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spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726212AbeIDMVK (ORCPT ); Tue, 4 Sep 2018 08:21:10 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:45242 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725992AbeIDMVK (ORCPT ); Tue, 4 Sep 2018 08:21:10 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w847s4de136185; Tue, 4 Sep 2018 07:57:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2018-07-02; bh=+oMCoao0zulnlMU2aSZRrMMBwELOLGqK5pPOEryTBHQ=; b=LDqzS9Pm13gMp1Ao1VFNYxA79KCoRjeZsCU4PNJi46+NkYpk3nUZ0PjDROOEp1EL8YSi PailTk7+3Gam3bPG0nYWCooDO3DUMTLkcUMniZcGc688WoM7pbIHK7TcCQk0K7G4KUSV tCIs5GlY/1zcT+QpjsTBrsDqMxDeNlyUgKDstm+052WRo0Qe24WoC9vdvMeThstbI0ll jqqD1WiOwJt0hn/wfTBC2Y08/A7WnwllUmuX2v2GJ8eWyJU9KZyXdZhSALZZxROcBETh /PoyJZo6MuxmRmowhp+dPt46C/oWIRt+1gZkvkRFcIDc/x94YgjV1GLj6bVbeQX8P6em Mg== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp2120.oracle.com with ESMTP id 2m7jqpbahf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 04 Sep 2018 07:57:07 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w847v62H014847 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 4 Sep 2018 07:57:06 GMT Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w847v5bw029815; Tue, 4 Sep 2018 07:57:05 GMT Received: from ravellos-mbp.lan (/87.214.231.131) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 04 Sep 2018 00:57:05 -0700 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Re: [RFC][PATCH 3/5] [PATCH 3/5] kvm-ept-idle: HVA indexed EPT read From: Nikita Leshenko In-Reply-To: <20180901124811.591511876@intel.com> Date: Tue, 4 Sep 2018 09:57:01 +0200 Cc: Andrew Morton , Linux Memory Management List , Peng DongX , Liu Jingqi , Dong Eddie , Dave Hansen , Huang Ying , Brendan Gregg , kvm@vger.kernel.org, LKML Content-Transfer-Encoding: 7bit Message-Id: <37B30FD3-7955-4C0B-AAB5-544359F4D157@oracle.com> References: <20180901112818.126790961@intel.com> <20180901124811.591511876@intel.com> To: Fengguang Wu X-Mailer: Apple Mail (2.3445.9.1) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9005 signatures=668708 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=718 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809040084 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1 Sep 2018, at 13:28, Fengguang Wu wrote: > +static ssize_t ept_idle_read(struct file *file, char *buf, > + size_t count, loff_t *ppos) > +{ > + struct task_struct *task = file->private_data; > + struct ept_idle_ctrl *eic; > + unsigned long hva_start = *ppos << BITMAP_BYTE2PVA_SHIFT; > + unsigned long hva_end = hva_start + (count << BITMAP_BYTE2PVA_SHIFT); > + int ret; > + > + if (*ppos % IDLE_BITMAP_CHUNK_SIZE || > + count % IDLE_BITMAP_CHUNK_SIZE) > + return -EINVAL; > + > + eic = kzalloc(sizeof(*eic), GFP_KERNEL); > + if (!eic) > + return -EBUSY; > + > + eic->buf = buf; > + eic->buf_size = count; > + eic->kvm = task_kvm(task); > + if (!eic->kvm) { > + ret = -EINVAL; > + goto out_free; > + } I think you need to increment the refcount while using kvm, otherwise kvm can be destroyed from another thread while you're walking it. -Nikita > + > + ret = ept_idle_walk_hva_range(eic, hva_start, hva_end); > + if (ret) > + goto out_free; > + > + ret = eic->bytes_copied; > + *ppos += ret; > +out_free: > + kfree(eic); > + > + return ret; > +}