From: Dave Hansen <dave.hansen@intel.com>
To: Stephen Dolan <sdolan@janestreet.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org,
Eric Hagberg <ehagberg@janestreet.com>,
Nick Barnes <nbarnes@janestreet.com>
Subject: Re: x86/mm: Finishing off the fix for a should_flush_tlb race
Date: Fri, 10 Oct 2025 13:45:45 -0700 [thread overview]
Message-ID: <281e8018-5506-4a79-8775-e0de7e58b95f@intel.com> (raw)
In-Reply-To: <CAHDw0oGd0B4=uuv8NGqbUQ_ZVmSheU2bN70e4QhFXWvuAZdt2w@mail.gmail.com>
On 10/9/25 07:01, Stephen Dolan wrote:
> That way, either shootdown sees LOADED_MM_SWITCHING and sends an IPI, or
> switch_mm_irqs_off sees the updated tlb_gen. The problem in both cases
> is about the *before*-ness in switch_mm_irqs_off:
>
> - in the latest tree, there isn't enough fencing to enforce this
> ordering.
Stephen, thank you again for the stunningly great bug report!
I'll plan to stick the upstream fix into our x86/urgent pile early next
week.
> - in the stable kernel trees (6.1, 6.6, 6.12), the code is in the
> wrong order.
This fix also makes sense to me. It's a bummer that the stable fixes are
diverging, but I don't have a better idea. So:
Acked-by: Dave Hansen <dave.hansen@intel.com>
It would be best if you could just submit that patch directly to the
stable trees:
https://www.kernel.org/doc/Documentation/process/stable-kernel-rules.rst
after the equivalent upstream fix lands (even though it is a different
logical patch).
next prev parent reply other threads:[~2025-10-10 20:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-09 14:01 Stephen Dolan
2025-10-10 20:45 ` Dave Hansen [this message]
2026-02-17 15:12 ` Seth Forshee
2026-02-17 15:20 ` Seth Forshee
2026-02-17 17:21 ` Stephen Dolan
2026-02-18 19:43 ` Seth Forshee
2026-02-24 9:38 ` Stephen Dolan
2026-03-10 17:22 ` Greg Thelen
2026-03-12 21:06 ` Dave Hansen
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