From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f197.google.com (mail-pf1-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id AAD8F8E0001 for ; Fri, 21 Dec 2018 05:28:31 -0500 (EST) Received: by mail-pf1-f197.google.com with SMTP id b17so4533016pfc.11 for ; Fri, 21 Dec 2018 02:28:31 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id h192sor38555847pgc.77.2018.12.21.02.28.30 for (Google Transport Security); Fri, 21 Dec 2018 02:28:30 -0800 (PST) Date: Fri, 21 Dec 2018 13:28:24 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH v2 2/2] hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race Message-ID: <20181221102824.5v36l6l5t2zthpgr@kshutemo-mobl1> References: <20181218223557.5202-1-mike.kravetz@oracle.com> <20181218223557.5202-3-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181218223557.5202-3-mike.kravetz@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Hugh Dickins , Naoya Horiguchi , "Aneesh Kumar K . V" , Andrea Arcangeli , "Kirill A . Shutemov" , Davidlohr Bueso , Prakash Sangappa , Andrew Morton , stable@vger.kernel.org On Tue, Dec 18, 2018 at 02:35:57PM -0800, Mike Kravetz wrote: > Instead of writing the required complicated code for this rare > occurrence, just eliminate the race. i_mmap_rwsem is now held in read > mode for the duration of page fault processing. Hold i_mmap_rwsem > longer in truncation and hold punch code to cover the call to > remove_inode_hugepages. One of remove_inode_hugepages() callers is noticeably missing -- hugetlbfs_evict_inode(). Why? It at least deserves a comment on why the lock rule doesn't apply to it. -- Kirill A. Shutemov