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From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf/events: Replace READ_ONCE() with standard pgtable accessors
Date: Tue, 7 Apr 2026 08:48:22 +0200	[thread overview]
Message-ID: <c7688962-d10c-49e1-a434-ab7ae2c64cdb@kernel.org> (raw)
In-Reply-To: <1267a6c0-f8e7-4708-96da-4d131b5c6069@arm.com>

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 <akpm@linux-foundation.org>
>> Cc: David Hildenbrand <david@kernel.org>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
>> Cc: Namhyung Kim <namhyung@kernel.org>
>> Cc: linux-perf-users@vger.kernel.org
>> Cc: linux-mm@kvack.org
>> Cc: linux-kernel@vger.kernel.org
>> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> 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.

-- 
Cheers,

David


  reply	other threads:[~2026-04-07  6:48 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-27  6:27 [PATCH] perf/events: Replace READ_ONCE() with standard pgtable accessors Anshuman Khandual
2026-02-27 20:55 ` David Hildenbrand (Arm)
2026-02-28 16:49 ` SeongJae Park
2026-03-09  3:26 ` Anshuman Khandual
2026-04-07  3:28 ` Anshuman Khandual
2026-04-07  6:48   ` David Hildenbrand (Arm) [this message]
2026-04-07  6:53     ` Anshuman Khandual
2026-04-07  7:18     ` Peter Zijlstra

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