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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id 66-20020a251545000000b00bcc0f2e4f05sm2365847ybv.59.2023.06.28.22.08.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jun 2023 22:08:19 -0700 (PDT) Date: Wed, 28 Jun 2023 22:08:08 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Gerald Schaefer Subject: Re: [PATCH v2 07/12] s390: add pte_free_defer() for pgtables sharing page In-Reply-To: <20230628211624.531cdc58@thinkpad-T15> Message-ID: References: <54cb04f-3762-987f-8294-91dafd8ebfb0@google.com> <20230628211624.531cdc58@thinkpad-T15> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Miaohe Lin , David Hildenbrand , Peter Zijlstra , Yang Shi , Peter Xu , linux-kernel@vger.kernel.org, Song Liu , sparclinux@vger.kernel.org, Alexander Gordeev , Claudio Imbrenda , Will Deacon , linux-s390@vger.kernel.org, Yu Zhao , Ira Weiny , Alistair Popple , Hugh Dickins , Russell King , Matthew Wilcox , Steven Price , Christoph Hellwig , Jason Gunthorpe , "Aneesh Kumar K.V" , Huang Ying , Axel Rasmussen , Christian Borntraeger , Thomas Hellstrom , Ralph Campbell , P asha Tatashin , Vasily Gorbik , Anshuman Khandual , Heiko Carstens , Qi Zheng , Suren Baghdasaryan , Vlastimil Babka , linux-arm-kernel@lists.infradead.org, SeongJae Park , Lorenzo Stoakes , Jann Horn , linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Naoya Horiguchi , Zack Rusin , Vishal Moola , Minchan Kim , "Kirill A. Shutemov" , Andrew Morton , Mel Gorman , "David S. Miller" , Mike Rapoport , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, 28 Jun 2023, Gerald Schaefer wrote: > > As discussed in the other thread, we would rather go with less complexity, > possibly switching to an approach w/o the list and fragment re-use in the > future. For now, as a first step in that direction, we can try with not > adding fragments back only for pte_free_defer(). Here is an adjusted > version of your patch, copying most of your pte_free_defer() logic and > also description, tested with LTP and all three of your patch series applied: Thanks, Gerald: I don't mind abandoning my 13/12 SLAB_TYPESAFE_BY_RCU patch (posted with fewer Cc's to the s390 list last week), and switching to your simpler who-cares-if-we-sometimes-don't-make-maximal-use-of-page patch. But I didn't get deep enough into it today to confirm it - and disappointed that you've found it necessary to play with pt_frag_refcount in addition to _refcount and HH bits. No real problem with that, but my instinct says it should be simpler. Tomorrow... Hugh