Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423007AbbD2NGH (ORCPT ); Wed, 29 Apr 2015 09:06:07 -0400 Received: from thoth.sbs.de ([192.35.17.2]:48318 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422850AbbD2NGE (ORCPT ); Wed, 29 Apr 2015 09:06:04 -0400 Message-ID: <5540D735.5030103@siemens.com> Date: Wed, 29 Apr 2015 15:05:57 +0200 From: Jan Kiszka User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 To: Bandan Das CC: kvm@vger.kernel.org, Paolo Bonzini , Wincy Van , linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: nVMX: Don't return error on nested bitmap memory allocation failure References: <554083D4.8090906@siemens.com> In-Reply-To: Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1515 Lines: 35 Am 2015-04-29 um 14:55 schrieb Bandan Das: > Jan Kiszka writes: > >> Am 2015-04-28 um 21:55 schrieb Bandan Das: >>> >>> If get_free_page() fails for nested bitmap area, it's evident that >>> we are gonna get screwed anyway but returning failure because we failed >>> allocating memory for a nested structure seems like an unnecessary big >>> hammer. Also, save the call for later; after we are done with other >>> non-nested allocations. >> >> Frankly, I prefer failures over automatic degradations. And, as you >> noted, the whole system will probably explode anyway if allocation of a >> single page already fails. So what does this buy us? > > Yeah... I hear you. Ok, let me put it this way - Assume that we can > defer this allocation up until the point that the nested subsystem is > actually used i.e L1 tries running a guest and we try to allocate this > area. If get_free_page() failed in that case, would we still want to > kill L1 too ? I guess no. We could block the hypervisor thread on the allocation, just like it would block on faults for swapped out pages or new ones that have to be reclaimed from the page cache first. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/