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

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Message-ID: <20220126022919.cgf547sxd35kxdml@revolver>
Date:   Wed, 26 Jan 2022 02:29:25 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     Vlastimil Babka <vbabka@...e.cz>
CC:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Rik van Riel <riel@...riel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michel Lespinasse <walken.cr@...il.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Minchan Kim <minchan@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Rom Lemarchand <romlem@...gle.com>
Subject: Re: [PATCH v4 52/66] mm/ksm: Use maple tree iterators instead of vma
 linked list

* Vlastimil Babka <vbabka@...e.cz> [220119 12:59]:
> On 12/1/21 15:30, Liam Howlett wrote:
> > From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> > 
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> > Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> 
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
> 
> > ---
> >  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;
> >  	}
>