linux-kernel - Re: [PATCH v22 1/4] mm: add MAP_DROPPABLE for designating always lazily freeable mappings

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: <443146f4-9db8-4a19-91f1-b6822fad8ce8@redhat.com>
Date: Thu, 11 Jul 2024 20:56:21 +0200
From: David Hildenbrand <david@...hat.com>
To: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
 linux-kernel@...r.kernel.org, patches@...ts.linux.dev, tglx@...utronix.de,
 linux-crypto@...r.kernel.org, linux-api@...r.kernel.org, x86@...nel.org,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Adhemerval Zanella Netto <adhemerval.zanella@...aro.org>,
 Carlos O'Donell <carlos@...hat.com>, Florian Weimer <fweimer@...hat.com>,
 Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
 Christian Brauner <brauner@...nel.org>,
 David Hildenbrand <dhildenb@...hat.com>, linux-mm@...ck.org
Subject: Re: [PATCH v22 1/4] mm: add MAP_DROPPABLE for designating always
 lazily freeable mappings

On 11.07.24 20:54, Jason A. Donenfeld wrote:
> On Thu, Jul 11, 2024 at 08:24:07PM +0200, David Hildenbrand wrote:
>>> And PG_large_rmappable seems to only be used for hugetlb branches.
>>
>> It should be set for THP/large folios.
> 
> And it's tested too, apparently.
> 
> Okay, well, how disappointing is this below? Because I'm running out of
> tricks for flag reuse.
> 
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index b9e914e1face..c1ea49a7f198 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -110,6 +110,7 @@ enum pageflags {
>   	PG_workingset,
>   	PG_error,
>   	PG_owner_priv_1,	/* Owner use. If pagecache, fs may use*/
> +	PG_owner_priv_2,

Oh no, no new page flags please :)

Maybe just follow what Linux suggested: pass vma to pte_dirty() and 
always return false for these special VMAs.

-- 
Cheers,

David / dhildenb