On Thu, Feb 01, 2024 at 04:05:41PM +0800, Qi Zheng wrote: > For kernel PMD entry, we use init_mm.page_table_lock to protect it, so > there is no need to allocate and initialize the split ptlock for kernel > PMD page. I don't think this is a great idea. Maybe there's no need to initialise it, but keeping things the same between kernel & user page tables is a usually better. We don't normally allocate memory for the spinlock, it's only in debugging scenarios like LOCKDEP. I would drop this unless you have a really compelling argument to make.