From: Yosry Ahmed <yosryahmed@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH v3 0/3] x86/mm: LAM fixups and cleanups
Date: Tue, 2 Jul 2024 10:39:03 -0700 [thread overview]
Message-ID: <CAJD7tkb7=sBdxXTmcqxe3+UWsTT7R6-rKGBhkEfgEAdTY+5jCw@mail.gmail.com> (raw)
In-Reply-To: <20240702103628.61879ef17b9b01305515c634@linux-foundation.org>
On Tue, Jul 2, 2024 at 10:36 AM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue, 2 Jul 2024 13:21:36 +0000 Yosry Ahmed <yosryahmed@google.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?
I don't think it would be common. The bug only happens on new hardware
supporting LAM, and it happens in a specific scenario where a
userspace task enables LAM while a kthread is using (borrowing) its
mm_struct on another CPU.
So it is possible but I certainly wouldn't call it common or easily triggerable.
next prev parent reply other threads:[~2024-07-02 17:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-02 13:21 Yosry Ahmed
2024-07-02 13:21 ` [RESEND PATCH v3 1/3] x86/mm: Use IPIs to synchronize LAM enablement Yosry Ahmed
2024-07-02 18:58 ` Borislav Petkov
2024-07-02 19:00 ` Yosry Ahmed
2024-07-02 13:21 ` [RESEND PATCH v3 2/3] x86/mm: Fix LAM inconsistency during context switch Yosry Ahmed
2024-07-02 13:21 ` [RESEND PATCH v3 3/3] x86/mm: Cleanup prctl_enable_tagged_addr() nr_bits error checking Yosry Ahmed
2024-07-02 17:36 ` [RESEND PATCH v3 0/3] x86/mm: LAM fixups and cleanups Andrew Morton
2024-07-02 17:39 ` Yosry Ahmed [this message]
2024-07-02 18:35 ` Andrew Morton
2024-07-02 18:38 ` Dave Hansen
2024-07-02 18:55 ` Yosry Ahmed
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