linux-kernel - Re: [PATCH -next] arch_topology: Fix cache attributes detection in the CPU hotplug path

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Date:   Fri, 15 Jul 2022 10:11:21 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Conor.Dooley@...rochip.com
Cc:     linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        ionela.voinescu@....com, pierre.gondois@....com,
        linux-arm-kernel@...ts.infradead.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH -next] arch_topology: Fix cache attributes detection in
 the CPU hotplug path

On Thu, Jul 14, 2022 at 04:10:36PM +0000, Conor.Dooley@...rochip.com wrote:
> On 14/07/2022 17:00, Sudeep Holla wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On Thu, Jul 14, 2022 at 03:27:09PM +0000, Conor.Dooley@...rochip.com wrote:
> >> On 14/07/2022 16:01, Sudeep Holla wrote:
> >>>
> >>> Interesting, need to check if it is not in atomic context on arm64.
> >>> Wonder if some configs are disabled and making this bug hidden. Let me
> >>> check.
> >>>
> > 
> > OK, it turns I didn't have necessary config options enabled. Enabling
> > them, I did see the BUG splat and changing allocation to GFP_ATOMIC
> > fixed the same. Can you try that please so that you can test if other
> > things are fine.
> > 
> >>> One possible solution is to add GFP_ATOMIC to the allocation but I want
> >>> to make sure if it is legal to be in atomic context when calling
> >>> update_siblings_masks.
> >>>
> > 
> > So I take is as legal and needs to be fixed to push my patch.
> > 
> 
> With the GFP_ATOMIC, behaviour is the same as before for me.
>

So you still get -ENOMEM failure on your platform. It is fine, just that
I am bit curious to know why as it succeeds at device_initcall later.
I was hoping this might fix your memory allocation failure.

> Therefore, with the following diff & for RISC-V/DT:
> 
> Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
>

Thanks !

-- 
Regards,
Sudeep