From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4015C28CC5 for ; Wed, 5 Jun 2019 12:08:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9872C2067C for ; Wed, 5 Jun 2019 12:08:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727573AbfFEMIx (ORCPT ); Wed, 5 Jun 2019 08:08:53 -0400 Received: from imap1.codethink.co.uk ([176.9.8.82]:58082 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726305AbfFEMIx (ORCPT ); Wed, 5 Jun 2019 08:08:53 -0400 Received: from [167.98.27.226] (helo=xylophone) by imap1.codethink.co.uk with esmtpsa (Exim 4.84_2 #1 (Debian)) id 1hYUim-0006zs-UP; Wed, 05 Jun 2019 13:08:49 +0100 Message-ID: <1559736528.24330.87.camel@codethink.co.uk> Subject: Re: Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree From: Ben Hutchings To: Michal Hocko , Greg KH Cc: stable@vger.kernel.org, aarcange@redhat.com, akpm@linux-foundation.org, jannh@google.com, jgg@mellanox.com, oleg@redhat.com, peterx@redhat.com, rppt@linux.ibm.com, torvalds@linux-foundation.org, stable-commits@vger.kernel.org Date: Wed, 05 Jun 2019 13:08:48 +0100 In-Reply-To: <20190605065024.GA15685@dhcp22.suse.cz> References: <155965961313615@kroah.com> <20190604145216.GJ4669@dhcp22.suse.cz> <20190604150756.GA24221@kroah.com> <1559663498.24330.85.camel@codethink.co.uk> <20190605065024.GA15685@dhcp22.suse.cz> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Wed, 2019-06-05 at 08:50 +0200, Michal Hocko wrote: > On Tue 04-06-19 16:51:38, Ben Hutchings wrote: > [...] > > - I don't understand why collapse_huge_range() needs to be fixed, but > > then I really don't understand the khugepaged code at all!  So I would > > trust Michal on this. > > To be honest, I am not really sure myself here. But we are using a > remote mm there and I do not see anything that would prevent from racing > with exit/coredump. Maybe I am wrong. Let's wait for Andrea for his > review feedback. This patch is quite tricky for the stable backport. So, Greg, it seems like you should drop this from the current stable round. Ben. -- Ben Hutchings, Software Developer   Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom