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[156.151.31.86]) by mx.google.com with ESMTPS id 129si4669428ybz.318.2019.05.20.08.30.57 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 May 2019 08:30:58 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.m.jordan@oracle.com designates 156.151.31.86 as permitted sender) client-ip=156.151.31.86; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=LDlo2Jtn; spf=pass (google.com: domain of daniel.m.jordan@oracle.com designates 156.151.31.86 as permitted sender) smtp.mailfrom=daniel.m.jordan@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x4KFIvpF144705; Mon, 20 May 2019 15:30:35 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=SXUGhLzqu7OWeZA9OhKeGyoXs0a41JQJFMDBXBRPnVs=; b=LDlo2JtnsgqOL7mMI0IvGprzfGCy4to4pDQltq8uHsDWRMZ5fLF/GBmkz/DPJG16d8+E AphQu0yTg9IX/1qILAVa03FMrn/a0QMIcIuzCfG1x9RXcoTeKLnRbqhxI/u2l3T5i+FO sRlFZbwrPkqowmNwuDTdSihMC/nz2onnFmvR1s6zTFTGeAGe8PUto+cDd13QJ16HajNT QbD1ITdOCo1utBuP6VExYHrORa14RnduNx9MSIKtrhSnSUFWInHvA7sGpIa4C3sHrOG/ WMBhF9YM8ifc8XjdVeMUyguDzXTtV5vjfUAJ6BjL40xkPh1CGr3Uvt8OkhE+dqxwuqE3 /g== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2130.oracle.com with ESMTP id 2sj9ft7sn9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 May 2019 15:30:35 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x4KFTuDs046722; Mon, 20 May 2019 15:30:34 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 2sks18nr8g-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 May 2019 15:30:34 +0000 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 x4KFUL5K012431; Mon, 20 May 2019 15:30:21 GMT Received: from ca-dmjordan1.us.oracle.com (/10.211.9.48) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 20 May 2019 15:30:21 +0000 Date: Mon, 20 May 2019 11:30:20 -0400 From: Daniel Jordan To: Alexey Kardashevskiy Cc: Daniel Jordan , akpm@linux-foundation.org, Alan Tull , Alex Williamson , Benjamin Herrenschmidt , Christoph Lameter , Christophe Leroy , Davidlohr Bueso , Jason Gunthorpe , Mark Rutland , Michael Ellerman , Moritz Fischer , Paul Mackerras , Steve Sistare , Wu Hao , linux-mm@kvack.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: add account_locked_vm utility function Message-ID: <20190520153020.mzvjsjwefwxz6cau@ca-dmjordan1.us.oracle.com> References: <20190503201629.20512-1-daniel.m.jordan@oracle.com> <4b42057f-b998-f87c-4e0f-a91abcb366f9@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4b42057f-b998-f87c-4e0f-a91abcb366f9@ozlabs.ru> User-Agent: NeoMutt/20180323-268-5a959c X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9262 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=18 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905200100 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9262 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=18 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905200100 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 20, 2019 at 04:19:34PM +1000, Alexey Kardashevskiy wrote: > On 04/05/2019 06:16, Daniel Jordan wrote: > > locked_vm accounting is done roughly the same way in five places, so > > unify them in a helper. Standardize the debug prints, which vary > > slightly. > > And I rather liked that prints were different and tell precisely which > one of three each printk is. I'm not following. One of three...callsites? But there were five callsites. Anyway, I added a _RET_IP_ to the debug print so you can differentiate. > I commented below but in general this seems working. > > Tested-by: Alexey Kardashevskiy Thanks! And for the review as well. > > diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c > > index 6b64e45a5269..d39a1b830d82 100644 > > --- a/drivers/vfio/vfio_iommu_spapr_tce.c > > +++ b/drivers/vfio/vfio_iommu_spapr_tce.c > > @@ -34,49 +35,13 @@ > > static void tce_iommu_detach_group(void *iommu_data, > > struct iommu_group *iommu_group); > > > > -static long try_increment_locked_vm(struct mm_struct *mm, long npages) > > +static int tce_account_locked_vm(struct mm_struct *mm, unsigned long npages, > > + bool inc) > > { > > - long ret = 0, locked, lock_limit; > > - > > if (WARN_ON_ONCE(!mm)) > > return -EPERM; > > > If this WARN_ON is the only reason for having tce_account_locked_vm() > instead of calling account_locked_vm() directly, you can then ditch the > check as I have never ever seen this triggered. Great, will do. > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > > index d0f731c9920a..15ac76171ccd 100644 > > --- a/drivers/vfio/vfio_iommu_type1.c > > +++ b/drivers/vfio/vfio_iommu_type1.c > > @@ -273,25 +273,14 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async) > > return -ESRCH; /* process exited */ > > > > ret = down_write_killable(&mm->mmap_sem); > > - if (!ret) { > > - if (npage > 0) { > > - if (!dma->lock_cap) { > > - unsigned long limit; > > - > > - limit = task_rlimit(dma->task, > > - RLIMIT_MEMLOCK) >> PAGE_SHIFT; > > - > > - if (mm->locked_vm + npage > limit) > > - ret = -ENOMEM; > > - } > > - } > > + if (ret) > > + goto out; > > > A single "goto" to jump just 3 lines below seems unnecessary. No strong preference here, I'll take out the goto. > > +int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc, > > + struct task_struct *task, bool bypass_rlim) > > +{ > > + unsigned long locked_vm, limit; > > + int ret = 0; > > + > > + locked_vm = mm->locked_vm; > > + if (inc) { > > + if (!bypass_rlim) { > > + limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT; > > + if (locked_vm + pages > limit) { > > + ret = -ENOMEM; > > + goto out; > > + } > > + } > > Nit: > > if (!ret) > > and then you don't need "goto out". Ok, sure. > > + mm->locked_vm = locked_vm + pages; > > + } else { > > + WARN_ON_ONCE(pages > locked_vm); > > + mm->locked_vm = locked_vm - pages; > > > Can go negative here. Not a huge deal but inaccurate imo. I hear you, but setting a negative value to zero, as we had done previously, doesn't make much sense to me.