From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
To: Suren Baghdasaryan <surenb@google.com>,
"Liam R . Howlett" <liam@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>, Jann Horn <jannh@google.com>,
Michal Hocko <mhocko@suse.com>,
Shakeel Butt <shakeel.butt@linux.dev>,
Pedro Falcato <pfalcato@suse.de>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: prevent VMA generation reuse from skipping readers
Date: Thu, 15 Oct 2026 19:13:50 +0100 [thread overview]
Message-ID: <atEXg_B9_Hy9CEbN@gremlin> (raw)
In-Reply-To: <atD8jesRoc38xF0J@gremlin>
-schlopper.
On Thu, Oct 15, 2026 at 05:28:00PM +0100, Lorenzo Stoakes (ARM) wrote:
> On Thu, Oct 15, 2026 at 11:37:35PM +0900, <schlopper> wrote:
> > Both values are 32-bit. After 2^31 complete mmap write-lock acquisitions,
> > an old VMA stamp can alias the live odd generation. vma_start_write() then
> > returns without waiting for an existing reader.
>
> This is really unclear, I guess, as before, a member of the core team (likely
> me) will assess this to see if there's anything actually valid here.
OK I've assessed it, it's at least theoretically possible (Liam, wisely, raised
this before and we all, unwisely, dismissed it so, humble pie time :)
I am working on a patch. It's not necessary to add a new field to VMAs.
Will send out in a little bit.
--
Cheers, Lorenzo
prev parent reply other threads:[~2026-10-15 18:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-15 14:37 [PATCH] mm: prevent VMA generation reuse from skipping readers Daehyeon Ko
2026-10-15 16:28 ` Lorenzo Stoakes (ARM)
2026-10-15 18:13 ` Lorenzo Stoakes (ARM) [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=atEXg_B9_Hy9CEbN@gremlin \
--to=ljs@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=david@kernel.org \
--cc=jannh@google.com \
--cc=liam@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=pfalcato@suse.de \
--cc=rppt@kernel.org \
--cc=shakeel.butt@linux.dev \
--cc=surenb@google.com \
--cc=vbabka@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox