Separate out the uffd bits so it clear's what's happening.
Don't bother setting vrm->mmap_locked after unlocking, because after this
we are done anyway.
The only time we drop the mmap lock is on VMA shrink, at which point
vrm->new_len will be < vrm->old_len and the operation will not be performed
anyway, so move this code out of the if (vrm->mmap_locked) block.
All addresses returned by mremap() are page-aligned, so the
offset_in_page() check on ret seems only to be incorrectly trying to detect
whether an error occurred - explicitly check for this.
No functional change intended.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/mremap.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index d57645573e0d..87cab223f2bb 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -1731,6 +1731,15 @@ static int check_prep_vma(struct vma_remap_struct *vrm)
return 0;
}
+static void notify_uffd(struct vma_remap_struct *vrm, unsigned long to)
+{
+ struct mm_struct *mm = current->mm;
+
+ userfaultfd_unmap_complete(mm, vrm->uf_unmap_early);
+ mremap_userfaultfd_complete(vrm->uf, vrm->addr, to, vrm->old_len);
+ userfaultfd_unmap_complete(mm, vrm->uf_unmap);
+}
+
static unsigned long do_mremap(struct vma_remap_struct *vrm)
{
struct mm_struct *mm = current->mm;
@@ -1756,18 +1765,13 @@ static unsigned long do_mremap(struct vma_remap_struct *vrm)
res = vrm_implies_new_addr(vrm) ? mremap_to(vrm) : mremap_at(vrm);
out:
- if (vrm->mmap_locked) {
+ if (vrm->mmap_locked)
mmap_write_unlock(mm);
- vrm->mmap_locked = false;
-
- if (!offset_in_page(res) && vrm->mlocked && vrm->new_len > vrm->old_len)
- mm_populate(vrm->new_addr + vrm->old_len, vrm->delta);
- }
- userfaultfd_unmap_complete(mm, vrm->uf_unmap_early);
- mremap_userfaultfd_complete(vrm->uf, vrm->addr, res, vrm->old_len);
- userfaultfd_unmap_complete(mm, vrm->uf_unmap);
+ if (!IS_ERR_VALUE(res) && vrm->mlocked && vrm->new_len > vrm->old_len)
+ mm_populate(vrm->new_addr + vrm->old_len, vrm->delta);
+ notify_uffd(vrm, res);
return res;
}
--
2.50.0
