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From: Anisse Astier <anisse@astier.eu>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi@vger.kernel.org, x86@kernel.org,
	stable@vger.kernel.org, Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [PATCH] efivarfs: Rate limit statfs() handler
Date: Wed, 19 Aug 2026 18:29:35 +0200	[thread overview]
Message-ID: <aoXZ7xBT546YKdOY@kanto> (raw)
In-Reply-To: <20260818141150.905336-1-ardb@kernel.org>

Hi Ard,

I like the new approach, it's much simpler and easier to understand

On Tue, Aug 18, 2026 at 04:11:50PM +0200, Ard Biesheuvel wrote:
> Ravi reports that statfs() may be called by unprivileged users on the
> efivarfs mount point, which may result in a flood of calls to the
> QueryVariableInfo() runtime service. These calls are disproportionately
> costly on x86 systems where the variable store is backed by SMM, as each
> SMM entry requires a rendez-vous of all the CPUs.
> 
> So rate limit the calls to QueryVariableInfo() at twice per second, and

It's already a high-rate in performance sensitive environment. I'd have
gone higher at once per 10 seconds for example. But really, this is
minor, so please consider this:

Reviewed-by: <anisse@astier.eu>

Regards,

Anisse

  reply	other threads:[~2026-08-19 16:30 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-18 14:11 [PATCH] efivarfs: Rate limit statfs() handler Ard Biesheuvel
2026-08-19 16:29 ` Anisse Astier [this message]
2026-08-19 16:36   ` Ard Biesheuvel

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