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 | 2 ++
mm/nommu.c | 5 +++++
2 files changed, 7 insertions(+)
diff --git a/mm/mmap.c b/mm/mmap.c
index da1908730828..be289e0b693b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -448,6 +448,7 @@ void vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas)
*/
void vma_mas_remove(struct vm_area_struct *vma, struct ma_state *mas)
{
+ vma_write_lock(vma);
trace_vma_mas_szero(mas->tree, vma->vm_start, vma->vm_end - 1);
mas->index = vma->vm_start;
mas->last = vma->vm_end - 1;
@@ -2300,6 +2301,7 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
static inline int munmap_sidetree(struct vm_area_struct *vma,
struct ma_state *mas_detach)
{
+ vma_write_lock(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 b3154357ced5..7ae91337ef14 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -552,6 +552,7 @@ void vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas)
void vma_mas_remove(struct vm_area_struct *vma, struct ma_state *mas)
{
+ vma_write_lock(vma);
mas->index = vma->vm_start;
mas->last = vma->vm_end - 1;
mas_store_prealloc(mas, NULL);
@@ -1551,6 +1552,10 @@ void exit_mmap(struct mm_struct *mm)
mmap_write_lock(mm);
for_each_vma(vmi, vma) {
cleanup_vma_from_mm(vma);
+ /*
+ * No need to lock VMA because this is the only mm user and no
+ * page fault handled can race with it.
+ */
delete_vma(mm, vma);
cond_resched();
}
--
2.39.0
