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bh=rvCB0mtFCTChcch/FM64LYIf0vr0IZ0WwJBCN05cnQg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ZSPo+kwjikI+iRW4adeq1Vx/UxwAGFrfNhig45c90krMMeJUQpomGNau9pTkioJg3 mzGBxrK+v+q1P5KG9fHhUFQbVCAaYZnRtbR6gS4JFEchs1JRDpB3ykj9MtEMsAjDi7 VnrqcD848OeDpenFRsURVEewmf1UU4/17K4SfAjM= Message-ID: Date: Wed, 8 Apr 2026 16:28:48 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] perf/events: Replace READ_ONCE() with standard pgtable accessors To: Peter Zijlstra , "David Hildenbrand (Arm)" Cc: linux-mm@kvack.org, Andrew Morton , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260227062744.2215491-1-anshuman.khandual@arm.com> <1267a6c0-f8e7-4708-96da-4d131b5c6069@arm.com> <20260407071820.GA3738010@noisy.programming.kicks-ass.net> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <20260407071820.GA3738010@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B2B6A120008 X-Stat-Signature: m5i953ibn17fcjw3rgwk6b96y4jz6mao X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1775645935-194570 X-HE-Meta: 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 jPibWXkh 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 07/04/26 12:48 PM, Peter Zijlstra wrote: > On Tue, Apr 07, 2026 at 08:48:22AM +0200, David Hildenbrand (Arm) wrote: >> On 4/7/26 05:28, Anshuman Khandual wrote: >>> >>> >>> On 27/02/26 11:57 AM, Anshuman Khandual wrote: >>>> Replace raw READ_ONCE() dereferences of pgtable entries with corresponding >>>> standard page table accessors pxdp_get() in perf_get_pgtable_size(). These >>>> accessors default to READ_ONCE() on platforms that don't override them. So >>>> there is no functional change on such platforms. >>>> >>>> However arm64 platform is being extended to support 128 bit page tables via >>>> a new architecture feature i.e FEAT_D128 in which case READ_ONCE() will not >>>> provide required single copy atomic access for 128 bit page table entries. >>>> Although pxdp_get() accessors can later be overridden on arm64 platform to >>>> extend required single copy atomicity support on 128 bit entries. >>>> >>>> Cc: Andrew Morton >>>> Cc: David Hildenbrand >>>> Cc: Peter Zijlstra >>>> Cc: Ingo Molnar >>>> Cc: Arnaldo Carvalho de Melo >>>> Cc: Namhyung Kim >>>> Cc: linux-perf-users@vger.kernel.org >>>> Cc: linux-mm@kvack.org >>>> Cc: linux-kernel@vger.kernel.org >>>> Acked-by: Peter Zijlstra (Intel) >>>> Signed-off-by: Anshuman Khandual >>>> --- >>>> This patch applies both on v7.0-rc1 and mm-unstable. >>>> >>>> Part of the D128 series but independent. Hence could be considered on its own. >>>> >>>> https://lore.kernel.org/all/20260224051153.3150613-5-anshuman.khandual@arm.com/ >>>> >>>> Collected Peter's tag from an off list conversation. >>> >>> Gentle ping. >>> >>> Still don't see this patch in latest next-20260406. Hence just >>> wondering which tree and branch this patch is being picked up ? >> >> It's a trivial change and the last generic code change required for you >> arm64 D128 change, right? >> >> I would assume this to go through the tip tree, but if Peter agrees we >> could route this (mm) patch through the MM tree. > > Right, I thought this was part of a larger series and figured it would > ride along with whatever other patches. > > If you still want me to pick this up, I can, just state clearly where > this ought to go. It would be great if you could pick this up. Thanks !