linux-kernel - Re: [PATCH v8 14/15] khugepaged: add per-order mTHP khugepaged stats

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <CAA1CXcA9-JzToPQM4X9qB3sdXBYs3n9Sx4DWyM2i3qFtvu6w0g@mail.gmail.com>
Date: Thu, 10 Jul 2025 23:19:20 -0600
From: Nico Pache <npache@...hat.com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: linux-mm@...ck.org, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
	david@...hat.com, ziy@...dia.com, lorenzo.stoakes@...cle.com, 
	Liam.Howlett@...cle.com, ryan.roberts@....com, dev.jain@....com, 
	corbet@....net, rostedt@...dmis.org, mhiramat@...nel.org, 
	mathieu.desnoyers@...icios.com, akpm@...ux-foundation.org, baohua@...nel.org, 
	willy@...radead.org, peterx@...hat.com, wangkefeng.wang@...wei.com, 
	usamaarif642@...il.com, sunnanyong@...wei.com, vishal.moola@...il.com, 
	thomas.hellstrom@...ux.intel.com, yang@...amperecomputing.com, 
	kirill.shutemov@...ux.intel.com, aarcange@...hat.com, raquini@...hat.com, 
	anshuman.khandual@....com, catalin.marinas@....com, tiwai@...e.de, 
	will@...nel.org, dave.hansen@...ux.intel.com, jack@...e.cz, cl@...two.org, 
	jglisse@...gle.com, surenb@...gle.com, zokeefe@...gle.com, hannes@...xchg.org, 
	rientjes@...gle.com, mhocko@...e.com, rdunlap@...radead.org
Subject: Re: [PATCH v8 14/15] khugepaged: add per-order mTHP khugepaged stats

On Tue, Jul 8, 2025 at 12:10 AM Baolin Wang
<baolin.wang@...ux.alibaba.com> wrote:
>
>
>
> On 2025/7/2 13:57, Nico Pache wrote:
> > With mTHP support inplace, let add the per-order mTHP stats for
> > exceeding NONE, SWAP, and SHARED.
> >
> > Signed-off-by: Nico Pache <npache@...hat.com>
> > ---
> >   include/linux/huge_mm.h |  3 +++
> >   mm/huge_memory.c        |  7 +++++++
> >   mm/khugepaged.c         | 15 ++++++++++++---
> >   3 files changed, 22 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> > index a6ea89fdaee6..6034b4c9dae5 100644
> > --- a/include/linux/huge_mm.h
> > +++ b/include/linux/huge_mm.h
> > @@ -141,6 +141,9 @@ enum mthp_stat_item {
> >       MTHP_STAT_SPLIT_DEFERRED,
> >       MTHP_STAT_NR_ANON,
> >       MTHP_STAT_NR_ANON_PARTIALLY_MAPPED,
> > +     MTHP_STAT_COLLAPSE_EXCEED_SWAP,
>
> This stat seems never used.
Ah good catch, I somehow dropped that piece on the V5->v6/7
>
> > +     MTHP_STAT_COLLAPSE_EXCEED_NONE,
> > +     MTHP_STAT_COLLAPSE_EXCEED_SHARED,
> >       __MTHP_STAT_COUNT
> >   };
>
> Please also update the 'Documentation/admin-guide/mm/transhuge.rst' for
> these new statistics.
Will do thanks :)
>
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index 69777a35e722..3eb1c34be601 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -632,6 +632,10 @@ DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
> >   DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
> >   DEFINE_MTHP_STAT_ATTR(nr_anon, MTHP_STAT_NR_ANON);
> >   DEFINE_MTHP_STAT_ATTR(nr_anon_partially_mapped, MTHP_STAT_NR_ANON_PARTIALLY_MAPPED);
> > +DEFINE_MTHP_STAT_ATTR(collapse_exceed_swap_pte, MTHP_STAT_COLLAPSE_EXCEED_SWAP);
> > +DEFINE_MTHP_STAT_ATTR(collapse_exceed_none_pte, MTHP_STAT_COLLAPSE_EXCEED_NONE);
> > +DEFINE_MTHP_STAT_ATTR(collapse_exceed_shared_pte, MTHP_STAT_COLLAPSE_EXCEED_SHARED);
> > +
> >
> >   static struct attribute *anon_stats_attrs[] = {
> >       &anon_fault_alloc_attr.attr,
> > @@ -648,6 +652,9 @@ static struct attribute *anon_stats_attrs[] = {
> >       &split_deferred_attr.attr,
> >       &nr_anon_attr.attr,
> >       &nr_anon_partially_mapped_attr.attr,
> > +     &collapse_exceed_swap_pte_attr.attr,
> > +     &collapse_exceed_none_pte_attr.attr,
> > +     &collapse_exceed_shared_pte_attr.attr,
> >       NULL,
> >   };
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index 2c0962637c34..636b84bf1ca1 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -594,7 +594,10 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> >                               continue;
> >                       } else {
> >                               result = SCAN_EXCEED_NONE_PTE;
> > -                             count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
> > +                             if (order == HPAGE_PMD_ORDER)
> > +                                     count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
> > +                             else
> > +                                     count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_NONE);
> >                               goto out;
> >                       }
> >               }
> > @@ -623,8 +626,14 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> >               /* See khugepaged_scan_pmd(). */
> >               if (folio_maybe_mapped_shared(folio)) {
> >                       ++shared;
> > -                     if (order != HPAGE_PMD_ORDER || (cc->is_khugepaged &&
> > -                         shared > khugepaged_max_ptes_shared)) {
> > +                     if (order != HPAGE_PMD_ORDER) {
> > +                             result = SCAN_EXCEED_SHARED_PTE;
> > +                             count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_SHARED);
> > +                             goto out;
> > +                     }
> > +
> > +                     if (cc->is_khugepaged &&
> > +                             shared > khugepaged_max_ptes_shared) {
> >                               result = SCAN_EXCEED_SHARED_PTE;
> >                               count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
> >                               goto out;
>