On Fri, Nov 24, 2023 at 04:13:41PM +0800, Zhongkun He wrote: > > Per my understanding, the process_mbind() is implementable without > many difficult challenges， > since it is always protected by mm->mmap_lock. But task mempolicy does > not acquire any lock > in alloc_pages(). per-vma policies are protected by the mmap lock, while the task mempolicy is protected by the task lock on replacement, and task->mems_allowed (protected by task_lock). There is an update in my refactor tickets that enforces the acquisition of task_lock on mpol_set_nodemask, which prevents the need for alloc_pages to do anything else. That's not present in this patch. Basically mems_allowed deals with the majority of situations, and mmap_lock deals with per-vma mempolicy changes and migrations. ~Gregory
