From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f72.google.com (mail-pa0-f72.google.com [209.85.220.72]) by kanga.kvack.org (Postfix) with ESMTP id 968CF6B0005 for ; Tue, 9 Aug 2016 05:58:37 -0400 (EDT) Received: by mail-pa0-f72.google.com with SMTP id ez1so16003938pab.1 for ; Tue, 09 Aug 2016 02:58:37 -0700 (PDT) Received: from mx0b-0016f401.pphosted.com (mx0a-0016f401.pphosted.com. [67.231.148.174]) by mx.google.com with ESMTPS id b132si41988840pfb.196.2016.08.09.02.58.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Aug 2016 02:58:36 -0700 (PDT) Received: from pps.filterd (m0045849.ppops.net [127.0.0.1]) by mx0a-0016f401.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u799nQ1S011289 for ; Tue, 9 Aug 2016 02:58:36 -0700 Received: from il-exch02.marvell.com ([199.203.130.102]) by mx0a-0016f401.pphosted.com with ESMTP id 24nd8q3q59-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Tue, 09 Aug 2016 02:58:36 -0700 From: Yehuda Yitschak Subject: [QUESTION] mmap of device file with huge pages Date: Tue, 9 Aug 2016 09:58:32 +0000 Message-ID: <85d8c7bb8bcc4a30865a4512dd174cf8@IL-EXCH02.marvell.com> Content-Language: en-US Content-Type: multipart/alternative; boundary="_000_85d8c7bb8bcc4a30865a4512dd174cf8ILEXCH02marvellcom_" MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: "linux-mm@kvack.org" Cc: Shadi Ammouri --_000_85d8c7bb8bcc4a30865a4512dd174cf8ILEXCH02marvellcom_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Hello everyone I am trying mmap kernel buffers associated with a device file (like /dev/m= em) using huge pages. I couldn't find any mechanism to do this. On the kernel side I allocate a contiguous 2M buffer using alloc_pages. A regular mmap with MAP_HUGETLB flag will only accept anonymous mappings or= hugetlbfs files but not device files. So, I think I need to make sure the mapping uses huge pages in my device fi= le's mmap hook. Usually these kind of mmap fops use remap_pfn_range but I couldn't find a w= ay to make remap_pfn_range use huge pages. I also tried to make Transparent huge pages recognize the mapping done with= remap_pfn_range and collapse them to a huge page but that didn't work. Not= sure why I would appreciate any advice on this issue Thanks ! ------------------- Yehuda Yitschak Marvell Semiconductor Ltd. --_000_85d8c7bb8bcc4a30865a4512dd174cf8ILEXCH02marvellcom_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hello everyone

I am trying mmap kernel buffers associated wit= h a device file (like /dev/mem) using huge pages.

I couldn’t find any mechanism to do this.=

On the kernel side I allocate a contiguous 2M buffer= using alloc_pages.

A regular mmap with MAP_HUGETLB flag will only accep= t anonymous mappings or hugetlbfs files but not device files.

So, I think I need to make sure the mapping uses hug= e pages in my device file’s mmap hook.

Usually these kind of mmap fops use remap_pfn_range = but I couldn’t find a way to make remap_pfn_range use huge pages.

I also tried to make Transparent huge pages recogniz= e the mapping done with remap_pfn_range and collapse them to a huge page bu= t that didn’t work. Not sure why

I would appreciate any advice on this issue

Thanks !

-------------------

Yehuda Yitschak

Marvell Semiconductor Ltd.

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