Smatch has observed that pte_offset_map_lock() is now allowed to fail,
and then ptl should not be unlocked. Use -EAGAIN here like elsewhere.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
Axel, Peter: this seems right as a fix to the patch in mm-unstable;
but in preparing this, I noticed mfill_atomic()'s code before calling
mfill_atomic_pte(), and think that my original choice of -EFAULT was
therefore better than -EAGAIN for all of these; and that mfill_atomic()'s
BUG_ONs there would be better deleted (and is its BUG_ON(folio) safe??).
Something one of us should address, after this fixup is in akpm's tree.
mm/userfaultfd.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -300,7 +300,10 @@ static int mfill_atomic_pte_poison(pmd_t *dst_pmd,
spinlock_t *ptl;
_dst_pte = make_pte_marker(PTE_MARKER_POISONED);
+ ret = -EAGAIN;
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+ if (!dst_pte)
+ goto out;
if (mfill_file_over_size(dst_vma, dst_addr)) {
ret = -EFAULT;
@@ -319,6 +322,7 @@ static int mfill_atomic_pte_poison(pmd_t *dst_pmd,
ret = 0;
out_unlock:
pte_unmap_unlock(dst_pte, ptl);
+out:
return ret;
}
