From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CEB683112AB; Sat, 28 Feb 2026 16:50:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772297407; cv=none; b=R7RbRxWj6//2bte62v89/9ZKOF4bTm6dVXgDoE2l+QLNFmRlxehqyr3hxiqKtBppTKTjTiEIbnzvCqhoPKmZThMzoVdgJf09oOrffYZN9jLU3fV8o9SmpQWQoCA04mnxAaBPM9XA1ZwKvwbrjS65K1Zhk+yjZmDu069CYGWVfak= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772297407; c=relaxed/simple; bh=EKQhU9MFTHfsLUytyRShr1nIh18ZLFNPpAoVEawueIo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Hn4ZzJsIlPHE45HTD+KA/wjZ+ZyyajH68RqrMlHw6KKj7cM1JzYNRfFKXe341k37GiGD/FhwJmn7wbivITnTFOU/MpqvYLuwxN3zRy+BcrWGlOPq2FacvgGuDgiEj48DHHQbdtdAjWXmO631uH05EeuU68pYVdo/sAs90NWjOjE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FYw9u4Jy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FYw9u4Jy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45306C116D0; Sat, 28 Feb 2026 16:50:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772297407; bh=EKQhU9MFTHfsLUytyRShr1nIh18ZLFNPpAoVEawueIo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FYw9u4JyY6IrjZ+viPaZhpv445h12H08bmsKim9gDxQEEoQBx1U/lWp+6b2wsU7VY /J2vJyAfpJTNB1U+Fu66WudIsqY6Pu51sgPNtYLjNThG4MhY4d0cmCh8PGbhTAliE7 hIezCvoesoIVE6+xRk5gSX8tCRdr7ESRj92vazq8WMApe20OPqUZkj367zixcGYMrg iXcwnX33D7XigvEo5XXl7wzg6mtV3bD/FFmz2q/Qfd9mjZ5b9zJsUIOxZI+gjguYJF /wdgME4lFkmzdiT4CSFba0bE78J276XhXpsTTKJ6Uu/5Hz/cSHcfASvav0Ov6OoqNG 2IyKmtuqiDysA== From: SeongJae Park To: Anshuman Khandual Cc: SeongJae Park , linux-mm@kvack.org, Andrew Morton , David Hildenbrand , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf/events: Replace READ_ONCE() with standard pgtable accessors Date: Sat, 28 Feb 2026 08:49:58 -0800 Message-ID: <20260228164959.39672-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260227062744.2215491-1-anshuman.khandual@arm.com> References: Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Fri, 27 Feb 2026 06:27:44 +0000 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 Acked-by: SeongJae Park Thanks, SJ [...]