Re: [LSF/MM/BPF TOPIC] Measuring limits and enhancing buffered IO

Matthew Wilcox
2024-02-28T18:05:10Z

On Wed, Feb 28, 2024 at 12:34:41PM -0500, Kent Overstreet wrote:
> But even better would be if we could get lockdep to support folio locks,
> then we could define a lockdep comparison function. Of course, there's
> no place to stick a lockdep map, but I think technically lockdep could
> do everything it needs to do without state in the lock itself, if only
> that code didn't make my eyes bleed whenever I have to dig into it...

I don't think lockdep can support folio locks. They're taken in process
context and (for ->read_folio) released in interrupt context. Also we
can return to userspace while holding folio locks (I believe ...)

DEPT claims to be able to handle them, but I haven't looked in detail.