Pagefault handlers might need to fire MMU notifications while a new
notifier is being registered. Modify mm_take_all_locks to mark all VMAs
as locked and prevent this race with fault handlers that would hold VMA
locks.
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
---
mm/mmap.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/mmap.c b/mm/mmap.c
index b31cc97c2803..1edfcd384f5e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3538,6 +3538,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
* hugetlb mapping);
* - all i_mmap_rwsem locks;
* - all anon_vma->rwseml
+ * - all vmas marked locked
*
* We can take all locks within these types randomly because the VM code
* doesn't nest them and we protected from parallel mm_take_all_locks() by
@@ -3579,6 +3580,7 @@ int mm_take_all_locks(struct mm_struct *mm)
if (vma->anon_vma)
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
vm_lock_anon_vma(mm, avc->anon_vma);
+ vma_mark_locked(vma);
}
return 0;
@@ -3636,6 +3638,7 @@ void mm_drop_all_locks(struct mm_struct *mm)
mmap_assert_write_locked(mm);
BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
+ vma_mark_unlocked_all(mm);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->anon_vma)
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
--
2.37.2.789.g6183377224-goog
