Re: [PATCH 2.5.66-mm2] Fix page_convert_anon locking issues

From: Dave McCracken (dmccr@us.ibm.com)
Date: Wed Apr 02 2003 - 18:42:25 EST


--On Wednesday, April 02, 2003 15:38:45 -0800 Andrew Morton
<akpm@digeo.com> wrote:

> But:
>
> + /* Double check to make sure the pte page hasn't been freed */
> + if (!pmd_present(*pmd))
> + goto out_unmap;
> +
> ==> munmap, pte page is freed, reallocated for pagecache, someone
> happens to write the correct value into it.
>
> + if (page_to_pfn(page) != pte_pfn(*pte))
> + goto out_unmap;
> +
> + if (addr)
> + *addr = address;
> +

Oops. The pmd_present() check should be after the page_to_pfn() !=
pte_pfn() check.

Dave

======================================================================
Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059
dmccr@us.ibm.com T/L 678-3059

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