Re: Improve page refcount scalability

[Harry Yoo]

On Tue, Oct 13, 2026 at 11:43:14AM -0700, Linus Torvalds wrote:
> Comments?

There should be a limitation on how much memory can be submitted to RCU
by the page cache, otherwise will be a corner case where we have too
much unreclaimable memory waiting for the RCU subsystem to free them.

There's a similar feature, dirty throttling: when a process dirties
memory in page cache much faster than the storage can handle IO,
the kernel throttles it, otherwise it'll allow generating unbounded
amount of unreclaimable memory.

For the same reason, when a process tries to create RCU-delay-freed
pages much faster than RCU can free memory, the kernel needs to limit
that.

-- 
Cheers,e
Harry / Hyeonggon