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Diffstat (limited to 'mm/vma.c')
-rw-r--r--mm/vma.c70
1 files changed, 50 insertions, 20 deletions
diff --git a/mm/vma.c b/mm/vma.c
index 7621384d64cf..140f7017bb63 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -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;
}
@@ -1417,24 +1433,35 @@ int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
static struct vm_area_struct *vma_modify(struct vma_merge_struct *vmg)
{
struct vm_area_struct *vma = vmg->vma;
+ unsigned long start = vmg->start;
+ unsigned long end = vmg->end;
struct vm_area_struct *merged;
/* First, try to merge. */
merged = vma_merge_existing_range(vmg);
if (merged)
return merged;
+ 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 < vmg->start) {
- int err = split_vma(vmg->vmi, vma, vmg->start, 1);
+ if (vma->vm_start < start) {
+ int err = split_vma(vmg->vmi, vma, start, 1);
if (err)
return ERR_PTR(err);
}
/* Split any trailing portion of the VMA. */
- if (vma->vm_end > vmg->end) {
- int err = split_vma(vmg->vmi, vma, vmg->end, 0);
+ if (vma->vm_end > end) {
+ int err = split_vma(vmg->vmi, vma, end, 0);
if (err)
return ERR_PTR(err);
@@ -1492,12 +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);
}