linux-kernel - Re: [PATCH v5] pseries: prevent free CPU ids to be reused on another node

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Message-ID: <1bfe14e7-0742-fcae-72f7-de7874232ee1@linux.ibm.com>
Date:   Tue, 3 Aug 2021 19:37:50 +0200
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     Nathan Lynch <nathanl@...ux.ibm.com>, mpe@...erman.id.au,
        benh@...nel.crashing.org, paulus@...ba.org
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] pseries: prevent free CPU ids to be reused on another
 node

Le 03/08/2021 à 18:54, Nathan Lynch a écrit :
> Laurent Dufour <ldufour@...ux.ibm.com> writes:
>> V5:
>>   - Rework code structure
>>   - Reintroduce the capability to reuse other node's ids.
> 
> OK. While I preferred v4, where we would fail an add rather than allow
> CPU IDs to appear to "travel" between nodes, this change is a net
> improvement.
> 
> Reviewed-by: Nathan Lynch <nathanl@...ux.ibm.com>
> 

Thanks Nathan,

Regarding the reuse of other nodes free CPU ids, with this patch the kernel does 
it best to prevent that. Instead of failing adding new CPUs, I think it's better 
to reuse free CPU ids of other nodes, otherwise, only a reboot would allow the 
CPU adding operation to succeed.

Laurent.