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;
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)?
> 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;
--
Dan Aloni
[email protected]
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;