Kernel: Only remap regions if memory was purged from them

Author: https://github.com/tomuta
Commit: eb1cc5d665
Pull-request: https://github.com/SerenityOS/serenity/pull/3384
Issue: https://github.com/SerenityOS/serenity/issues/3370

Kernel/VM/PurgeableVMObject.cpp

@@ -82,9 +82,12 @@ int PurgeableVMObject::purge_impl()
     }
     m_was_purged = true;
 
+    if (purged_page_count > 0) {
         for_each_region([&](auto& region) {
+            if (&region.vmobject() == this)
                region.remap();
         });
+    }
 
     return purged_page_count;
 }