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Tue, 1 Oct 2024 10:43:13 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6B84420049; Tue, 1 Oct 2024 10:43:13 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8521C20040; Tue, 1 Oct 2024 10:43:11 +0000 (GMT) Received: from thinkpad-T15 (unknown [9.171.59.94]) by smtpav06.fra02v.mail.ibm.com (Postfix) with SMTP; Tue, 1 Oct 2024 10:43:11 +0000 (GMT) Date: Tue, 1 Oct 2024 12:43:09 +0200 From: Gerald Schaefer To: Dan Williams Cc: Alistair Popple , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 05/12] mm/memory: Add dax_insert_pfn Message-ID: <20241001124309.782004b8@thinkpad-T15> In-Reply-To: <66ef75e59c7ea_109b5294d1@dwillia2-mobl3.amr.corp.intel.com.notmuch> References: <110d5b177d793ab17ea5d1210606cb7dd0f82493.1725941415.git-series.apopple@nvidia.com> <66ef75e59c7ea_109b5294d1@dwillia2-mobl3.amr.corp.intel.com.notmuch> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) Content-Type: text/plain; charset=US-ASCII X-TM-AS-GCONF: 00 X-Proofpoint-GUID: mLp8W3ZTWJaathMCFPKloMnlrxlln_bF X-Proofpoint-ORIG-GUID: 5FfpjjtfUKsGqxfrBWkGoY0YounV3Quc Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-01_07,2024-09-30_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 mlxlogscore=928 mlxscore=0 priorityscore=1501 clxscore=1011 spamscore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 phishscore=0 suspectscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2408220000 definitions=main-2410010066 On Sun, 22 Sep 2024 03:41:57 +0200 Dan Williams wrote: > [ add s390 folks to comment on CONFIG_FS_DAX_LIMITED ] [...] > > @@ -2516,6 +2545,44 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, > > return VM_FAULT_NOPAGE; > > } > > > > +vm_fault_t dax_insert_pfn(struct vm_fault *vmf, pfn_t pfn_t, bool write) > > +{ > > + struct vm_area_struct *vma = vmf->vma; > > + pgprot_t pgprot = vma->vm_page_prot; > > + unsigned long pfn = pfn_t_to_pfn(pfn_t); > > + struct page *page = pfn_to_page(pfn); > > The problem here is that we stubbornly have __dcssblk_direct_access() to > worry about. That is the only dax driver that does not return > pfn_valid() pfns. > > In fact, it looks like __dcssblk_direct_access() is the only thing > standing in the way of the removal of pfn_t. > > It turns out it has been 3 years since the last time the question of > bringing s390 fully into the ZONE_DEVICE regime was raised: > > https://lore.kernel.org/all/20210820210318.187742e8@thinkpad/ > > Given that this series removes PTE_DEVMAP which was a stumbling block, > would it be feasible to remove CONFIG_FS_DAX_LIMITED for a few kernel > cycles until someone from the s390 side can circle back to add full > ZONE_DEVICE support? Yes, see also my reply to your "dcssblk: Mark DAX broken" patch. Thanks Alistair for your effort, making ZONE_DEVICE usable w/o extra PTE bit!