linux-kernel - Re: [PATCH v8 mm-new 01/12] mm: thp: remove disabled task from khugepaged_mm

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] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALOAHbD8tup+4DbQ6tMzDxk=XkhW1t6B2L8+k8nP-1wg2zoXqA@mail.gmail.com>
Date: Sun, 28 Sep 2025 10:21:37 +0800
From: Yafang Shao <laoar.shao@...il.com>
To: Usama Arif <usamaarif642@...il.com>
Cc: akpm@...ux-foundation.org, david@...hat.com, ziy@...dia.com, 
	baolin.wang@...ux.alibaba.com, lorenzo.stoakes@...cle.com, 
	Liam.Howlett@...cle.com, npache@...hat.com, ryan.roberts@....com, 
	dev.jain@....com, hannes@...xchg.org, gutierrez.asier@...wei-partners.com, 
	willy@...radead.org, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	ameryhung@...il.com, rientjes@...gle.com, corbet@....net, 21cnbao@...il.com, 
	shakeel.butt@...ux.dev, tj@...nel.org, lance.yang@...ux.dev, 
	bpf@...r.kernel.org, linux-mm@...ck.org, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 mm-new 01/12] mm: thp: remove disabled task from khugepaged_mm_slot

On Fri, Sep 26, 2025 at 10:11 PM Usama Arif <usamaarif642@...il.com> wrote:
>
>
>
> On 26/09/2025 10:33, Yafang Shao wrote:
> > Since a task with MMF_DISABLE_THP_COMPLETELY cannot use THP, remove it from
> > the khugepaged_mm_slot to stop khugepaged from processing it.
> >
> > After this change, the following semantic relationship always holds:
> >
> >   MMF_VM_HUGEPAGE is set     == task is in khugepaged mm_slot
> >   MMF_VM_HUGEPAGE is not set == task is not in khugepaged mm_slot
> >
> > Signed-off-by: Yafang Shao <laoar.shao@...il.com>
> > Acked-by: Lance Yang <lance.yang@...ux.dev>
> > ---
> >  include/linux/khugepaged.h |  4 ++++
> >  kernel/sys.c               |  7 ++++--
> >  mm/khugepaged.c            | 49 ++++++++++++++++++++------------------
> >  3 files changed, 35 insertions(+), 25 deletions(-)
> >
>
>
> Hi Yafang,
>
> Thanks for the patch! Sorry wasnt able to review the previous revisions.
>
> I think it would be good to separate this patch out of the series?

right. This commit is independent of this series. I will send it seperately.

> It would make the review of this series shorter and this patch can be merged independently.
>
> In the commit message, we also need to write explicitly that when prctl
> PR_SET_THP_DISABLE is cleared, the mm is added back for khugepaged to consider.

ack.

>
> Could you also mention in the commit message why the BUG was turned into WARN?
>

I believe we should replace VM_BUG_ON_MM() with VM_WARN_ON_MM() [0]. A
warning is sufficient for debugging in this context.

[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/deprecated.rst#n32

-- 
Regards
Yafang