linux-kernel - Re: [PATCH mm-new v5 5/5] mm: khugepaged: set to next mm direct when mm has MMF_DISABLE_THP

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Message-ID: <CACZaFFMJkjoQP=w_nCJWicvTXT_9Tm1TYcYYVUiS=kbVmwQ_uQ@mail.gmail.com>
Date: Fri, 23 Jan 2026 23:32:17 +0800
From: Vernon Yang <vernon2gm@...il.com>
To: Dev Jain <dev.jain@....com>
Cc: akpm@...ux-foundation.org, david@...nel.org, lorenzo.stoakes@...cle.com, 
	ziy@...dia.com, baohua@...nel.org, lance.yang@...ux.dev, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, Vernon Yang <yanglincheng@...inos.cn>
Subject: Re: [PATCH mm-new v5 5/5] mm: khugepaged: set to next mm direct when
 mm has MMF_DISABLE_THP_COMPLETELY

On Fri, Jan 23, 2026 at 8:40 PM Dev Jain <dev.jain@....com> wrote:
>
> On 23/01/26 1:52 pm, Vernon Yang wrote:
> > From: Vernon Yang <yanglincheng@...inos.cn>
> >
> > When an mm with the MMF_DISABLE_THP_COMPLETELY flag is detected during
> > scanning, directly set khugepaged_scan.mm_slot to the next mm_slot,
> > reduce redundant operation.
> >
> > Without this patch, entering khugepaged_scan_mm_slot() next time, we
> > will set khugepaged_scan.mm_slot to the next mm_slot.
> >
> > With this patch, we will directly set khugepaged_scan.mm_slot to the
> > next mm_slot.
> >
> > Signed-off-by: Vernon Yang <yanglincheng@...inos.cn>
> > Acked-by: David Hildenbrand (Red Hat) <david@...nel.org>
> > Reviewed-by: Lance Yang <lance.yang@...ux.dev>
> > ---
> >  mm/khugepaged.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index be1c09842ea2..1dc19c1b1f97 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -2558,7 +2558,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, enum scan_result
> >        * Release the current mm_slot if this mm is about to die, or
> >        * if we scanned all vmas of this mm.
> >        */
>
> Need to update comment: "...or THP got disabled".

LGTM, I will update comment in the next version. Thanks!

> Reviewed-by: Dev Jain <dev.jain@....com>
>
> > -     if (hpage_collapse_test_exit(mm) || !vma) {
> > +     if (hpage_collapse_test_exit_or_disable(mm) || !vma) {
> >               /*
> >                * Make sure that if mm_users is reaching zero while
> >                * khugepaged runs here, khugepaged_exit will find