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 CCE43C433EF for ; Mon, 11 Apr 2022 14:11:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346988AbiDKONd (ORCPT ); Mon, 11 Apr 2022 10:13:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346980AbiDKONa (ORCPT ); Mon, 11 Apr 2022 10:13:30 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4464431DFE for ; Mon, 11 Apr 2022 07:11:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649686276; x=1681222276; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=frC20TMIzMSN3lrgDTo+z6mOXOf30jMlelae8Bj8uAA=; b=AUZdiQbQ9VmmfdnUZ3RQ/bZl5+R7elk0NuzxznXNgmLAwl7v64BqFS4E +BYiWcFRKl8PcZZWy+5n9OplUV3It5Lfr6f/H51RHAitPyGEq5A/N+lJt fCVWdH78S55JgQQCsDfoZylq3swn9qllLwVI06DqP52fDEhgIiem82TUP VUFvCKX6cNR4CVZffSsWOt/nJGsqfyh4kHyF/UJ1IjDjhnmjeJkVddBIy 8lormWn5uxS29YA35rQko+ZSwUk7Md6qayCYCjrK+PWvgKSA9kKBgbquJ J/CqDHZ6pWQQ7aXezGuA4zGBv0HLgWRth8UqpVC1nqzt0CflxrT/q6syF Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10314"; a="242063272" X-IronPort-AV: E=Sophos;i="5.90,252,1643702400"; d="scan'208";a="242063272" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Apr 2022 07:10:40 -0700 X-IronPort-AV: E=Sophos;i="5.90,252,1643702400"; d="scan'208";a="525550119" Received: from srkondle-mobl.amr.corp.intel.com (HELO [10.212.113.6]) ([10.212.113.6]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Apr 2022 07:10:38 -0700 Message-ID: <56ed509d-a7cf-1fde-676c-a28eb204989b@intel.com> Date: Mon, 11 Apr 2022 07:10:43 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Content-Language: en-US To: Zhangfei Gao , Joerg Roedel , Fenghua Yu , jean-philippe Cc: Ravi V Shankar , Tony Luck , Ashok Raj , Peter Zijlstra , Dave Hansen , x86 , linux-kernel , iommu , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Josh Poimboeuf , Thomas Gleixner References: <20220207230254.3342514-1-fenghua.yu@intel.com> <20220207230254.3342514-6-fenghua.yu@intel.com> From: Dave Hansen Subject: Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/11/22 07:00, Zhangfei Gao wrote: > with this patchset, each time after sbin/nginx, ioasid is freed > immediately. lynx test will alloc the same ioasid=1. That doesn't seem right. Isn't 'sbin/nginx' still running when lynx runs? How can they get the same ioasid? This sounds like a refcounting problem, like that the ioasid wasn't properly refcounted as nginx forked into the background. > To verify, hack comment mm_pasid_drop in __mmput will make the issue > disappear. > > log: after sbin/nginx. > [   96.526730] Call trace: > [   96.526732]  dump_backtrace+0xe4/0xf0 > [   96.526741]  show_stack+0x20/0x70 > [   96.526744]  dump_stack_lvl+0x8c/0xb8 > [   96.526751]  dump_stack+0x18/0x34 > [   96.526754]  ioasid_free+0xdc/0xfc > [   96.526757]  mmput+0x138/0x160 > [   96.526760]  do_exit+0x284/0x9d0 > [   96.526765]  do_group_exit+0x3c/0xa8 > [   96.526767]  __wake_up_parent+0x0/0x38 > [   96.526770]  invoke_syscall+0x4c/0x110 > [   96.526775]  el0_svc_common.constprop.0+0x68/0x128 > [   96.526778]  do_el0_svc+0x2c/0x90 > [   96.526781]  el0_svc+0x30/0x98 > [   96.526783]  el0t_64_sync_handler+0xb0/0xb8 > [   96.526785]  el0t_64_sync+0x18c/0x190 Is there nothing before this call trace? Usually there will be at least some warning text.