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Fri, 15 Sep 2023 17:54:51 +0000 (GMT) Date: Fri, 15 Sep 2023 19:54:50 +0200 From: Claudio Imbrenda To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , linux-mm@kvack.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , linux-s390@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH 0/3] Use arch_make_folio_accessible() everywhere Message-ID: <20230915195450.1fd35f48@p-imbrenda> In-Reply-To: <20230915172829.2632994-1-willy@infradead.org> References: <20230915172829.2632994-1-willy@infradead.org> Organization: IBM X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: -qdZCiIKDqTehVkEeLmO5vr7qd8z_a9Y X-Proofpoint-GUID: -qdZCiIKDqTehVkEeLmO5vr7qd8z_a9Y X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-09-15_14,2023-09-15_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 malwarescore=0 priorityscore=1501 mlxscore=0 bulkscore=0 phishscore=0 adultscore=0 suspectscore=0 spamscore=0 lowpriorityscore=0 impostorscore=0 mlxlogscore=936 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2308100000 definitions=main-2309150157 X-Rspamd-Queue-Id: 907C2180015 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: qk1ayaz9tzmf7rtocnhbefqqayjeozb1 X-HE-Tag: 1694800504-37600 X-HE-Meta: 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 jICfp3l1 e0OSmwzrX7+8WIeeRY52dfqM29/hhC1+rVvh7ovMypuxRCCxIh6trJimMVKGRKCD27/H/ZKSf17XpCQiPbb+lmP2lAEEwuWUSAZmmqjDsbpw/3t+Hp2KwIrKD2tuX7sHpDC9MC1gDrQUYpHo3Unr85UJThluLz3E2pslHmswNzLmd4JQbcqT1ylw6s5IhL/oCZ0bmeaUGlidtGRk+DWLB8ssB2zh94o6xkMN9d0tX3Xyf5kTAYlhZrd/Nfgp29hqjrkS64qxWWqSVsiHZkATN7zyvjiRDwtUMaMjnolWkHb0GGD7/8KOSBVgDJYyr/OWHrEicmAQpUsZEtYk+OuJqxB5kY+NIFhbf66bGh5t9jPLvkB4e0zMcqDDB6CT8FdVbHfspyKAYlcP2NRZBgPVqqXviqtlYObr0pLxNgMxurabSVxM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 15 Sep 2023 18:28:25 +0100 "Matthew Wilcox (Oracle)" wrote: > We introduced arch_make_folio_accessible() a couple of years > ago, and it's in use in the page writeback path. GUP still uses > arch_make_page_accessible(), which means that we can succeed in making > a single page of a folio accessible, then fail to make the rest of the > folio accessible when it comes time to do writeback and it's too late > to do anything about it. I'm not sure how much of a real problem this is. > > Switching everything around to arch_make_folio_accessible() also lets > us switch the page flag to be per-folio instead of per-page, which is > a good step towards dynamically allocated folios. > > Build-tested only. > > Matthew Wilcox (Oracle) (3): > mm: Use arch_make_folio_accessible() in gup_pte_range() > mm: Convert follow_page_pte() to use a folio > s390: Convert arch_make_page_accessible() to > arch_make_folio_accessible() > > arch/s390/include/asm/page.h | 5 ++-- > arch/s390/kernel/uv.c | 46 +++++++++++++++++++++++------------- > arch/s390/mm/fault.c | 15 ++++++------ > include/linux/mm.h | 20 ++-------------- > mm/gup.c | 22 +++++++++-------- > 5 files changed, 54 insertions(+), 54 deletions(-) > if I understand correctly, this will as a matter of fact move the security property from pages to folios. this means that trying to access a page will (try to) make the whole folio accessible, even though that might be counterproductive.... and there is no way to simply split a folio I don't like this there are also other reasons, but I don't have time to go into the details on a Friday evening (will elaborate more on Monday)