linux-kernel - Re: [PATCH v1 05/11] mm: convert VM_PFNMAP tracking to pfnmap_track() + pfnmap

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: <CAJuCfpEtnBrAkSV-6PDv4Au5gs02vWYeMNHo3OxZb8NB0sy8cw@mail.gmail.com>
Date: Mon, 28 Apr 2025 12:57:02 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: David Hildenbrand <david@...hat.com>, Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, x86@...nel.org, intel-gfx@...ts.freedesktop.org, 
	dri-devel@...ts.freedesktop.org, linux-trace-kernel@...r.kernel.org, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Andy Lutomirski <luto@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>, 
	Jani Nikula <jani.nikula@...ux.intel.com>, 
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>, 
	Tvrtko Ursulin <tursulin@...ulin.net>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Andrew Morton <akpm@...ux-foundation.org>, 
	Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>, 
	Pedro Falcato <pfalcato@...e.de>
Subject: Re: [PATCH v1 05/11] mm: convert VM_PFNMAP tracking to pfnmap_track()
 + pfnmap_untrack()

On Mon, Apr 28, 2025 at 12:37 PM Lorenzo Stoakes
<lorenzo.stoakes@...cle.com> wrote:
>
> On Mon, Apr 28, 2025 at 07:23:18PM +0200, David Hildenbrand wrote:
> > On 28.04.25 18:24, Peter Xu wrote:
> > > On Mon, Apr 28, 2025 at 06:16:21PM +0200, David Hildenbrand wrote:
> > > > > Probably due to what config you have.  E.g., when I'm looking mine it's
> > > > > much bigger and already consuming 256B, but it's because I enabled more
> > > > > things (userfaultfd, lockdep, etc.).
> > > >
> > > > Note that I enabled everything that you would expect on a production system
> > > > (incld. userfaultfd, mempolicy, per-vma locks), so I didn't enable lockep.
> > >
> > > I still doubt whether you at least enabled userfaultfd, e.g., your previous
> > > paste has:
> > >
> > >    struct vm_userfaultfd_ctx  vm_userfaultfd_ctx;   /*   176     0 */
> > >
> > > Not something that matters.. but just in case you didn't use the expected
> > > config file you wanted to use..
> >
> > You're absolutely right. I only briefly rechecked for this purpose here on
> > my notebook, and only looked for the existence of members, not expecting
> > that we have confusing stuff like vm_userfaultfd_ctx.
> >
> > I checked again and the size stays at 192 with allyesconfig and then
> > disabling debug options.
>
> I think a reasonable case is everything on, except CONFIG_DEBUG_LOCK_ALLOC and I
> don't care about nommu.

I think it's safe to assume that production systems would disable
lockdep due to the performance overhead. At least that's what we do on
Android - enable it on development branches but disable in production.

>
> So:
>
> CONFIG_PER_VMA_LOCK
> CONFIG_SWAP
> CONFIG_MMU (exclude the nommu vm_region field)
> CONFIG_NUMA
> CONFIG_NUMA_BALANCING
> CONFIG_PER_VMA_LOCK
> CONFIG_ANON_VMA_NAME
> __HAVE_PFNMAP_TRACKING
>
> So to be clear - allyesconfig w/o debug gives us this yes? And we don't add a
> cache line? In which case all good :)
>
>
> >
> > --
> > Cheers,
> >
> > David / dhildenb
> >
>