From: "Ard Biesheuvel" <ardb@kernel.org>
To: "Anisse Astier" <anisse@astier.eu>
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 19:36:40 +0300 [thread overview]
Message-ID: <e4153579-37a2-424b-b96b-eb0f1d8085be@app.fastmail.com> (raw)
In-Reply-To: <aoXZ7xBT546YKdOY@kanto>
On Wed, 19 Aug 2026, at 19:29, Anisse Astier wrote:
> 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>
>
Thanks!
prev parent reply other threads:[~2026-08-19 16:37 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
2026-08-19 16:36 ` Ard Biesheuvel [this message]
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