[PATCH v4 62/66] mm/swapfile: Use maple tree iterator instead of vma linked list

[Liam Howlett]

* Vlastimil Babka <vbabka at suse.cz> [220120 07:46]:
> On 12/1/21 15:30, Liam Howlett wrote:
> > From: "Liam R. Howlett" <Liam.Howlett at Oracle.com>
> > 
> > Signed-off-by: Liam R. Howlett <Liam.Howlett at Oracle.com>
> 
> Acked-by: Vlastimil Babka <vbabka at suse.cz>
> 
> > ---
> >  mm/swapfile.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/swapfile.c b/mm/swapfile.c
> > index e59e08ef46e1..21c88b0944f9 100644
> > --- a/mm/swapfile.c
> > +++ b/mm/swapfile.c
> > @@ -2103,15 +2103,18 @@ static int unuse_mm(struct mm_struct *mm, unsigned int type,
> >  {
> >  	struct vm_area_struct *vma;
> >  	int ret = 0;
> > +	MA_STATE(mas, &mm->mm_mt, 0, 0);
> >  
> >  	mmap_read_lock(mm);
> > -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> > +	mas_for_each(&mas, vma, ULONG_MAX) {
> >  		if (vma->anon_vma) {
> >  			ret = unuse_vma(vma, type, frontswap,
> >  					fs_pages_to_unuse);
> >  			if (ret)
> >  				break;
> >  		}
> > +
> > +		mas_pause(&mas);
> 
> AFAIU unnecessary for the resched as we don't drop anything and keep the
> mmap_lock?
> (and without that it could be VMA_ITERATOR?)

Agreed.  This was missed with the conversion of the locking.  Thanks.

> 
> >  		cond_resched();
> >  	}
> >  	mmap_read_unlock(mm);
>