linux-kernel - Re: [PATCH v2] Revert "x86/smp: Eliminate mwait_play_dead_cpuid

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Message-ID: <a72c38b2-c52f-446a-bf0f-2bae7d6021f8@intel.com>
Date: Thu, 29 May 2025 07:25:43 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>, x86 Maintainers <x86@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux PM <linux-pm@...r.kernel.org>,
 Len Brown <lenb@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
 Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
 "Gautham R. Shenoy" <gautham.shenoy@....com>, Ingo Molnar
 <mingo@...hat.com>, Todd Brandt <todd.e.brandt@...ux.intel.com>
Subject: Re: [PATCH v2] Revert "x86/smp: Eliminate
 mwait_play_dead_cpuid_hint()"

On 5/29/25 06:40, Rafael J. Wysocki wrote:
> This issue is hard to debug and potentially dangerous, so it needs to
> be addressed as soon as possible in a way that will work for 6.15.y,
> hence the revert.

Ugh.

I don't like the idea of reintroducing known buggy code. But the revert
does seem like the lesser of the two evils.

Seems like we should revert this for the time being and then try to fix
it properly again.

Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>