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 X-Spam-Level: X-Spam-Status: No, score=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 693B6C433E0 for ; Tue, 26 Jan 2021 17:21:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F31C2083E for ; Tue, 26 Jan 2021 17:21:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728840AbhAZRUn (ORCPT ); Tue, 26 Jan 2021 12:20:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392971AbhAZQaz (ORCPT ); Tue, 26 Jan 2021 11:30:55 -0500 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAE9DC061574 for ; Tue, 26 Jan 2021 08:30:14 -0800 (PST) Received: by mail-pj1-x1035.google.com with SMTP id e9so2532264pjj.0 for ; Tue, 26 Jan 2021 08:30:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=PaCzCYCH4aX6Kv1jMmoIcCojESLo94WkAXAYpiqsmdk=; b=RGq1J9JqSlV5ElJQhgbRf54UqcTFczVkcyVGQuLoiue+YDzh+JSKx55lyZrvbEs+EL kUdM4CYnu+FMiisy6t0l+ULhDp8YDOJFJdbbs/Qsr6L+lgKyC4N/njPLagnNIv1KjUqN 79fW1VXUcxxlm1zc2wm84yNjalDPaHuHvKp9gTe+LecWcdur4CTFPa3TBAyRNASIWLpa jxZV2i2yeGez5sOkZy2611JJp1eWG2X/m95W80B71A4zCS2oI7q0C1JrO0gs4GngZMPG kB0OK7LP8WUkvV8QkfLFjYXXmKwbNNkC8X/iFP4GscoYsILs0edXrPDVsKF6/w1R9foU 06HA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=PaCzCYCH4aX6Kv1jMmoIcCojESLo94WkAXAYpiqsmdk=; b=XRjIG9dT1xtRsnfjasV6zwiY2LHMJh2P2C3HJ/JWU9eSw3xvtGn2IfBBU1k9L9B/CD ahr3REqL+G68fdgOMzRpCTupYtrb7EnWsLLc1vqEZAjTINXi6/xLgIhaeoRrMNmIAYLo HkizGUvAyGxrqD0rlMk96ibt2hcjNK1WtOWw73sNs8JpzIObQm40vW/8GgI116eonSdp JKNoFns1YFrBF+Kn8XbW9y1tk/MzzEzNLmknZU48S1PAWsGLkxh4QgojZsw0Gr1bSeN5 M4T8hcZafkiB9SivgXzcAGAIoT+Yo3wokrFu2gV8d2fynfsKndR/TWfaQXkQrscF22n8 QJPA== X-Gm-Message-State: AOAM533R4bstf35+0y6bKhymiARhMNq3mChH5KklQpxw5piEySFzXcdt Sm2sB403e+VZoacLi6xNWJSoLA== X-Google-Smtp-Source: ABdhPJwsKX0DV4kpdoFHr+1Rt0SRbjKnOiNtYc6LXPTb0BN3J77r+R9VhmAyqGrQhmlCaGL4aIc0uA== X-Received: by 2002:a17:90a:4504:: with SMTP id u4mr604587pjg.218.1611678614297; Tue, 26 Jan 2021 08:30:14 -0800 (PST) Received: from google.com ([2620:15c:f:10:1ea0:b8ff:fe73:50f5]) by smtp.gmail.com with ESMTPSA id v9sm2656146pju.33.2021.01.26.08.30.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Jan 2021 08:30:13 -0800 (PST) Date: Tue, 26 Jan 2021 08:30:07 -0800 From: Sean Christopherson To: Dave Hansen Cc: Kai Huang , linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, jarkko@kernel.org, luto@kernel.org, haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com Subject: Re: [RFC PATCH v3 03/27] x86/sgx: Remove a warn from sgx_free_epc_page() Message-ID: References: <36e999dce8a1a4efb8ca69c9a6fbe3fa63305e08.1611634586.git.kai.huang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Tue, Jan 26, 2021, Dave Hansen wrote: > On 1/26/21 1:30 AM, Kai Huang wrote: > > Remove SGX_EPC_PAGE_RECLAIMER_TRACKED check and warning. This cannot > > happen, as enclave pages are freed only at the time when encl->refcount > > triggers, i.e. when both VFS and the page reclaimer have given up on > > their references. > > > > Signed-off-by: Jarkko Sakkinen > > Signed-off-by: Kai Huang > > --- > > arch/x86/kernel/cpu/sgx/main.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > > index 8df81a3ed945..f330abdb5bb1 100644 > > --- a/arch/x86/kernel/cpu/sgx/main.c > > +++ b/arch/x86/kernel/cpu/sgx/main.c > > @@ -605,8 +605,6 @@ void sgx_free_epc_page(struct sgx_epc_page *page) > > struct sgx_epc_section *section = &sgx_epc_sections[page->section]; > > int ret; > > > > - WARN_ON_ONCE(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED); > > I'm all for cleaning up silly, useless warnings. But, don't we usually > put warnings in for things that we don't expect to be able to happen? > > In other words, I'm fine with removing this if it hasn't been a valuable > warning and we don't expect it to become a valuable warning. Ya, I don't understand the motivation for removing this warning. I tripped it more than once in the past during one of the many rebases of the virtual EPC and EPC cgroup branches.