diff options
| -rw-r--r-- | drivers/android/binder_alloc.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index f555eebceef6..1014beb12802 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -315,12 +315,19 @@ static inline void binder_alloc_set_vma(struct binder_alloc *alloc, { unsigned long vm_start = 0; + /* + * Allow clearing the vma with holding just the read lock to allow + * munmapping downgrade of the write lock before freeing and closing the + * file using binder_alloc_vma_close(). + */ if (vma) { vm_start = vma->vm_start; alloc->vma_vm_mm = vma->vm_mm; + mmap_assert_write_locked(alloc->vma_vm_mm); + } else { + mmap_assert_locked(alloc->vma_vm_mm); } - mmap_assert_write_locked(alloc->vma_vm_mm); alloc->vma_addr = vm_start; } |