lkml.org 
[lkml]   [2002]   [Jul]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH] fix x86 page table init
    Dan Aloni wrote:
    > On Tue, Jul 30, 2002 at 09:45:17PM -0400, Brian Gerst wrote:
    >
    >>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.
    >
    >
    > In the patch below, isn't there a bootmem page leak in case !pmd_none(*pmd)?

    Whoops. That's what happens when one needs to recreate a patch from
    memory. Revised patch attached.

    --
    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 Wed Jul 31 00:32:37 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;
    + if (pmd_none(*pmd)) {
    + 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();
    + } 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;
    \
     
     \ /
      Last update: 2005-03-22 13:27    [W:0.025 / U:30.580 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site