linux-kernel - Re: [PATCH v7 00/70] Introducing the Maple Tree

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Message-ID: <20220419174757.2tptlbkebiletmck@revolver>
Date:   Tue, 19 Apr 2022 17:50:37 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     Yu Zhao <yuzhao@...gle.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        "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>
Subject: Re: [PATCH v7 00/70] Introducing the Maple Tree

* Yu Zhao <yuzhao@...gle.com> [220414 12:57]:
> On Thu, Apr 14, 2022 at 7:57 AM Liam Howlett <liam.howlett@...cle.com> wrote:
> >
> > * Andrew Morton <akpm@...ux-foundation.org> [220414 02:51]:
> > > On Mon, 4 Apr 2022 14:35:26 +0000 Liam Howlett <liam.howlett@...cle.com> wrote:
> > >
> > > > Please add this patch set to your branch.  They are based on v5.18-rc1.
> > >
> > > Do we get a nice [0/n] cover letter telling us all about this?
> > >
> > > I have that all merged up and it compiles.
> > >
> > > https://lkml.kernel.org/r/20220402094550.129-1-lipeifeng@oppo.com and
> > > https://lkml.kernel.org/r/20220412081014.399-1-lipeifeng@oppo.com are
> > > disabled for now.
> > >
> > >
> > > Several patches were marked
> > >
> > > From: Liam
> > > Signed-off-by: Matthew
> > > Signed-off-by: Liam
> > >
> > > Which makes me wonder whether the attribution was correct.  Please
> > > double-check.
> >
> > I'll have a look, thanks.
> >
> > >
> > >
> > >
> > > I made a lame attempt to fix up mglru's get_next_vma(), and it probably
> > > wants a revisit in the maple-tree world anyway.  Please check this and
> > > send me a better version ;)
> >
> > What you have below will function, but there is probably a more maple
> > way of doing things.  Happy to help get the sap flowing - it is that
> > time of the year after all ;)
> 
> Thanks. Please let me know when the more maple way is ready. I'll test with it.

Here is a patch to replace the fixup below.  I suspect we could do
better, but for now I just used a VMA_ITERATOR.

This could be put into d2035fb88f9f "mm: multi-gen LRU: support page
table walks" if multi-gen LRU goes in after the maple tree.


> 
> Also I noticed, for the end address to walk_page_range(), Matthew used
> -1 and you used ULONG_MAX in the maple branch; Andrew used TASK_SIZE
> below. Having a single value throughout would be great.
> 
> > > --- a/mm/vmscan.c~mglru-vs-maple-tree
> > > +++ a/mm/vmscan.c
> > > @@ -3704,7 +3704,7 @@ static bool get_next_vma(struct mm_walk
> > >
> > >       while (walk->vma) {
> > >               if (next >= walk->vma->vm_end) {
> > > -                     walk->vma = walk->vma->vm_next;
> > > +                     walk->vma = find_vma(walk->mm, walk->vma->vm_end);
> > >                       continue;
> > >               }
> > >
> > > @@ -3712,7 +3712,7 @@ static bool get_next_vma(struct mm_walk
> > >                       return false;
> > >
> > >               if (should_skip_vma(walk->vma->vm_start, walk->vma->vm_end, walk)) {
> > > -                     walk->vma = walk->vma->vm_next;
> > > +                     walk->vma = find_vma(walk->mm, walk->vma->vm_end);
> > >                       continue;
> > >               }
> > >
> > > @@ -4062,7 +4062,7 @@ static void walk_mm(struct lruvec *lruve
> > >               /* the caller might be holding the lock for write */
> > >               if (mmap_read_trylock(mm)) {
> > >                       unsigned long start = walk->next_addr;
> > > -                     unsigned long end = mm->highest_vm_end;
> > > +                     unsigned long end = TASK_SIZE;
> > >
> > >                       err = walk_page_range(mm, start, end, &mm_walk_ops, walk);

View attachment "0001-mm-vmscan-Use-VMA_ITERATOR-in-get_next_vma.patch" of type "text/x-diff" (1934 bytes)