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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id j7-20020a816e07000000b00568e7e21db7sm103768ywc.96.2023.06.07.19.46.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jun 2023 19:46:36 -0700 (PDT) Date: Wed, 7 Jun 2023 19:46:26 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Jason Gunthorpe Subject: Re: [PATCH 07/12] s390: add pte_free_defer(), with use of mmdrop_async() In-Reply-To: Message-ID: References: <35e983f5-7ed3-b310-d949-9ae8b130cdab@google.com> <6dd63b39-e71f-2e8b-7e0-83e02f3bcb39@google.com> <175ebec8-761-c3f-2d98-6c3bd87161c8@google.com> 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 , "Aneesh Kumar K.V" , Axel Rasmussen , Gerald Schaefer , Christian Borntraeger , Thomas Hellstrom , Ralph Campbell , Pasha Tatashin , Vasily Gorbik , Anshuman Khandual , Heiko Carstens , Qi Zheng , Suren Baghdasaryan , linux-arm-kernel@lists.infradead.org, SeongJae Park , Jann Horn , linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Naoya Horiguchi , Zack Rusin , Minchan Kim , Mike Rapoport , Andrew Morton , Mel Gorman , "David S. Miller" , "Kirill A. Shutemov" , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, 6 Jun 2023, Jason Gunthorpe wrote: > On Mon, Jun 05, 2023 at 10:11:52PM -0700, Hugh Dickins wrote: > > > "deposited" pagetable fragments, over in arch/s390/mm/pgtable.c: use > > the first two longs of the page table itself for threading the list. > > It is not RCU anymore if it writes to the page table itself before the > grace period, so this change seems to break the RCU behavior of > page_table_free_rcu().. The rcu sync is inside tlb_remove_table() > called after the stores. Yes indeed, thanks for pointing that out. > > Maybe something like an xarray on the mm to hold the frags? I think we can manage without that: I'll say slightly more in reply to Gerald. Hugh