mm: refactor va_remove_mappings

Move the VM_FLUSH_RESET_PERMS to the caller and rename the function to
better describe what it is doing.

Link: https://lkml.kernel.org/r/20230121071051.1143058-11-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc.c

@@ -2602,35 +2602,23 @@ static inline void set_area_direct_map(const struct vm_struct *area,
 			set_direct_map(area->pages[i]);
 }
 
-/* Handle removing and resetting vm mappings related to the vm_struct. */
-static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
+/*
+ * Flush the vm mapping and reset the direct map.
+ */
+static void vm_reset_perms(struct vm_struct *area)
 {
 	unsigned long start = ULONG_MAX, end = 0;
 	unsigned int page_order = vm_area_page_order(area);
-	int flush_reset = area->flags & VM_FLUSH_RESET_PERMS;
 	int flush_dmap = 0;
 	int i;
 
-	/* If this is not VM_FLUSH_RESET_PERMS memory, no need for the below. */
-	if (!flush_reset)
-		return;
-
 	/*
-	 * If not deallocating pages, just do the flush of the VM area and
-	 * return.
-	 */
-	if (!deallocate_pages) {
-		vm_unmap_aliases();
-		return;
-	}
-
-	/*
-	 * If execution gets here, flush the vm mapping and reset the direct
-	 * map. Find the start and end range of the direct mappings to make sure
+	 * Find the start and end range of the direct mappings to make sure that
 	 * the vm_unmap_aliases() flush includes the direct map.
 	 */
 	for (i = 0; i < area->nr_pages; i += 1U << page_order) {
 		unsigned long addr = (unsigned long)page_address(area->pages[i]);
+
 		if (addr) {
 			unsigned long page_size;
 
@@ -2725,7 +2713,8 @@ void vfree(const void *addr)
 		return;
 	}
 
-	vm_remove_mappings(vm, true);
+	if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS))
+		vm_reset_perms(vm);
 	for (i = 0; i < vm->nr_pages; i++) {
 		struct page *page = vm->pages[i];