Write-locking VMAs before isolating them ensures that page fault
handlers don't operate on isolated VMAs.
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
---
mm/mmap.c | 1 +
mm/nommu.c | 5 +++++
2 files changed, 6 insertions(+)
diff --git a/mm/mmap.c b/mm/mmap.c
index b3c247073aa0..5bdfd087b632 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2261,6 +2261,7 @@ int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
static inline int munmap_sidetree(struct vm_area_struct *vma,
struct ma_state *mas_detach)
{
+ vma_start_write(vma);
mas_set_range(mas_detach, vma->vm_start, vma->vm_end - 1);
if (mas_store_gfp(mas_detach, vma, GFP_KERNEL))
return -ENOMEM;
diff --git a/mm/nommu.c b/mm/nommu.c
index 57ba243c6a37..2ab162d773e2 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -588,6 +588,7 @@ static int delete_vma_from_mm(struct vm_area_struct *vma)
current->pid);
return -ENOMEM;
}
+ vma_start_write(vma);
cleanup_vma_from_mm(vma);
/* remove from the MM's tree and list */
@@ -1519,6 +1520,10 @@ void exit_mmap(struct mm_struct *mm)
*/
mmap_write_lock(mm);
for_each_vma(vmi, vma) {
+ /*
+ * No need to lock VMA because this is the only mm user and no
+ * page fault handled can race with it.
+ */
cleanup_vma_from_mm(vma);
delete_vma(mm, vma);
cond_resched();
--
2.39.1
