userfaultfd: release page in error path to avoid BUG_ON

[linux-2.6-microblaze.git] / mm / shmem.c

diff --git a/mm/shmem.c b/mm/shmem.c
index eb131b9..5d46611 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2361,8 +2361,18 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
        pgoff_t offset, max_off;
 
        ret = -ENOMEM;
-       if (!shmem_inode_acct_block(inode, 1))
+       if (!shmem_inode_acct_block(inode, 1)) {
+               /*
+                * We may have got a page, returned -ENOENT triggering a retry,
+                * and now we find ourselves with -ENOMEM. Release the page, to
+                * avoid a BUG_ON in our caller.
+                */
+               if (unlikely(*pagep)) {
+                       put_page(*pagep);
+                       *pagep = NULL;
+               }
                goto out;
+       }
 
        if (!*pagep) {
                page = shmem_alloc_page(gfp, info, pgoff);