linux-kernel - Re: [PATCH 2/2] x86/MCE: Add command line option to extend MCE Records pool

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Message-ID: <34b19db5-bd72-457c-9b6a-c2089f6be83c@amd.com>
Date: Mon, 12 Feb 2024 14:43:28 -0500
From: Yazen Ghannam <yazen.ghannam@....com>
To: "Luck, Tony" <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>,
 "Naik, Avadhut" <avadnaik@....com>
Cc: yazen.ghannam@....com, "Mehta, Sohil" <sohil.mehta@...el.com>,
 "x86@...nel.org" <x86@...nel.org>,
 "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 Avadhut Naik <avadhut.naik@....com>
Subject: Re: [PATCH 2/2] x86/MCE: Add command line option to extend MCE
 Records pool

On 2/12/2024 1:58 PM, Luck, Tony wrote:
>> I need to look more at the genpool code, but I thought I'd ask too.
> 
> Yazen,
> 
> gen_pool_add_owner() is the code that adds an extra chunk to an existing genpool.
> 
> This bit doesn't look obviously safe against a #MC at the wrong moment in the middle of
> the list_add_rcu()
> 
>          spin_lock(&pool->lock);
>          list_add_rcu(&chunk->next_chunk, &pool->chunks);
>          spin_unlock(&pool->lock);
> 

Thanks Tony.

So the concern is not about traversal, but rather that the #MC can break the
list_add_rcu(). Is this correct?


Thanks,
Yazen