Re: [PATCH v4 52/66] mm/ksm: Use maple tree iterators instead of vma linked list

[Liam Howlett]

* Vlastimil Babka <vbabka@xxxxxxx> [220119 12:59]:
> On 12/1/21 15:30, Liam Howlett wrote:
> > From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
> > 
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> > Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> 
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> 
> > ---
> >  mm/ksm.c | 19 ++++++++++++-------
> >  1 file changed, 12 insertions(+), 7 deletions(-)
> > 
> > diff --git a/mm/ksm.c b/mm/ksm.c
> > index 0662093237e4..d309249c95a4 100644
> > --- a/mm/ksm.c
> > +++ b/mm/ksm.c
> > @@ -973,11 +973,13 @@ static int unmerge_and_remove_all_rmap_items(void)
> >  						struct mm_slot, mm_list);
> >  	spin_unlock(&ksm_mmlist_lock);
> >  
> > -	for (mm_slot = ksm_scan.mm_slot;
> > -			mm_slot != &ksm_mm_head; mm_slot = ksm_scan.mm_slot) {
> > +	for (mm_slot = ksm_scan.mm_slot; mm_slot != &ksm_mm_head;
> > +	     mm_slot = ksm_scan.mm_slot) {
> > +		MA_STATE(mas, &mm_slot->mm->mm_mt, 0, 0);
> 
> VMA_ITERATOR would be a bit shorter.

Yes.  I will change to the vma iterator here and below.

Thanks.

> 
> > +
> >  		mm = mm_slot->mm;
> >  		mmap_read_lock(mm);
> > -		for (vma = mm->mmap; vma; vma = vma->vm_next) {
> > +		mas_for_each(&mas, vma, ULONG_MAX) {
> >  			if (ksm_test_exit(mm))
> >  				break;
> >  			if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
> > @@ -2226,6 +2228,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
> >  	struct vm_area_struct *vma;
> >  	struct rmap_item *rmap_item;
> >  	int nid;
> > +	MA_STATE(mas, NULL, 0, 0);
> >  
> >  	if (list_empty(&ksm_mm_head.mm_list))
> >  		return NULL;
> > @@ -2283,13 +2286,14 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
> >  	}
> >  
> >  	mm = slot->mm;
> > +	mas.tree = &mm->mm_mt;
> > +	mas_set(&mas, ksm_scan.address);
> > +
> >  	mmap_read_lock(mm);
> >  	if (ksm_test_exit(mm))
> > -		vma = NULL;
> > -	else
> > -		vma = find_vma(mm, ksm_scan.address);
> > +		goto no_vmas;
> >  
> > -	for (; vma; vma = vma->vm_next) {
> > +	mas_for_each(&mas, vma, ULONG_MAX) {
> >  		if (!(vma->vm_flags & VM_MERGEABLE))
> >  			continue;
> >  		if (ksm_scan.address < vma->vm_start)
> > @@ -2327,6 +2331,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
> >  	}
> >  
> >  	if (ksm_test_exit(mm)) {
> > +no_vmas:
> >  		ksm_scan.address = 0;
> >  		ksm_scan.rmap_list = &slot->rmap_list;
> >  	}
>