diff options
Diffstat (limited to 'mm/vma.c')
| -rw-r--r-- | mm/vma.c | 58 |
1 files changed, 42 insertions, 16 deletions
@@ -416,7 +416,14 @@ static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, init_vma_prep(&vp, vma); vp.insert = new; vma_prepare(&vp); + + /* + * Get rid of huge pages and shared page tables straddling the split + * boundary. + */ vma_adjust_trans_huge(vma, vma->vm_start, addr, 0); + if (is_vm_hugetlb_page(vma)) + hugetlb_split(vma, addr); if (new_below) { vma->vm_start = addr; @@ -829,9 +836,6 @@ static struct vm_area_struct *vma_merge_existing_range(struct vma_merge_struct * err = dup_anon_vma(next, vma, &anon_dup); } - if (err) - goto abort; - /* * In nearly all cases, we expand vmg->vma. There is one exception - * merge_right where we partially span the VMA. In this case we shrink @@ -839,16 +843,11 @@ static struct vm_area_struct *vma_merge_existing_range(struct vma_merge_struct * */ expanded = !merge_right || merge_will_delete_vma; - if (commit_merge(vmg, adjust, - merge_will_delete_vma ? vma : NULL, - merge_will_delete_next ? next : NULL, - adj_start, expanded)) { - if (anon_dup) - unlink_anon_vmas(anon_dup); - - vmg->state = VMA_MERGE_ERROR_NOMEM; - return NULL; - } + if (err || commit_merge(vmg, adjust, + merge_will_delete_vma ? vma : NULL, + merge_will_delete_next ? next : NULL, + adj_start, expanded)) + goto abort; res = merge_left ? prev : next; khugepaged_enter_vma(res, vmg->flags); @@ -859,7 +858,18 @@ static struct vm_area_struct *vma_merge_existing_range(struct vma_merge_struct * abort: vma_iter_set(vmg->vmi, start); vma_iter_load(vmg->vmi); - vmg->state = VMA_MERGE_ERROR_NOMEM; + + if (anon_dup) + unlink_anon_vmas(anon_dup); + + /* + * This means we have failed to clone anon_vma's correctly, but no + * actual changes to VMAs have occurred, so no harm no foul - if the + * user doesn't want this reported and instead just wants to give up on + * the merge, allow it. + */ + if (!vmg->give_up_on_oom) + vmg->state = VMA_MERGE_ERROR_NOMEM; return NULL; } @@ -1033,9 +1043,15 @@ int vma_expand(struct vma_merge_struct *vmg) return 0; nomem: - vmg->state = VMA_MERGE_ERROR_NOMEM; if (anon_dup) unlink_anon_vmas(anon_dup); + /* + * If the user requests that we just give upon OOM, we are safe to do so + * here, as commit merge provides this contract to us. Nothing has been + * changed - no harm no foul, just don't report it. + */ + if (!vmg->give_up_on_oom) + vmg->state = VMA_MERGE_ERROR_NOMEM; return -ENOMEM; } @@ -1428,6 +1444,13 @@ static struct vm_area_struct *vma_modify(struct vma_merge_struct *vmg) if (vmg_nomem(vmg)) return ERR_PTR(-ENOMEM); + /* + * Split can fail for reasons other than OOM, so if the user requests + * this it's probably a mistake. + */ + VM_WARN_ON(vmg->give_up_on_oom && + (vma->vm_start != start || vma->vm_end != end)); + /* Split any preceding portion of the VMA. */ if (vma->vm_start < start) { int err = split_vma(vmg->vmi, vma, start, 1); @@ -1496,12 +1519,15 @@ struct vm_area_struct struct vm_area_struct *vma, unsigned long start, unsigned long end, unsigned long new_flags, - struct vm_userfaultfd_ctx new_ctx) + struct vm_userfaultfd_ctx new_ctx, + bool give_up_on_oom) { VMG_VMA_STATE(vmg, vmi, prev, vma, start, end); vmg.flags = new_flags; vmg.uffd_ctx = new_ctx; + if (give_up_on_oom) + vmg.give_up_on_oom = true; return vma_modify(&vmg); } |