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SubjectRe: [PATCH 1/5] Add pagetable allocation notifiers
Chris Wright wrote:

>* Zachary Amsden (zach@vmware.com) wrote:
>
>
>>--- linux-2.6.13.orig/arch/i386/mm/init.c 2005-08-24 09:31:05.000000000 -0700
>>+++ linux-2.6.13/arch/i386/mm/init.c 2005-08-24 09:31:31.000000000 -0700
>>@@ -79,6 +79,7 @@ static pte_t * __init one_page_table_ini
>> {
>> if (pmd_none(*pmd)) {
>> pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
>>+ SetPagePTE(virt_to_page(page_table));
>>
>>
>
>Xen has this on one_md_table_init() as well for pmd.
>
>
>
>> set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
>> if (page_table != pte_offset_kernel(pmd, 0))
>> BUG();
>>Index: linux-2.6.13/arch/i386/mm/pageattr.c
>>===================================================================
>>--- linux-2.6.13.orig/arch/i386/mm/pageattr.c 2005-08-24 09:31:05.000000000 -0700
>>+++ linux-2.6.13/arch/i386/mm/pageattr.c 2005-08-24 09:31:31.000000000 -0700
>>@@ -52,8 +52,9 @@ static struct page *split_large_page(uns
>> address = __pa(address);
>> addr = address & LARGE_PAGE_MASK;
>> pbase = (pte_t *)page_address(base);
>>+ SetPagePTE(virt_to_page(pbase));
>> for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
>>- set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
>>+ set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
>>
>>
>
>No need to intersperse whitespace cleanups.
>
>
>
>> addr == address ? prot : PAGE_KERNEL));
>> }
>> return base;
>>@@ -146,6 +147,7 @@ __change_page_attr(struct page *page, pg
>> BUG_ON(!page_count(kpte_page));
>>
>> if (cpu_has_pse && (page_count(kpte_page) == 1)) {
>>+ ClearPagePTE(virt_to_page(kpte));
>> list_add(&kpte_page->lru, &df_list);
>> revert_page(kpte_page, address);
>> }
>>Index: linux-2.6.13/arch/i386/mm/pgtable.c
>>===================================================================
>>--- linux-2.6.13.orig/arch/i386/mm/pgtable.c 2005-08-24 09:31:05.000000000 -0700
>>+++ linux-2.6.13/arch/i386/mm/pgtable.c 2005-08-24 09:40:22.000000000 -0700
>>@@ -209,6 +209,7 @@ void pgd_ctor(void *pgd, kmem_cache_t *c
>>
>> if (PTRS_PER_PMD == 1) {
>> memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
>>+ SetPagePDE(virt_to_page(pgd));
>> spin_lock_irqsave(&pgd_lock, flags);
>> }
>>
>>@@ -227,6 +228,7 @@ void pgd_dtor(void *pgd, kmem_cache_t *c
>> {
>> unsigned long flags; /* can be called from interrupt context */
>>
>>+ ClearPagePDE(virt_to_page(pgd));
>>
>>
>
>This reminds me, Xen had some unconditional use of pgd_dtor I need
>to go back and look at.
>
>

It looks quite unneeded:

void pgd_dtor(void *pgd, kmem_cache_t *cache, unsigned long unused)
{
unsigned long flags; /* can be called from interrupt context */

if (HAVE_SHARED_KERNEL_PMD) <--- /* PAE */
return;

spin_lock_irqsave(&pgd_lock, flags);
pgd_list_del(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
}

Leaving the dtor conditional saves an indirect function call ;)

Zach
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