From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jerome Glisse Subject: Re: [PATCH hmm 03/15] mm/hmm: allow hmm_range to be used with a mmu_range_notifier or hmm_mirror Date: Mon, 21 Oct 2019 14:33:51 -0400 Message-ID: <20191021183351.GD3177@redhat.com> References: <20191015181242.8343-1-jgg@ziepe.ca> <20191015181242.8343-4-jgg@ziepe.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20191015181242.8343-4-jgg@ziepe.ca> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Jason Gunthorpe Cc: Andrea Arcangeli , Ralph Campbell , linux-rdma@vger.kernel.org, John Hubbard , Felix.Kuehling@amd.com, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Jason Gunthorpe , amd-gfx@lists.freedesktop.org, Ben Skeggs List-Id: amd-gfx.lists.freedesktop.org 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No, score=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 3F2F5CA9EAF for ; Mon, 21 Oct 2019 18:33:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 050AC2084C for ; Mon, 21 Oct 2019 18:33:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NMIrdim2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727017AbfJUSd6 (ORCPT ); Mon, 21 Oct 2019 14:33:58 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:51313 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726672AbfJUSd6 (ORCPT ); Mon, 21 Oct 2019 14:33:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571682836; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=heW2STh0qsJgZQvznrhVwfeqG1lZ93qzWcMlIpNclqY=; b=NMIrdim2wSElkPN7ugALfUU3qGT4OlL3msnNxLZmTtZD2JB0W+NvdMF3i8x5SoRLvvOntL ef0lbRAdIA3/IfM16JxhfKWivUGM6ANomxZ502QWBxC/+ePwb3noQvcyzx4gGTeiDohRt0 k6Ol3nj7Li+vwOMJ8VBGsq8LYHNOgiY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-184-_AN48j-3OTqbMRy9HXQccA-1; Mon, 21 Oct 2019 14:33:55 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 261C280183E; Mon, 21 Oct 2019 18:33:54 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.178]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1AECD60161; Mon, 21 Oct 2019 18:33:53 +0000 (UTC) Date: Mon, 21 Oct 2019 14:33:51 -0400 From: Jerome Glisse To: Jason Gunthorpe Cc: Ralph Campbell , John Hubbard , Felix.Kuehling@amd.com, linux-rdma@vger.kernel.org, linux-mm@kvack.org, Andrea Arcangeli , dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Ben Skeggs , Jason Gunthorpe Subject: Re: [PATCH hmm 03/15] mm/hmm: allow hmm_range to be used with a mmu_range_notifier or hmm_mirror Message-ID: <20191021183351.GD3177@redhat.com> References: <20191015181242.8343-1-jgg@ziepe.ca> <20191015181242.8343-4-jgg@ziepe.ca> MIME-Version: 1.0 In-Reply-To: <20191015181242.8343-4-jgg@ziepe.ca> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: _AN48j-3OTqbMRy9HXQccA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Oct 15, 2019 at 03:12:30PM -0300, Jason Gunthorpe wrote: > From: Jason Gunthorpe >=20 > hmm_mirror's handling of ranges does not use a sequence count which > results in this bug: >=20 > CPU0 CPU1 > hmm_range_wait_until_valid(range) > valid =3D=3D true > hmm_range_fault(range) > hmm_invalidate_range_start() > range->valid =3D false > hmm_invalidate_range_end() > range->valid =3D true > hmm_range_valid(range) > valid =3D=3D true >=20 > Where the hmm_range_valid should not have succeeded. >=20 > Adding the required sequence count would make it nearly identical to the > new mmu_range_notifier. Instead replace the hmm_mirror stuff with > mmu_range_notifier. >=20 > Co-existence of the two APIs is the first step. >=20 > Signed-off-by: Jason Gunthorpe Reviewed-by: J=E9r=F4me Glisse > --- > include/linux/hmm.h | 5 +++++ > mm/hmm.c | 25 +++++++++++++++++++------ > 2 files changed, 24 insertions(+), 6 deletions(-) >=20 > diff --git a/include/linux/hmm.h b/include/linux/hmm.h > index 3fec513b9c00f1..8ac1fd6a81af8f 100644 > --- a/include/linux/hmm.h > +++ b/include/linux/hmm.h > @@ -145,6 +145,9 @@ enum hmm_pfn_value_e { > /* > * struct hmm_range - track invalidation lock on virtual address range > * > + * @notifier: an optional mmu_range_notifier > + * @notifier_seq: when notifier is used this is the result of > + * mmu_range_read_begin() > * @hmm: the core HMM structure this range is active against > * @vma: the vm area struct for the range > * @list: all range lock are on a list > @@ -159,6 +162,8 @@ enum hmm_pfn_value_e { > * @valid: pfns array did not change since it has been fill by an HMM fu= nction > */ > struct hmm_range { > +=09struct mmu_range_notifier *notifier; > +=09unsigned long=09=09notifier_seq; > =09struct hmm=09=09*hmm; > =09struct list_head=09list; > =09unsigned long=09=09start; > diff --git a/mm/hmm.c b/mm/hmm.c > index 902f5fa6bf93ad..22ac3595771feb 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -852,6 +852,14 @@ void hmm_range_unregister(struct hmm_range *range) > } > EXPORT_SYMBOL(hmm_range_unregister); > =20 > +static bool needs_retry(struct hmm_range *range) > +{ > +=09if (range->notifier) > +=09=09return mmu_range_check_retry(range->notifier, > +=09=09=09=09=09 range->notifier_seq); > +=09return !range->valid; > +} > + > static const struct mm_walk_ops hmm_walk_ops =3D { > =09.pud_entry=09=3D hmm_vma_walk_pud, > =09.pmd_entry=09=3D hmm_vma_walk_pmd, > @@ -892,18 +900,23 @@ long hmm_range_fault(struct hmm_range *range, unsig= ned int flags) > =09const unsigned long device_vma =3D VM_IO | VM_PFNMAP | VM_MIXEDMAP; > =09unsigned long start =3D range->start, end; > =09struct hmm_vma_walk hmm_vma_walk; > -=09struct hmm *hmm =3D range->hmm; > +=09struct mm_struct *mm; > =09struct vm_area_struct *vma; > =09int ret; > =20 > -=09lockdep_assert_held(&hmm->mmu_notifier.mm->mmap_sem); > +=09if (range->notifier) > +=09=09mm =3D range->notifier->mm; > +=09else > +=09=09mm =3D range->hmm->mmu_notifier.mm; > + > +=09lockdep_assert_held(&mm->mmap_sem); > =20 > =09do { > =09=09/* If range is no longer valid force retry. */ > -=09=09if (!range->valid) > +=09=09if (needs_retry(range)) > =09=09=09return -EBUSY; > =20 > -=09=09vma =3D find_vma(hmm->mmu_notifier.mm, start); > +=09=09vma =3D find_vma(mm, start); > =09=09if (vma =3D=3D NULL || (vma->vm_flags & device_vma)) > =09=09=09return -EFAULT; > =20 > @@ -933,7 +946,7 @@ long hmm_range_fault(struct hmm_range *range, unsigne= d int flags) > =09=09=09start =3D hmm_vma_walk.last; > =20 > =09=09=09/* Keep trying while the range is valid. */ > -=09=09} while (ret =3D=3D -EBUSY && range->valid); > +=09=09} while (ret =3D=3D -EBUSY && !needs_retry(range)); > =20 > =09=09if (ret) { > =09=09=09unsigned long i; > @@ -991,7 +1004,7 @@ long hmm_range_dma_map(struct hmm_range *range, stru= ct device *device, > =09=09=09continue; > =20 > =09=09/* Check if range is being invalidated */ > -=09=09if (!range->valid) { > +=09=09if (needs_retry(range)) { > =09=09=09ret =3D -EBUSY; > =09=09=09goto unmap; > =09=09} > --=20 > 2.23.0 >=20