From: Hugh Dickins The patches to free_pgtables by vma left problems on any architectures which leave some user address page table entries unencapsulated by vma. Andi has fixed the 32-bit vDSO on x86_64 to use a vma. Now fix arm (and arm26), whose first PAGE_SIZE is reserved (perhaps) for machine vectors. Our calls to free_pgtables must not touch that area, and exit_mmap's BUG_ON(nr_ptes) must allow that arm's get_pgd_slow may (or may not) have allocated an extra page table, which its free_pgd_slow would free later. FIRST_USER_PGD_NR has misled me and others: until all the arches define FIRST_USER_ADDRESS instead, a hack in mmap.c to derive one from t'other. This patch fixes the bugs, the remaining patches just clean it up. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton --- 25-akpm/mm/mmap.c | 11 ++++++++--- 1 files changed, 8 insertions(+), 3 deletions(-) diff -puN mm/mmap.c~freepgt2-free_pgtables-from-first_user_address mm/mmap.c --- 25/mm/mmap.c~freepgt2-free_pgtables-from-first_user_address 2005-04-06 18:21:58.000000000 -0700 +++ 25-akpm/mm/mmap.c 2005-04-06 18:21:58.000000000 -0700 @@ -1612,6 +1612,11 @@ static void unmap_vma_list(struct mm_str validate_mm(mm); } +#ifndef FIRST_USER_ADDRESS /* temporary hack */ +#define THIS_IS_ARM FIRST_USER_PGD_NR +#define FIRST_USER_ADDRESS (THIS_IS_ARM * PAGE_SIZE) +#endif + /* * Get rid of page table information in the indicated region. * @@ -1630,7 +1635,7 @@ static void unmap_region(struct mm_struc tlb = tlb_gather_mmu(mm, 0); unmap_vmas(&tlb, mm, vma, start, end, &nr_accounted, NULL); vm_unacct_memory(nr_accounted); - free_pgtables(&tlb, vma, prev? prev->vm_end: 0, + free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, next? next->vm_start: 0); tlb_finish_mmu(tlb, start, end); spin_unlock(&mm->page_table_lock); @@ -1910,7 +1915,7 @@ void exit_mmap(struct mm_struct *mm) /* Use -1 here to ensure all VMAs in the mm are unmapped */ end = unmap_vmas(&tlb, mm, vma, 0, -1, &nr_accounted, NULL); vm_unacct_memory(nr_accounted); - free_pgtables(&tlb, vma, 0, 0); + free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); tlb_finish_mmu(tlb, 0, end); mm->mmap = mm->mmap_cache = NULL; @@ -1931,7 +1936,7 @@ void exit_mmap(struct mm_struct *mm) vma = next; } - BUG_ON(mm->nr_ptes); /* This is just debugging */ + BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); } /* Insert vm structure into process list sorted by address _