mm/mmap: Lock maple tree when using mas_store_gfp()

When storing to the maple tree, take the write lock to avoid
entering/exiting the use of RCU during a write operation.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

diff --git a/mm/mmap.c b/mm/mmap.c
index 8a915579e61b3e3b8cf904ad987fd7ed38a9466d..c0852a0275cdadb0e0130efe1251ba86f9d81eda 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -454,9 +454,14 @@ static void __vma_link_file(struct vm_area_struct *vma)
  */
 static inline int vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas)
 {
+       int ret;
+
        mas->index = vma->vm_start;
        mas->last = vma->vm_end - 1;
-       return mas_store_gfp(mas, vma, GFP_KERNEL);
+       mas_lock(mas);
+       ret = mas_store_gfp(mas, vma, GFP_KERNEL);
+       mas_unlock(mas);
+       return ret;
 }
 
 /*
@@ -470,9 +475,14 @@ static inline int vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas
  */
 static inline int vma_mas_remove(struct vm_area_struct *vma, struct ma_state *mas)
 {
+       int ret;
+
        mas->index = vma->vm_start;
        mas->last = vma->vm_end - 1;
-       return mas_store_gfp(mas, NULL, GFP_KERNEL);
+       mas_lock(mas);
+       ret = mas_store_gfp(mas, NULL, GFP_KERNEL);
+       mas_unlock(mas);
+       return ret;
 }
 
 /*
@@ -2335,7 +2345,9 @@ static inline unsigned long detach_range(struct mm_struct *mm,
        mas_set(&mas, src->last + 1);
        /* Drop removed area from the tree */
        *vma = mas_find(&mas, ULONG_MAX);
+       mas_lock(src);
        mas_store_gfp(src, NULL, GFP_KERNEL);
+       mas_unlock(src);
        /* Decrement map_count */
        mm->map_count -= count;
        /* Set the upper limit */
@@ -3054,8 +3066,12 @@ static int do_brk_flags(struct ma_state *mas, struct ma_state *ma_prev,
                        }
                        vma->vm_end = addr + len;
                        vma->vm_flags |= VM_SOFTDIRTY;
-                       if (mas_store_gfp(ma_prev, vma, GFP_KERNEL))
+                       mas_lock(ma_prev);
+                       if (mas_store_gfp(ma_prev, vma, GFP_KERNEL)) {
+                               mas_unlock(ma_prev);
                                goto mas_mod_fail;
+                       }
+                       mas_unlock(ma_prev);
                        if (vma->anon_vma) {
                                anon_vma_interval_tree_post_update_vma(vma);
                                anon_vma_unlock_write(vma->anon_vma);