--- zzzz-none-000/linux-4.4.60/mm/vmacache.c	2017-04-08 07:53:53.000000000 +0000
+++ scorpion-7490-727/linux-4.4.60/mm/vmacache.c	2021-02-04 17:41:59.000000000 +0000
@@ -6,44 +6,6 @@
 #include <linux/vmacache.h>
 
 /*
- * Flush vma caches for threads that share a given mm.
- *
- * The operation is safe because the caller holds the mmap_sem
- * exclusively and other threads accessing the vma cache will
- * have mmap_sem held at least for read, so no extra locking
- * is required to maintain the vma cache.
- */
-void vmacache_flush_all(struct mm_struct *mm)
-{
-	struct task_struct *g, *p;
-
-	count_vm_vmacache_event(VMACACHE_FULL_FLUSHES);
-
-	/*
-	 * Single threaded tasks need not iterate the entire
-	 * list of process. We can avoid the flushing as well
-	 * since the mm's seqnum was increased and don't have
-	 * to worry about other threads' seqnum. Current's
-	 * flush will occur upon the next lookup.
-	 */
-	if (atomic_read(&mm->mm_users) == 1)
-		return;
-
-	rcu_read_lock();
-	for_each_process_thread(g, p) {
-		/*
-		 * Only flush the vmacache pointers as the
-		 * mm seqnum is already set and curr's will
-		 * be set upon invalidation when the next
-		 * lookup is done.
-		 */
-		if (mm == p->mm)
-			vmacache_flush(p);
-	}
-	rcu_read_unlock();
-}
-
-/*
  * This task may be accessing a foreign mm via (for example)
  * get_user_pages()->find_vma().  The vmacache is task-local and this
  * task's vmacache pertains to a different mm (ie, its own).  There is