From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3921380-1521235597-2-656216085260489229 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no ("Email failed DMARC policy for domain") X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='com', MailFrom='org' X-Spam-charsets: plain='iso-8859-1' X-IgnoreVacation: yes ("Email failed DMARC policy for domain") X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1521235596; b=S9YqTuuj8SXsTDKCSpwOTM8e2jEmKGLoSF2BUTmGWLyf/Ua k8ZyHYsnowIaYAQcn2zeXVvTZXVNITfWhDvno9wGD4hVfrnJ/kAF5CkqltEznoqC 0jW37Tfr6jEabLutYZACzzpPt1L1p/hoAt7pbPt+mNF63YW0tpGdGRGxepyoElGT CB+hYR0Csp6ERI31EmtdTFcZ4E8NtHRwUQITAIEOZI4nRrLSp5KSTudy4rHXRIdp iB3GmaEO3A8NIXgLwsOUAgl4Hiwvj6iAdUH1wzJ/dyCvj5Hg6L+dE0hGSisKxml5 WXhBnsVtrrYg+rNZnuS6vrA4dVBiP4qeNgN6lcw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:content-transfer-encoding :in-reply-to:sender:list-id; s=arctest; t=1521235596; bh=Zi4rvwE +YaqJFj3coV7UmuXeXwffjq1Z7lr1YvVqWHs=; b=YOah6xACMGPJSTBswi5YVVv a5NIR3wQHVByLcAW1cu+q62OLPxWiN5QLvKNm9yaF3yfSFJBibCJU7NKqLP2vSfg eryiTgqlw3ID7EHxyIqdoJBOoxJR2c4fOgd3zIv/RzEz+UxcImqthFv8e2Pv3mDs NzBOXGxtB2bbmdU7GnfpVzWDtvIqiu/pHaW7k3UtVS28MvotaBRsqnNPWDuaDedk V2uN+m54KquElC5n55R5I4m04AfUaoGf/8SCwBm69hYj51qLihcIvzAL0uiFKH4S z8kjefAYBf5OS3bkaRiKL5INMWbDh/QjnL+J+NFhVh6FitDPILU84PQm3YrXrpw= = ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751236AbeCPV0e (ORCPT ); Fri, 16 Mar 2018 17:26:34 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:46108 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750806AbeCPV0d (ORCPT ); Fri, 16 Mar 2018 17:26:33 -0400 Date: Fri, 16 Mar 2018 17:26:30 -0400 From: Jerome Glisse To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ralph Campbell , stable@vger.kernel.org, Evgeny Baskakov , Mark Hairgrove , John Hubbard Subject: Re: [PATCH 03/14] mm/hmm: HMM should have a callback before MM is destroyed v2 Message-ID: <20180316212630.GC4861@redhat.com> References: <20180316191414.3223-1-jglisse@redhat.com> <20180316191414.3223-4-jglisse@redhat.com> <20180316141221.f2b622630de3f1da51a5c105@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180316141221.f2b622630de3f1da51a5c105@linux-foundation.org> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Fri, Mar 16, 2018 at 02:12:21PM -0700, Andrew Morton wrote: > On Fri, 16 Mar 2018 15:14:08 -0400 jglisse@redhat.com wrote: > > > The hmm_mirror_register() function registers a callback for when > > the CPU pagetable is modified. Normally, the device driver will > > call hmm_mirror_unregister() when the process using the device is > > finished. However, if the process exits uncleanly, the struct_mm > > can be destroyed with no warning to the device driver. > > Again, what are the user-visible effects of the bug? Such info is > needed when others review our request for a -stable backport. And the > many people who review -stable patches for integration into their own > kernel trees will want to understand the benefit of the patch to their > users. I have not had any issues in any of my own testing but nouveau driver is not as advance as the NVidia closed driver in respect to HMM inte- gration yet. If any issues they will happen between exit_mm() and exit_files() in do_exit() (kernel/exit.c) exit_mm() tear down the mm struct but without this callback the device driver might still be handling page fault and thus might potentialy tries to handle them against a dead mm_struct. So i am not sure what are the symptoms. To be fair there is no public driver using that part of HMM beside nouveau rfc patches. So at this point the impact on anybody is non existent. If anyone want to back- port nouveau HMM support once it make it upstream it will probably have to backport more things along the way. This is why i am not that aggressive on ccing stable so far. Cheers, Jérôme