Re: [PATCH v2 2/6] mm: handle swap page faults under VMA lock if page is uncontended

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

On Fri, Jun 09, 2023 at 04:25:42PM -0400, Peter Xu wrote:
> >  bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
> >  			 unsigned int flags)
> >  {
> > +	/* Can't do this if not holding mmap_lock */
> > +	if (flags & FAULT_FLAG_VMA_LOCK)
> > +		return false;
> 
> If here what we need is the page lock, can we just conditionally release
> either mmap lock or vma lock depending on FAULT_FLAG_VMA_LOCK?

See patch 5 ...