hugetlb: check for anon_vma prior to folio allocation

Commit 9acad7ba3e25 ("hugetlb: use vmf_anon_prepare() instead of
anon_vma_prepare()") may bailout after allocating a folio if we do not
hold the mmap lock.  When this occurs, vmf_anon_prepare() will release the
vma lock.  Hugetlb then attempts to call restore_reserve_on_error(), which
depends on the vma lock being held.

We can move vmf_anon_prepare() prior to the folio allocation in order to
avoid calling restore_reserve_on_error() without the vma lock.

Link: https://lkml.kernel.org/r/ZiFqSrSRLhIV91og@fedora
Fixes: 9acad7ba3e25 ("hugetlb: use vmf_anon_prepare() instead of anon_vma_prepare()")
Reported-by: [email protected]
Signed-off-by: Vishal Moola (Oracle) <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions