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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id x126sm6934696qkb.101.2020.09.10.10.19.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2020 10:19:57 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kGQEm-004NzL-RL; Thu, 10 Sep 2020 14:19:56 -0300 Date: Thu, 10 Sep 2020 14:19:56 -0300 From: Jason Gunthorpe To: Gerald Schaefer Cc: Anshuman Khandual , Alexander Gordeev , Dave Hansen , John Hubbard , LKML , linux-mm , linux-arch , Andrew Morton , Linus Torvalds , Russell King , Mike Rapoport , Catalin Marinas , Will Deacon , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Jeff Dike , Richard Weinberger , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Arnd Bergmann , Andrey Ryabinin , linux-x86 , linux-arm , linux-power , linux-sparc , linux-um , linux-s390 , Vasily Gorbik , Heiko Carstens , Christian Borntraeger , Claudio Imbrenda Subject: Re: [RFC PATCH v2 1/3] mm/gup: fix gup_fast with dynamic page table folding Message-ID: <20200910171956.GM87483@ziepe.ca> References: <0dbc6ec8-45ea-0853-4856-2bc1e661a5a5@intel.com> <20200909142904.00b72921@thinkpad> <20200909192534.442f8984@thinkpad> <20200909180324.GI87483@ziepe.ca> <20200910093925.GB29166@oc3871087118.ibm.com> <20200910130233.GK87483@ziepe.ca> <20200910152803.1a930afc@thinkpad> <20200910151026.GL87483@ziepe.ca> <20200910190757.153319d4@thinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200910190757.153319d4@thinkpad> X-Rspamd-Queue-Id: 8103E1803008C X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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 Thu, Sep 10, 2020 at 07:07:57PM +0200, Gerald Schaefer wrote: > I might have lost track a bit. Are we still talking about possible > functional impacts of either our current pagetable walking with s390 > (apart from gup_fast), or the proposed generic change (for s390, or > others?)? I'm looking for an more understandable explanation what is wrong with the S390 implementation. If the page operations require the invariant I described then it is quite easy to explain the problem and understand the solution. Jason