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    Subject[PATCH] fix x86 page table init
    The recent changes to the x86 page table init reintroduced a bug with 
    the 4k pagetables. The page table must be filled with entries before it
    is inserted into the pmd or else you risk a tlb miss on a kernel code
    page causing an oops. This patch takes a different approach than before
    - it allows for reuse of the boot pagetable pages instead of allocating
    new ones.

    --
    Brian Gerst
    diff -urN linux-bk/arch/i386/mm/init.c linux/arch/i386/mm/init.c
    --- linux-bk/arch/i386/mm/init.c Tue Jul 30 20:59:27 2002
    +++ linux/arch/i386/mm/init.c Tue Jul 30 21:02:41 2002
    @@ -70,10 +70,14 @@
    */
    static pte_t * __init one_page_table_init(pmd_t *pmd)
    {
    - pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
    - set_pmd(pmd, __pmd(__pa(page_table) | _KERNPG_TABLE));
    - if (page_table != pte_offset_kernel(pmd, 0))
    - BUG();
    + pte_t *page_table;
    + page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
    + if (pmd_none(*pmd)) {
    + set_pmd(pmd, __pmd(__pa(page_table) | _KERNPG_TABLE));
    + if (page_table != pte_offset_kernel(pmd, 0))
    + BUG();
    + } else
    + page_table = pte_offset_kernel(pmd, 0);

    return page_table;
    }
    @@ -107,9 +111,7 @@

    pmd = pmd_offset(pgd, vaddr);
    for (; (pmd_ofs < PTRS_PER_PMD) && (vaddr != end); pmd++, pmd_ofs++) {
    - if (pmd_none(*pmd))
    - one_page_table_init(pmd);
    -
    + one_page_table_init(pmd);
    vaddr += PMD_SIZE;
    }
    pmd_ofs = 0;
    \
     
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