linux-kernel - Re: [PATCH v4 2/3] mm/rmap: integrate PMD-mapped folio splitting into pagewalk loop

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Message-ID: <CAK1f24=rWdgscbDa6pMqOmTEDOHVLo5NQ=7jOo9TdyJRXahHZg@mail.gmail.com>
Date: Tue, 7 May 2024 16:38:07 +0800
From: Lance Yang <ioworker0@...il.com>
To: David Hildenbrand <david@...hat.com>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>, akpm@...ux-foundation.org, 
	willy@...radead.org, sj@...nel.org, maskray@...gle.com, ziy@...dia.com, 
	ryan.roberts@....com, 21cnbao@...il.com, mhocko@...e.com, 
	fengwei.yin@...el.com, zokeefe@...gle.com, shy828301@...il.com, 
	xiehuan09@...il.com, libang.li@...group.com, wangkefeng.wang@...wei.com, 
	songmuchun@...edance.com, peterx@...hat.com, minchan@...nel.org, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] mm/rmap: integrate PMD-mapped folio splitting into
 pagewalk loop

Hey David,

Thanks for reaching out!

On Tue, May 7, 2024 at 4:17 PM David Hildenbrand <david@...hat.com> wrote:
>
> >>>
> >>> +             if (!pvmw.pte && (flags & TTU_SPLIT_HUGE_PMD)) {
> >>> +                     /*
> >>> +                      * We temporarily have to drop the PTL and start once
> >>> +                      * again from that now-PTE-mapped page table.
> >>> +                      */
> >>> +                     split_huge_pmd_locked(vma, range.start, pvmw.pmd, false,
> >>> +                                           folio);
> >>> +                     pvmw.pmd = NULL;
> >>> +                     spin_unlock(pvmw.ptl);
> >>
> >> IMO, you should also make the 'pvmw.ptl = NULL;' after unlocking as
> >> page_vma_mapped_walk() did, in case some corner case met.
> >
> > Yep, I'll also set pvmw.ptl to NULL here if any corner cases arise.
> >
>
> This series already resides in mm-stable. I asked Andrew to remove it
> for now. If that doesn't work, we'll need fixup patches to address any
> review feedback.

I'll patiently wait Andrew's response, and then submit the next version or
fixup patches accordingly.

Thanks,
Lance

>
> --
> Cheers,
>
> David / dhildenb
>