diff options
Diffstat (limited to 'mm/mremap.c')
| -rw-r--r-- | mm/mremap.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index 8de77b632a20..b535438c363c 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -72,7 +72,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, struct address_space *mapping = NULL; struct mm_struct *mm = vma->vm_mm; pte_t *old_pte, *new_pte, pte; - spinlock_t *old_ptl; + spinlock_t *old_ptl, *new_ptl; if (vma->vm_file) { /* @@ -88,8 +88,15 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, new_vma->vm_truncate_count = 0; } + /* + * We don't have to worry about the ordering of src and dst + * pte locks because exclusive mmap_sem prevents deadlock. + */ old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); new_pte = pte_offset_map_nested(new_pmd, new_addr); + new_ptl = pte_lockptr(mm, new_pmd); + if (new_ptl != old_ptl) + spin_lock(new_ptl); for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, new_pte++, new_addr += PAGE_SIZE) { @@ -101,6 +108,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, set_pte_at(mm, new_addr, new_pte, pte); } + if (new_ptl != old_ptl) + spin_unlock(new_ptl); pte_unmap_nested(new_pte - 1); pte_unmap_unlock(old_pte - 1, old_ptl); if (mapping) |