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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13AEDC433EF for ; Thu, 10 Mar 2022 18:01:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245321AbiCJSCp (ORCPT ); Thu, 10 Mar 2022 13:02:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234616AbiCJSCo (ORCPT ); Thu, 10 Mar 2022 13:02:44 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FD8B197B78; Thu, 10 Mar 2022 10:01:43 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D3EA7B8278D; Thu, 10 Mar 2022 18:01:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07274C340E8; Thu, 10 Mar 2022 18:01:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646935300; bh=Ehed+d1AEXVa5J2E1toVI+Dn/MDgVrfaiJcmSqyAOuU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=brMd6jeMiCgX3+4y+Xa9b0xDYmgzBPhI+UCeko4yYEy6Qt5M7usGrhriLweB1NWbz buMDiSB/dO9anfLDyTS+b7ycQfNqBFzjLdMBys3+VyYlSFWDeG4a8a2RJXU3MYqsc2 8O131NBYY8lcHgDuYH8rGR5okCSXsBdEqOc4VhD63N1KRo9yLhymm+vk7uLcNlLorM ZxSvANeo+8484M3uw5dBboFcCiand2dpj0e8YiPLzT+EDlarP7+d+zX+k2awVLpHuT oRQyKqtEmFLbr8eq6wRS/tTOHE5IRFCq3Ni/r4p51ExFx8jJfACMsT+0RvcAq2PyxT z8WeTllWfGrxA== Date: Thu, 10 Mar 2022 20:00:55 +0200 From: Jarkko Sakkinen To: Reinette Chatre , Dave Hansen Cc: linux-sgx@vger.kernel.org, stable@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , "H. Peter Anvin" , Jethro Beekman , Sean Christopherson , "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" Subject: Re: [PATCH v6] x86/sgx: Free backing memory after faulting the enclave page Message-ID: References: <20220303223859.273187-1-jarkko@kernel.org> 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-kernel@vger.kernel.org On Wed, Mar 09, 2022 at 10:01:17AM +0200, Jarkko Sakkinen wrote: > On Tue, Mar 08, 2022 at 11:16:19AM -0800, Reinette Chatre wrote: > > Hi, > > > > On 3/3/2022 2:38 PM, Jarkko Sakkinen wrote: > > > There is a limited amount of SGX memory (EPC) on each system. When that > > > memory is used up, SGX has its own swapping mechanism which is similar > > > in concept but totally separate from the core mm/* code. Instead of > > > swapping to disk, SGX swaps from EPC to normal RAM. That normal RAM > > > comes from a shared memory pseudo-file and can itself be swapped by the > > > core mm code. There is a hierarchy like this: > > > > > > EPC <-> shmem <-> disk > > > > > > After data is swapped back in from shmem to EPC, the shmem backing > > > storage needs to be freed. Currently, the backing shmem is not freed. > > > This effectively wastes the shmem while the enclave is running. The > > > memory is recovered when the enclave is destroyed and the backing > > > storage freed. > > > > > > Sort this out by freeing memory with shmem_truncate_range(), as soon as > > > a page is faulted back to the EPC. In addition, free the memory for > > > PCMD pages as soon as all PCMD's in a page have been marked as unused > > > by zeroing its contents. > > > > > > Reported-by: Dave Hansen > > > Cc: stable@vger.kernel.org > > > Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer") > > > Signed-off-by: Jarkko Sakkinen > > > > I can reliably reproduce the issue this patch aims to solve by creating > > a virtual machine that has a significant portion of its memory consumed > > by EPC: > > > > qemu-system-x86_64 -smp 4 -m 4G\ > > -enable-kvm \ > > -cpu host,+sgx-provisionkey \ > > -object memory-backend-ram,size=2G,host-nodes=0,policy=bind,id=node0 \ > > -object memory-backend-epc,id=mem0,size=1536M,prealloc=on,host-nodes=0,policy=bind \ > > -numa node,nodeid=0,cpus=0-1,memdev=node0 \ > > -object memory-backend-ram,size=2G,host-nodes=1,policy=bind,id=node1 \ > > -object memory-backend-epc,id=mem1,size=1536M,prealloc=on,host-nodes=1,policy=bind \ > > -numa node,nodeid=1,cpus=2-3,memdev=node1 \ > > -M sgx-epc.0.memdev=mem0,sgx-epc.0.node=0,sgx-epc.1.memdev=mem1,sgx-epc.1.node=1 \ > > ... > > > > Before this patch, running the very stressful SGX2 over subscription test case > > (unclobbered_vdso_oversubscribed_remove) in this environment always triggers > > the oom-killer but no amount of tasks killed can save the system > > with it always ending deadlocked on memory: > > > > [ 58.642719] Tasks state (memory values in pages): > > [ 58.644324] [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name > > [ 58.647237] [ 195] 0 195 3153 197 45056 0 -1000 systemd-udevd > > [ 58.650238] [ 281] 0 281 1836367 0 10817536 0 0 test_sgx > > [ 58.653088] Out of memory and no killable processes... > > [ 58.654832] Kernel panic - not syncing: System is deadlocked on memory > > > > After applying this patch I was able to run SGX2 selftest > > unclobbered_vdso_oversubscribed_remove ten times successfully. > > > > Tested-by: Reinette Chatre > > Thank you. > > > Reinette Dave, can this be picked up? BR, Jarkko