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[PATCH] freepgt: free_pgtables from FIRST_USER_ADDRESS

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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 <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Hugh Dickins 2005-04-19 13:29:19 -07:00 committed by Linus Torvalds
parent 021740dc30
commit e2cdef8c84
1 changed files with 8 additions and 3 deletions
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11
mm/mmap.c
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@ -1612,6 +1612,11 @@ static void unmap_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
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_struct *mm,
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