From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752003AbbJSXSm (ORCPT ); Mon, 19 Oct 2015 19:18:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48282 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751140AbbJSXSl (ORCPT ); Mon, 19 Oct 2015 19:18:41 -0400 Date: Mon, 19 Oct 2015 16:18:40 -0700 From: Andrew Morton To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dave Hansen , Naoya Horiguchi , Hugh Dickins , Davidlohr Bueso Subject: Re: [PATCH 0/3] hugetlbfs fallocate hole punch race with page faults Message-Id: <20151019161840.63e6afaa73aceec23e351905@linux-foundation.org> In-Reply-To: <1445033310-13155-1-git-send-email-mike.kravetz@oracle.com> References: <1445033310-13155-1-git-send-email-mike.kravetz@oracle.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 16 Oct 2015 15:08:27 -0700 Mike Kravetz wrote: > The hugetlbfs fallocate hole punch code can race with page faults. The > result is that after a hole punch operation, pages may remain within the > hole. No other side effects of this race were observed. > > In preparation for adding userfaultfd support to hugetlbfs, it is desirable > to plug or significantly shrink this hole. This patch set uses the same > mechanism employed in shmem (see commit f00cdc6df7). > "still buggy but not as bad as before" isn't what we strive for ;) What would it take to fix this for real? An exhaustive description of the bug would be a good starting point, thanks.