linux-kernel - Re: [RESEND PATCH v3 0/3] x86/mm: LAM fixups and cleanups

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Message-Id: <20240702103628.61879ef17b9b01305515c634@linux-foundation.org>
Date: Tue, 2 Jul 2024 10:36:28 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Yosry Ahmed <yosryahmed@...gle.com>
Cc: x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar
 <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
 <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, Andy
 Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
 "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Rick Edgecombe
 <rick.p.edgecombe@...el.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v3 0/3] x86/mm: LAM fixups and cleanups

On Tue,  2 Jul 2024 13:21:36 +0000 Yosry Ahmed <yosryahmed@...gle.com> wrote:

> This series has fixups and cleanups for LAM. Most importantly, patch 1
> fixes a sycnhronization issue that may cause crashes of userspace
> applications. This is a resend of v3, rebased on top of v6.10-rc6.

"Crashes of userspace applications" is bad.  Yet the patchset has been
floating about for four months.

It's unclear (to me) how serious this is.  Can you please explain how
common this is, what the userspace application needs to do to trigger
this, etc?