diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 60 |
1 files changed, 29 insertions, 31 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index eae90af60ea..3f758c7f4c8 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1603,39 +1603,19 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) EXPORT_SYMBOL(find_vma); -/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ +/* + * Same as find_vma, but also return a pointer to the previous VMA in *pprev. + * Note: pprev is set to NULL when return value is NULL. + */ struct vm_area_struct * find_vma_prev(struct mm_struct *mm, unsigned long addr, struct vm_area_struct **pprev) { - struct vm_area_struct *vma = NULL, *prev = NULL; - struct rb_node *rb_node; - if (!mm) - goto out; - - /* Guard against addr being lower than the first VMA */ - vma = mm->mmap; - - /* Go through the RB tree quickly. */ - rb_node = mm->mm_rb.rb_node; - - while (rb_node) { - struct vm_area_struct *vma_tmp; - vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); - - if (addr < vma_tmp->vm_end) { - rb_node = rb_node->rb_left; - } else { - prev = vma_tmp; - if (!prev->vm_next || (addr < prev->vm_next->vm_end)) - break; - rb_node = rb_node->rb_right; - } - } + struct vm_area_struct *vma; -out: - *pprev = prev; - return prev ? prev->vm_next : vma; + vma = find_vma(mm, addr); + *pprev = vma ? vma->vm_prev : NULL; + return vma; } /* @@ -2322,13 +2302,16 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, struct vm_area_struct *new_vma, *prev; struct rb_node **rb_link, *rb_parent; struct mempolicy *pol; + bool faulted_in_anon_vma = true; /* * If anonymous vma has not yet been faulted, update new pgoff * to match new location, to increase its chance of merging. */ - if (!vma->vm_file && !vma->anon_vma) + if (unlikely(!vma->vm_file && !vma->anon_vma)) { pgoff = addr >> PAGE_SHIFT; + faulted_in_anon_vma = false; + } find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, @@ -2337,9 +2320,24 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, /* * Source vma may have been merged into new_vma */ - if (vma_start >= new_vma->vm_start && - vma_start < new_vma->vm_end) + if (unlikely(vma_start >= new_vma->vm_start && + vma_start < new_vma->vm_end)) { + /* + * The only way we can get a vma_merge with + * self during an mremap is if the vma hasn't + * been faulted in yet and we were allowed to + * reset the dst vma->vm_pgoff to the + * destination address of the mremap to allow + * the merge to happen. mremap must change the + * vm_pgoff linearity between src and dst vmas + * (in turn preventing a vma_merge) to be + * safe. It is only safe to keep the vm_pgoff + * linear if there are no pages mapped yet. + */ + VM_BUG_ON(faulted_in_anon_vma); *vmap = new_vma; + } else + anon_vma_moveto_tail(new_vma); } else { new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); if (new_vma) { |