linux-kernel - Re: [PATCH v4 58/66] mm/mremap: Use vma

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Message-ID: <20220126165939.reu2pu6wztmr274f@revolver>
Date:   Wed, 26 Jan 2022 16:59:46 +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 58/66] mm/mremap: Use vma_find() instead of vma linked
 list

* Vlastimil Babka <vbabka@...e.cz> [220120 07:27]:
> On 12/1/21 15:30, Liam Howlett wrote:
> > From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> > 
> > Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> 
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
> 
> > ---
> >  mm/mremap.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/mm/mremap.c b/mm/mremap.c
> > index b09e107cd18b..4ad39c985d04 100644
> > --- a/mm/mremap.c
> > +++ b/mm/mremap.c
> > @@ -713,7 +713,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
> >  	if (excess) {
> >  		vma->vm_flags |= VM_ACCOUNT;
> >  		if (split)
> > -			vma->vm_next->vm_flags |= VM_ACCOUNT;
> > +			find_vma(mm, vma->vm_end)->vm_flags |= VM_ACCOUNT;
> >  	}
> >  
> >  	return new_addr;
> > @@ -869,9 +869,11 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
> >  static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
> >  {
> >  	unsigned long end = vma->vm_end + delta;
> > +	struct vm_area_struct *next;
> >  	if (end < vma->vm_end) /* overflow */
> >  		return 0;
> > -	if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
> > +	next = find_vma(vma->vm_mm, vma->vm_end);
> > +	if (next && next->vm_start < end) /* intersection */
> 
> Could just use find_vma_intersection()?

Yes!  Then next is not needed.  That will be nice.

> 
> >  		return 0;
> >  	if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
> >  			      0, MAP_FIXED) & ~PAGE_MASK)
>