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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id v11-20020a25848b000000b00bf3438d6301sm4519026ybk.0.2023.07.04.09.03.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Jul 2023 09:03:41 -0700 (PDT) Date: Tue, 4 Jul 2023 09:03:29 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Alexander Gordeev cc: Hugh Dickins , Gerald Schaefer , Jason Gunthorpe , Andrew Morton , Vasily Gorbik , Mike Kravetz , Mike Rapoport , "Kirill A. Shutemov" , Matthew Wilcox , David Hildenbrand , Suren Baghdasaryan , Qi Zheng , Yang Shi , Mel Gorman , Peter Xu , Peter Zijlstra , Will Deacon , Yu Zhao , Alistair Popple , Ralph Campbell , Ira Weiny , Steven Price , SeongJae Park , Lorenzo Stoakes , Huang Ying , Naoya Horiguchi , Christophe Leroy , Zack Rusin , Axel Rasmussen , Anshuman Khandual , Pasha Tatashin , Miaohe Lin , Minchan Kim , Christoph Hellwig , Song Liu , Thomas Hellstrom , Russell King , "David S. Miller" , Michael Ellerman , "Aneesh Kumar K.V" , Heiko Carstens , Christian Borntraeger , Claudio Imbrenda , Jann Horn , Vishal Moola , Vlastimil Babka , linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 07/12] s390: add pte_free_defer() for pgtables sharing page In-Reply-To: Message-ID: References: <54cb04f-3762-987f-8294-91dafd8ebfb0@google.com> <20230628211624.531cdc58@thinkpad-T15> <20230629175645.7654d0a8@thinkpad-T15> <7bef5695-fa4a-7215-7e9d-d4a83161c7ab@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 96DAE1000AC X-Stat-Signature: cwshqkcsz9jny584ki11ctgs88ws5ugn X-HE-Tag: 1688486623-584170 X-HE-Meta: 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 UtY7RKsd T2Ik5SUyHIBkOgcRe8645cIjPOKEWkp3NLmquPG4yDOHmhhliMvT1MAwU9irev5uWdlS2p1GjQfkU05DVcHicMfiOU1ccVobJTIO0aT7DJ/uFQeBHH0QFhabi2QqcCL6SNoVsT6D5269Hmv6U1N+1MwuJ/2WwKJ6seLnwlNEAzstFPJAr0lB6LZn2cLWeUx04UIKyg9gKo17NVcRUSVL1IhbwcJlWGZC3/rUIDuc5DUr12/R8OgU84ZJA/ladzJLJ1MmkltOjSbMr/BDJ5gMlmblFMP97edklVO86iAQ27gYnEDovQ6FUo3sUXBNsYF89kSLonkA+9UwVAN/LeKhxTjFGv22rkozPBu7VaYBYgqmOf9SEk4VETd19sqWetLr8Kd+sY3xVNVv3k23uJTqAjUo8ynT8mifSMA2F4wQFzUE/bc25/vVTPHYnmONYDwvTGNUOr+CnqK57oINwii5daqKJinPhU2xZOdKR 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: On Tue, 4 Jul 2023, Alexander Gordeev wrote: > On Sat, Jul 01, 2023 at 09:32:38PM -0700, Hugh Dickins wrote: > > On Thu, 29 Jun 2023, Hugh Dickins wrote: > > Hi Hugh, > > ... > > No, not quite the same rules as before: I came to realize that using > > list_add_tail() for the HH pages would be liable to put a page on the > > list which forever blocked reuse of PP list_add_tail() pages after it > > (could be solved by a list_move() somewhere, but we have agreed to > > prefer simplicity). > > Just to make things more clear for me: do I understand correctly that this > was an attempt to add HH fragments to pgtable_list from pte_free_defer()? Yes, from page_table_free() called from pte_free_defer(): I had claimed they could be put on the list (or not) without needing to consider their HH-ness, apart from wanting to list_add_tail() rather than list_add() them. But then realized that this category of list_add_tail() pages would block access to the others. But I think I was mistaken then to say "could be solved by a list_move() somewhere"; because "somewhere" would have had to be __tlb_remove_table() when it removes PP-bits, which would bring us back to the issues of getting a spinlock from an mm which might already be freed. Hugh