From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756505Ab3LVBbn (ORCPT ); Sat, 21 Dec 2013 20:31:43 -0500 Received: from ozlabs.org ([203.10.76.45]:55171 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756099Ab3LVBbY (ORCPT ); Sat, 21 Dec 2013 20:31:24 -0500 Date: Sun, 22 Dec 2013 00:58:19 +1100 From: David Gibson To: Joonsoo Kim Cc: Andrew Morton , Rik van Riel , Mel Gorman , Michal Hocko , "Aneesh Kumar K.V" , KAMEZAWA Hiroyuki , Hugh Dickins , Davidlohr Bueso , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Wanpeng Li , Naoya Horiguchi , Hillf Danton Subject: Re: [PATCH v3 03/14] mm, hugetlb: protect region tracking via newly introduced resv_map lock Message-ID: <20131221135819.GB12407@voom.fritz.box> References: <1387349640-8071-1-git-send-email-iamjoonsoo.kim@lge.com> <1387349640-8071-4-git-send-email-iamjoonsoo.kim@lge.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="5I6of5zJg18YgZEa" Content-Disposition: inline In-Reply-To: <1387349640-8071-4-git-send-email-iamjoonsoo.kim@lge.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --5I6of5zJg18YgZEa Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Dec 18, 2013 at 03:53:49PM +0900, Joonsoo Kim wrote: > There is a race condition if we map a same file on different processes. > Region tracking is protected by mmap_sem and hugetlb_instantiation_mutex. > When we do mmap, we don't grab a hugetlb_instantiation_mutex, but, > grab a mmap_sem. This doesn't prevent other process to modify region > structure, so it can be modified by two processes concurrently. >=20 > To solve this, I introduce a lock to resv_map and make region manipulation > function grab a lock before they do actual work. This makes region > tracking safe. It's not clear to me if you're saying there is a list corruption race bug in the existing code, or only that there will be if the instantiation mutex goes away. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --5I6of5zJg18YgZEa Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) iQIcBAEBAgAGBQJStZ57AAoJEGw4ysog2bOSBdEQAOaAOMmUK8EGKd1tAgG6wpF9 UydrFqPy5nTreKrDrL3PwTR/EXfoK6+nnH99sh1QR19iPSpkA4sgmzKvHqCfHk31 fBC8ry6Ghc8yyUEVCcSjwZ0UIE9sGFD+9PFB+/uLe+XzsO+bsTOk88AJQ5qyDBP6 7FP1ECjP0DZaBWrLfUpSjZbYy8VWzjwHvLfy78C+syrflfaQ9DQEEtEdTI6ZJpmV D7gT45jjuLvjuPIzSMk3d73GlkJxTlrNp2r3wF5nq+73i8OmG9MBL/NcvRWmvi59 ZxDTUPf8l34bqg8JdAIbzfRizeAPy1Wi5AXzqNs8eriJN8Esvq2mmtFm/1fTR8Hm VyKrLoEYN6/N6wcBAZLuwrZNe++OfowUn9+GkCkG7QEGxaMDZlDtzT4Lup8qmRvB tZlgujwR66m98keYa3a4CFlsnDiyfFiEvXg7Luwf419C4aH5sQlIRkHnxpv8v9Rz F3BKM/hnQ+VcdYKa0N5BEMCgi3yebtfbtZ0+c0ksMdPfdzUoP8EWc+MkzhbJpzRx mDOHOPm+nVWWgd3/hG88k/7a4/OEga+fYFaY/8UoJyL34Bi/iSRH/OnekiAi5DNi Esb5rRmAOCGXuWzK5b7Z2svlWqj56g/KM4fk2yGpuUf68wcGTezBqOuX7LbbX30d yxsXD8omoGoDjCzs99s/ =AvLd -----END PGP SIGNATURE----- --5I6of5zJg18YgZEa--