[PATCH v3 14/35] mm/mmap: move VMA locking before vma_adjust_trans_huge call

[Suren Baghdasaryan]

vma_adjust_trans_huge() modifies the VMA and such modifications should
be done after VMA is marked as being written. Therefore move VMA flag
modifications before vma_adjust_trans_huge() so that VMA is marked
before all these modifications.

Signed-off-by: Suren Baghdasaryan <sur...@google.com>
---
 mm/mmap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 06c0f6686de8..c5f2ddf17b87 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2910,11 +2910,12 @@ static int do_brk_flags(struct vma_iterator *vmi, 
struct vm_area_struct *vma,
                if (vma_iter_prealloc(vmi))
                        goto unacct_fail;
 
+               /* Set flags first to implicitly lock the VMA before updates */
+               vm_flags_set(vma, VM_SOFTDIRTY);
                vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
                init_vma_prep(&vp, vma);
                vma_prepare(&vp);
                vma->vm_end = addr + len;
-               vm_flags_set(vma, VM_SOFTDIRTY);
                vma_iter_store(vmi, vma);
 
                vma_complete(&vp, vmi, mm);
-- 
2.39.1