Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
Date:   Mon, 16 Oct 2023 16:40:58 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Yazen Ghannam <yazen.ghannam@amd.com>,
        "Sironi, Filippo" <sironi@amazon.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "tony.luck@intel.com" <tony.luck@intel.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "x86@kernel.org" <x86@kernel.org>, "hpa@zytor.com" <hpa@zytor.com>,
        "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>
Subject: Re: [PATCH] x86/mce: Increase the size of the MCE pool from 2 to 8
 pages
Message-ID: <20231016144058.GEZS1LemcrhZvVrC15@fat_crate.local>
References: <20231011163320.79732-1-sironi@amazon.de>
 <afaef377-25e0-49f6-a99f-3e5bd4b44f87@intel.com>
 <EDD08AA3-C404-4DB6-96BA-2B25519B2496@amazon.de>
 <6591377b-7911-444b-abf9-cfc978472d76@intel.com>
 <1c598798-5b28-4a17-bf86-042781808021@amd.com>
 <dd72296c-def6-4fb3-9984-348641cdb6a4@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <dd72296c-def6-4fb3-9984-348641cdb6a4@intel.com>
Precedence: bulk

On Mon, Oct 16, 2023 at 07:24:34AM -0700, Dave Hansen wrote:
> On 10/16/23 07:14, Yazen Ghannam wrote:
> > 1) Keep the current config size for boot time. 
> > 2) Add a kernel parameter
> > and/or sysfs file to allow users to request additional genpool capacity.
> > 3) Use gen_pool_add(), or whichever, to add the capacity based on user
> > input. Maybe this can be expanded later to be automatic. But I think it
> > simpler to start with explicit user input.
> 
> I guarantee virtually nobody will ever use an explicit kernel interface
> to bump the size up.  It'll be the same exact folks that recompile their
> kernels.
> 
> An automatic resizing one doesn't have to be fancy and only has to
> expand once:

Can we slow down here pls?

You expand once and then that stuck bit error increases its rate of MCEs
reported and all of a sudden that raised size is overflowed again.

Or, you add logic which thresholds duplicate errors similar to the cmci
storm logic we have.

*If* that is the case at all.

So can we analyze first what type of errors are reported and why they're
overflowing the pool before we do ad-hoc hackery?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette