com
    > CC: stable@kernel.org
    >
    > Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
    > ---
    > lib/scatterlist.c | 2 +-
    > 1 files changed, 1 insertions(+), 1 deletions(-)
    >
    > diff --git a/lib/scatterlist.c b/lib/scatterlist.c
    > index 8d2688f..b7b449d 100644
    > --- a/lib/scatterlist.c
    > +++ b/lib/scatterlist.c
    > @@ -395,7 +395,7 @@ void sg_miter_stop(struct sg_mapping_iter *miter)
    > WARN_ON(!irqs_disabled());
    > kunmap_atomic(miter->addr, KM_BIO_SRC_IRQ);
    > } else
    > - kunmap(miter->addr);
    > + kunmap(miter->page);
    >
    > miter->page = NULL;
    > miter->addr = NULL;
    > --
    > 1.6.0.3


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