From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A266FC433FE for ; Sun, 7 Nov 2021 16:45:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 891A261076 for ; Sun, 7 Nov 2021 16:45:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235280AbhKGQsW (ORCPT ); Sun, 7 Nov 2021 11:48:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:47130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233677AbhKGQsU (ORCPT ); Sun, 7 Nov 2021 11:48:20 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 600716105A; Sun, 7 Nov 2021 16:45:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636303537; bh=ikEqkWoGV0ZZ05Cxs8H6ZUvViZmPvoGfggCdVVdXbo4=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=SDgq5+4oPQhSMUwCFFUf8R3og8CKaj6wDxgDXYeHlEXK0566GfNdtaT4gLwlChX4h uWcxDlXIIFGSuAgXYROWl6mR/GkEpv4j9vh1y2W4HIqpGuMtediBry2fH9wNHDzSag jB/eRAJFkl8JwrALWZsRbw/u4LjVxmMZx3HvS6XRlpDieTQO0O0LPA0uHQ5XuRKgRN T5fpHfZK0sOzW4uIXxj3I4T0SyZR4jY8iYX63hUJGtvpX+HRYPeDj5Zwtw//EvOkSC SAHcmh/LT6gcpCcpW0oMjqf+3xE04GqJ3EtjJONlQsId/0Tl7rIFSd01eMGecoi/ct V4theHKdNimlA== Message-ID: <6e51fdacc2c1d834258f00ad8cc268b8d782eca7.camel@kernel.org> Subject: Re: [PATCH] x86/sgx: Fix free page accounting From: Jarkko Sakkinen To: Reinette Chatre , dave.hansen@linux.intel.com, tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, linux-sgx@vger.kernel.org, x86@kernel.org Cc: seanjc@google.com, tony.luck@intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org Date: Sun, 07 Nov 2021 18:45:35 +0200 In-Reply-To: <373992d869cd356ce9e9afe43ef4934b70d604fd.1636049678.git.reinette.chatre@intel.com> References: <373992d869cd356ce9e9afe43ef4934b70d604fd.1636049678.git.reinette.chatre@intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.40.4-1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2021-11-04 at 11:28 -0700, Reinette Chatre wrote: > The consequence of sgx_nr_free_pages not being protected is that > its value may not accurately reflect the actual number of free > pages on the system, impacting the availability of free pages in > support of many flows. The problematic scenario is when the > reclaimer never runs because it believes there to be sufficient > free pages while any attempt to allocate a page fails because there > are no free pages available. The worst scenario observed was a > user space hang because of repeated page faults caused by > no free pages ever made available. Can you go in detail with the "concrete scenario" in the commit message? It does not have to describe all the possible scenarios but at least one sequence of events. /Jarkko