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Tue, 21 Nov 2023 14:47:19 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D677E2004D; Tue, 21 Nov 2023 14:47:18 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B4D9A2004F; Tue, 21 Nov 2023 14:47:18 +0000 (GMT) Received: from osiris (unknown [9.152.212.60]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTPS; Tue, 21 Nov 2023 14:47:18 +0000 (GMT) Date: Tue, 21 Nov 2023 15:47:17 +0100 From: Heiko Carstens To: Alexander Gordeev Cc: Vishal Moola , linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Gerald Schaefer Subject: Re: [PATCH] pgtable: do not expose _refcount field via ptdesc Message-ID: <20231121144717.6318-A-hca@linux.ibm.com> References: <20231121120310.696335-1-agordeev@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231121120310.696335-1-agordeev@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: RTfch-c1H22NI79LYQCs1Wnt6Z8SobN_ X-Proofpoint-GUID: fiBSlMlH0We5yBP55yGtCmvKv_vNJ-za X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.987,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-11-21_07,2023-11-21_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 lowpriorityscore=0 suspectscore=0 impostorscore=0 mlxscore=0 priorityscore=1501 mlxlogscore=811 adultscore=0 malwarescore=0 spamscore=0 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311060000 definitions=main-2311210115 X-Rspam-User: X-Stat-Signature: 9ksr17hgod9tq1tchzbketwzxka5gnyd X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 55BAA20011 X-HE-Tag: 1700578044-326402 X-HE-Meta: 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 BskFQu1D 25ufk4Lfp/JJXuwN/wRdHlqBrwu4Rr/Ja9OHcCdRBl+oQawYOIhIGsjCTaLv7xv+nxtL0TF79Nl6XczaA+0Or9JR2f3fqD9C1kNyOFLK89AmvG222e+IvhfHPiE5UGf0w1N14umq7BdoVh0lEgSnwfw39Ru2czxcJWfULQMn/FkEjUeAEm4D9hAn5cAIu2HFvJCte8qv+fUEaW2KIxL9JtRIYCoQiaQ0m7fW94EOpr/BYSBHKYNLOZD9bibtHFSpfGQYan5bbBPi2tKi1qtVo1EnL3x9YeCZTph/ONsZxcyU7wC9ERv5cV1zblF+FgUbDFxaYtf72vX8ux+zYMnCAoMmrwqpJFqc2Owi+ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Nov 21, 2023 at 01:03:10PM +0100, Alexander Gordeev wrote: > Since commit d08d4e7cd6bf ("s390/mm: use full 4KB page for 2KB PTE") > _refcount field is not used for fragmented page tracking on s390 and > there is no other code left that accesses this field explicitly. > > Suggested-by: Heiko Carstens > Signed-off-by: Alexander Gordeev > --- > include/linux/mm_types.h | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 957ce38768b2..0330e0ddca11 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -401,11 +401,10 @@ FOLIO_MATCH(compound_head, _head_2a); > * @pmd_huge_pte: Protected by ptdesc->ptl, used for THPs. > * @__page_mapping: Aliases with page->mapping. Unused for page tables. > * @pt_mm: Used for x86 pgds. > - * @pt_frag_refcount: For fragmented page table tracking. Powerpc and s390 only. > + * @pt_frag_refcount: For fragmented page table tracking. Powerpc only. > * @_pt_pad_2: Padding to ensure proper alignment. > * @ptl: Lock for the page table. > * @__page_type: Same as page->page_type. Unused for page tables. > - * @_refcount: Same as page refcount. Used for s390 page tables. I would guess that you need to describe _pt_pad_3 instead here, just like it is done for the other two pad members. And most likely you need to add Andrew to "To:" so he doesn't miss this :)