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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gq19ZaG6H/Z6QLLA361dNnxs7Rcoy1FFoxh2es/ZkM34A3iiH7Q0NWkQ9Xjf85a/V Cw84yhYE9dms8niScH613/FI3ApHX6Wc/QmkYVNEjsQk3N+7VxRQ/QXYkr1v8tdtC2 iPBeGS35uCwhoz4oVnSyTerqZzVYnRL5bM3gmw1g= Message-ID: Date: Tue, 7 Apr 2026 12:23:39 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] perf/events: Replace READ_ONCE() with standard pgtable accessors To: "David Hildenbrand (Arm)" , linux-mm@kvack.org, Andrew Morton Cc: Peter Zijlstra , 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> Content-Language: en-US From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 7AE2E80002 X-Stat-Signature: hfysjao6ockseb8fitxcoowe1a55ggrp X-HE-Tag: 1775544826-804756 X-HE-Meta: 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 5kUuEIj4 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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 12:18 PM, 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? 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. > Sure