Re: [PATCH v2 0/3] mm: tlb swap entries batch async release

[Andrew Morton]

On Thu, 1 Aug 2024 14:30:52 +0800 zhiguojiang <justinjiang@xxxxxxxx> wrote:

> > Dumb question: why can't this be done in userspace?  The exiting
> > process does fork/exit and lets the child do all this asynchronous freeing?
> The logic optimization for kernel releasing swap entries cannot be
> implemented in userspace. The multiple exiting processes here own
> their independent mm, rather than parent and child processes share the
> same mm. Therefore, when the kernel executes multiple exiting process
> simultaneously, they will definitely occupy multiple CPU core resources
> to complete it.

What I'm asking is why not change those userspace processes so that they
fork off a child process which shares the MM (shared mm_struct) and
then the original process exits, leaving the asynchronously-running
child to clean up the MM resources.