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Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuprD-0000000Gh6J-17U0; Tue, 24 Feb 2026 10:41:35 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0DEC930075A; Tue, 24 Feb 2026 11:41:34 +0100 (CET) Date: Tue, 24 Feb 2026 11:41:34 +0100 From: Peter Zijlstra To: Mark Rutland Cc: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Ryan Roberts , Lorenzo Stoakes , Andrew Morton , David Hildenbrand , Mike Rapoport , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , linux-perf-users@vger.kernel.org Subject: Re: [RFC V1 04/16] perf/events: Replace READ_ONCE() with standard pgtable accessors Message-ID: <20260224104134.GW1395266@noisy.programming.kicks-ass.net> References: <20260224051153.3150613-1-anshuman.khandual@arm.com> <20260224051153.3150613-5-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: BBC8F180002 X-Stat-Signature: naq77wiq5r3ybq9j1krzn1k1wotwftkh X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1771929698-603565 X-HE-Meta: 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 dXpqedyj K788+BQE7FAIoUcaoJ3O98QmqQHKBHwJHxF5+/1ymlJWEw7mwMA26SfhdepMUVykz5T2Ljkz1nEfYdzCwcIaBbse7hfAu92PWODZSESZ3s0DzH171occJ+Y2haZmThN4u9HUYcEyhoVafS1Mzcqf91j9ZqoRl3HZVJj+7yK8VYRo/SaOOT0kTN/xLIMDKSn/I9SATX5bEco2DfwtyOuHRwnF2sYvmSGl8eEAKM75MG2BwiU+8reN8OlgrS7Oa87dJDwKAxT/UAzWW6nLWUo1Gyx4cMw3u7DBb9sK0 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: List-Subscribe: List-Unsubscribe: On Tue, Feb 24, 2026 at 10:08:21AM +0000, Mark Rutland wrote: > On Tue, Feb 24, 2026 at 10:41:41AM +0530, Anshuman Khandual wrote: > > Replace READ_ONCE() with standard page table accessors i.e pxdp_get() which > > anyways default into READ_ONCE() in cases where platform do not override. > > For each of the patches where you make this sort of change, please > explain in the commit message *why* it is necessary to do this. > > IIUC the entire point of this is that in subsequent patches, arm64 will > need to use something other than READ_ONCE() for all pXX levels in order > to support D128 translation tables. > > Spelling that out in the commit message makes it much easier for > reviewers to see what's going on, and to focus any discussion/questions, > e.g. *why* won't READ_ONCE() work? That, and only being sent *one* patch, I have no clue what the rest of them are doing. Didn't even get 0/n. I hate people sending me just one patch; just send the whole series already.