From: "Chen, Kenneth W" I don't think we need to call hugetlb_clean_stale_pgtable() anymore in 2.6.13 because of the rework with free_pgtables(). It now collect all the pte page at the time of munmap. It used to only collect page table pages when entire one pgd can be freed and left with staled pte pages. Not anymore with 2.6.13. This function will never be called and We should turn it into a BUG_ON. I also spotted two problems here, not Adam's fault :-) (1) in huge_pte_alloc(), it looks like a bug to me that pud is not checked before calling pmd_alloc() (2) in hugetlb_clean_stale_pgtable(), it also missed a call to pmd_free_tlb. I think a tlb flush is required to flush the mapping for the page table itself when we clear out the pmd pointing to a pte page. However, since hugetlb_clean_stale_pgtable() is never called, so it won't trigger the bug. Signed-off-by: Ken Chen Cc: Adam Litke Signed-off-by: Andrew Morton --- arch/i386/mm/hugetlbpage.c | 23 +++-------------------- include/asm-i386/page.h | 1 - include/asm-x86_64/page.h | 1 - include/linux/hugetlb.h | 6 ------ 4 files changed, 3 insertions(+), 28 deletions(-) diff -puN arch/i386/mm/hugetlbpage.c~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc arch/i386/mm/hugetlbpage.c --- devel/arch/i386/mm/hugetlbpage.c~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc 2005-08-30 17:41:41.000000000 -0700 +++ devel-akpm/arch/i386/mm/hugetlbpage.c 2005-08-30 17:41:41.000000000 -0700 @@ -22,20 +22,14 @@ pte_t *huge_pte_alloc(struct mm_struct * { pgd_t *pgd; pud_t *pud; - pmd_t *pmd; pte_t *pte = NULL; pgd = pgd_offset(mm, addr); pud = pud_alloc(mm, pgd, addr); - pmd = pmd_alloc(mm, pud, addr); + if (pud) + pte = (pte_t *) pmd_alloc(mm, pud, addr); + BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); - if (!pmd) - goto out; - - pte = (pte_t *) pmd; - if (!pte_none(*pte) && !pte_huge(*pte)) - hugetlb_clean_stale_pgtable(pte); -out: return pte; } @@ -130,17 +124,6 @@ follow_huge_pmd(struct mm_struct *mm, un } #endif -void hugetlb_clean_stale_pgtable(pte_t *pte) -{ - pmd_t *pmd = (pmd_t *) pte; - struct page *page; - - page = pmd_page(*pmd); - pmd_clear(pmd); - dec_page_state(nr_page_table_pages); - page_cache_release(page); -} - /* x86_64 also uses this file */ #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA diff -puN include/asm-i386/page.h~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc include/asm-i386/page.h --- devel/include/asm-i386/page.h~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc 2005-08-30 17:41:41.000000000 -0700 +++ devel-akpm/include/asm-i386/page.h 2005-08-30 17:41:41.000000000 -0700 @@ -68,7 +68,6 @@ typedef struct { unsigned long pgprot; } #define HPAGE_MASK (~(HPAGE_SIZE - 1)) #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) #define HAVE_ARCH_HUGETLB_UNMAPPED_AREA -#define ARCH_HAS_HUGETLB_CLEAN_STALE_PGTABLE #endif #define pgd_val(x) ((x).pgd) diff -puN include/asm-x86_64/page.h~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc include/asm-x86_64/page.h --- devel/include/asm-x86_64/page.h~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc 2005-08-30 17:41:41.000000000 -0700 +++ devel-akpm/include/asm-x86_64/page.h 2005-08-30 17:41:41.000000000 -0700 @@ -28,7 +28,6 @@ #define HPAGE_SIZE ((1UL) << HPAGE_SHIFT) #define HPAGE_MASK (~(HPAGE_SIZE - 1)) #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) -#define ARCH_HAS_HUGETLB_CLEAN_STALE_PGTABLE #ifdef __KERNEL__ #ifndef __ASSEMBLY__ diff -puN include/linux/hugetlb.h~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc include/linux/hugetlb.h --- devel/include/linux/hugetlb.h~remove-hugetlb_clean_stale_pgtable-and-fix-huge_pte_alloc 2005-08-30 17:41:41.000000000 -0700 +++ devel-akpm/include/linux/hugetlb.h 2005-08-30 17:41:41.000000000 -0700 @@ -70,12 +70,6 @@ pte_t huge_ptep_get_and_clear(struct mm_ void hugetlb_prefault_arch_hook(struct mm_struct *mm); #endif -#ifndef ARCH_HAS_HUGETLB_CLEAN_STALE_PGTABLE -#define hugetlb_clean_stale_pgtable(pte) BUG() -#else -void hugetlb_clean_stale_pgtable(pte_t *pte); -#endif - #else /* !CONFIG_HUGETLB_PAGE */ static inline int is_vm_hugetlb_page(struct vm_area_struct *vma) _