Re: [PATCH] perf/events: Replace READ_ONCE() with standard pgtable accessors

[SeongJae Park <sj@kernel.org>]

On Fri, 27 Feb 2026 06:27:44 +0000 Anshuman Khandual <anshuman.khandual@arm.com> 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>

Acked-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

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