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From: Thomas Gleixner <tglx@linutronix.de>
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To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, LKML
 <linux-kernel@vger.kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>, Peter Zijlstra <peterz@infradead.org>,
 "Paul E. McKenney" <paulmck@kernel.org>, Boqun Feng
 <boqun.feng@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Sean
 Christopherson <seanjc@google.com>, Wei Liu <wei.liu@kernel.org>, Dexuan
 Cui <decui@microsoft.com>, x86@kernel.org, Arnd Bergmann <arnd@arndb.de>,
 Heiko Carstens <hca@linux.ibm.com>, Christian Borntraeger
 <borntraeger@linux.ibm.com>, Sven Schnelle <svens@linux.ibm.com>, Huacai
 Chen <chenhuacai@kernel.org>, Paul Walmsley <paul.walmsley@sifive.com>,
 Palmer Dabbelt <palmer@dabbelt.com>
Subject: Re: [patch V2 23/37] rseq: Provide and use rseq_set_uids()
In-Reply-To: <878qix0wx4.ffs@tglx>
References: <20250823161326.635281786@linutronix.de>
 <20250823161654.741798449@linutronix.de>
 <e87fb53b-329b-44dc-a14e-e8c7a49d9adf@efficios.com> <878qix0wx4.ffs@tglx>
Date: Tue, 02 Sep 2025 18:33:47 +0200
Message-ID: <87qzwozudw.ffs@tglx>
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On Tue, Sep 02 2025 at 16:08, Thomas Gleixner wrote:
> On Tue, Aug 26 2025 at 10:52, Mathieu Desnoyers wrote:
>>> +
>>> +	/* Cache the new values */
>>> +	t->rseq_ids.cpu_cid = ids->cpu_cid;
>>
>> I may be missing something, but I think we're missing updates to
>> t->rseq_ids.mm_cid and we may want to keep track of t->rseq_ids.node_id
>> as well.
>
> Oops. I'm sure I had that mm_cid caching, but somehow dropped it. And
> again, no need to keep track of the node id. It's stable vs. CPU ID.

Correcting myself. You are missing that this caches the compound value
and not only the CPU id.