On Tue, Sep 16, 2008 at 03:21:53PM -0700, Eric W. Biederman wrote:
> From: Jonathan Steel <jon.steel at esentire.com>
>
> A segmentation fault can occur in kimage_add_entry in kexec.c when
> loading a kernel image into memory. The fault occurs because a page is
> requested by calling kimage_alloc_page with gfp_mask GFP_KERNEL and the
> function may actually return a page with gfp_mask GFP_HIGHUSER. The high
> mem page is returned because it was swapped with the kernel page due to
> the kernel page being a page that will shortly be copied to.
>
> This patch ensures that kimage_alloc_page returns a page that was
> created with the correct gfp flags.
>
>
> I have verified the change and fixed the whitespace damage of the
> original patch. Jonathan did a great job of tracking this down
> after he hit the problem. -- Eric
>
> Signed-off-by: Jonathan Steel <jon.steel at esentire.com>
> Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
For what it is worth: Acked-by: Simon Horman <horms at verge.net.au>
> ---
> kernel/kexec.c | 8 +++++++-
> 1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index 59f3f0d..aef2653 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -753,8 +753,14 @@ static struct page *kimage_alloc_page(struct kimage *image,
> *old = addr | (*old & ~PAGE_MASK);
>
> /* The old page I have found cannot be a
> - * destination page, so return it.
> + * destination page, so return it if it's
> + * gfp_flags honor the ones passed in.
> */
> + if (!(gfp_mask & __GFP_HIGHMEM) &&
> + PageHighMem(old_page)) {
> + kimage_free_pages(old_page);
> + continue;
> + }
> addr = old_addr;
> page = old_page;
> break;
> --
> 1.5.3.rc6.17.g1911
>
>
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--
Simon Horman
VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
H: www.vergenet.net/~horms/ W: www.valinux.co.jp/en
