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From: Thomas Gleixner <tglx@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@efficios.com>, =?utf-8?Q?Andr=C3=A8?= Almeida
 <andrealmeid@igalia.com>,
 Sebastian Andrzej Siewior <bigeasy@linutronix.de>, Carlos O'Donell
 <carlos@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Florian Weimer
 <fweimer@redhat.com>, Rich Felker <dalias@aerifal.cx>, Torvald Riegel
 <triegel@redhat.com>, Darren Hart <dvhart@infradead.org>, Ingo Molnar
 <mingo@kernel.org>, Davidlohr Bueso <dave@stgolabs.net>, Arnd Bergmann
 <arnd@arndb.de>, "Liam R . Howlett" <Liam.Howlett@oracle.com>, Uros Bizjak
 <ubizjak@gmail.com>, Thomas =?utf-8?Q?Wei=C3=9Fschuh?=
 <linux@weissschuh.net>
Subject: Re: [patch V3 06/14] x86: Select ARCH_MEMORY_ORDER_TOS
In-Reply-To: <acp71dXQLRc27mUV@J2N7QTR9R3>
References: <20260330114212.927686587@kernel.org>
 <20260330120117.467037069@kernel.org> <acp71dXQLRc27mUV@J2N7QTR9R3>
Date: Mon, 30 Mar 2026 21:48:50 +0200
Message-ID: <87mrzp9jz1.ffs@tglx>
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On Mon, Mar 30 2026 at 14:34, Mark Rutland wrote:
> On Mon, Mar 30, 2026 at 02:02:31PM +0200, Thomas Gleixner wrote:
>> The generic unsafe_atomic_store_release_user() implementation does:
>>=20
>>     if (!IS_ENABLED(CONFIG_ARCH_MEMORY_ORDER_TOS))
>>         smp_mb();
>>     unsafe_put_user();
>>=20
>> As x86 implements Total Store Order (TOS) which means stores imply relea=
se,
>> select ARCH_MEMORY_ORDER_TOS to avoid the unnecessary smp_mb().
>>=20
>> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
>> Reviewed-by: Andr=C3=A9 Almeida <andrealmeid@igalia.com>
>> ---
>> V3: Rename to TOS - Peter
>
> As on the last patch, shouldn't that be TSO?

Duh. Yes. My dyslexia seems to get worse.