From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8E7248A8BB for ; Wed, 19 Aug 2026 16:37:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787157426; cv=none; b=cmy0AroJZCxgDBUAO8jxmcNXsk1C/Bz4NWo1M97d2BzNn6+frffr9mlEJr9RC91Yg95uTiQp3cfF+NzQJpMXOmj+EgqWatichyyLKgiwTcl7DYlAWtQFrb35DQ8wDrHeOJaVtHT08EVsBPcAySubkJ4N7H66jLg6rOowbOu4bOQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787157426; c=relaxed/simple; bh=pr/mOrKNrihbvxZpK9+jrONIYord+BLta6/NkM4PkzQ=; h=MIME-Version:Date:From:To:Cc:Message-Id:In-Reply-To:References: Subject:Content-Type; b=IEC2xxYvmCfh8yO3SAq3qrezS3upYVJDPmplNpEAasBLLchRccFNDR3O21Nmg9j1iU9BmF2Nv5gPOS54fSmftmuHaNkYBep4WL3MAewRV5U3awg0RGtmLXEakqBmYqqhfWIodQ+EGMZcltOOul4M06Aon9BipiDhCy3Dl5EhXEA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gZNNO9kn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gZNNO9kn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 023161F000E9 for ; Wed, 19 Aug 2026 16:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787157425; bh=QsHEuqcdf3ru8nPwtUEXSBpm0W4HyNiSw2503P8ARO0=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=gZNNO9knt/IoPYcaBewn5z/dBrZWDxjSpCRAH0E/jnKKf5zwgPzZQp6jkGtMrsgP9 sGdfG2zfHaizAMfGO+760bkER1ybyTXWDXqoICkyoPev7mnmmlaILeEUyyyYBwbd/V 0CbAYGwHtGnM5m++Pg0q6+HP+eRo0gidxBQEPOU4NpVF/P3fZWirTefPKCvg+/xa6I q1GWF3Q2nCQhjFKBIviBcxRYTDePGjC1HMKk+20oobf27L77JJJ4nF6o+j1EoAT7dM hnShgcTnZSg0ejmd80JOL+99252chZfwQje6ffKnvQg9kJc2/4Kmct/lD4XSVm866q V6HZh+Y6wOmzQ== Received: from ams-compute-02.internal (ams-compute-02.internal [10.64.2.62]) by mailfauth.ams.internal (Postfix) with ESMTP id 7BC3B1980045; Wed, 19 Aug 2026 12:37:03 -0400 (EDT) Received: from ams-imap-11 ([10.64.2.31]) by ams-compute-02.internal (MEProxy); Wed, 19 Aug 2026 12:37:03 -0400 X-ME-Sender: X-ME-Proxy-Cause: dmFkZTEzE8aUVDxTong4hnJ8VtE8fbJv1fo/B8hPJ4CFDN4gIvKOB1NJX9QKNYv9Rbu5RZ eL2U24IvdfMCHAmV9/P0i6/hAjxED07ZY2b8lyCwTfAHrNcCy4lQy1xFOIXubynYm7EeDx 2nlK6MaafCQhEsDxZoHeHJYhYjUyWhBTndcE8ZdUGhniMga51nvraSBabg6TmhwBvQlvZj PMmfBtSfUbWyjK/G1HcIUdXqmrGaCfgBDYC+0Wk3DU73t83bPlwwXEAYrbxliS/IVx/zoO qCttFHVkH+YMxXACmwWtdSFTrpTOrx0yTqf1qTBP1NOl34AiX3WDRp5/QOwBSj6K+dkSad i+at6FvHlacWjaFTa4YCzIAcumiI7ggi21l9zGrrNqT0ZyxzIgd46aDv22Z/9jyyX0EGH6 ru4EYG6SiErKJNyRQn0stwtAVk3ch4MvCmBrcmryhwRX/uFMwNRGrNVSf38vyEntgo4Qe2 XVRKh3QrY5eiLsONrqMfXQYJj6djEk5tquuZEvB5vfJI5XAOrtTANIYnpg35Ic0fQ4zhHu zYg2jG+0xUQ05wv1PRtFACcv4OA1cQyleeYn5Ebt3p1GR53f8tOgl6F0upMQdpyRouHZDy +pUeBVSF28qiPD8A0rvk8Yx2D07xHmkgZjXMuBQsYwhTX++giHcyeWeFVMnw X-ME-Proxy: Feedback-ID: ice86485a:Fastmail Received: by mailuser.ams.internal (Postfix, from userid 501) id 965E0F80071; Wed, 19 Aug 2026 12:37:01 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Wed, 19 Aug 2026 19:36:40 +0300 From: "Ard Biesheuvel" To: "Anisse Astier" Cc: linux-efi@vger.kernel.org, x86@kernel.org, stable@vger.kernel.org, "Ravi Bangoria" Message-Id: In-Reply-To: References: <20260818141150.905336-1-ardb@kernel.org> Subject: Re: [PATCH] efivarfs: Rate limit statfs() handler Content-Type: text/plain Content-Transfer-Encoding: 7bit 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: > Thanks!