From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 22D24244692; Tue, 7 Apr 2026 07:18:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775546313; cv=none; b=QKLDb8EBMTBZzmZm3OS7grDmnU/dTkRRr5IhBBWfMmUju2cgk3WWR2llRRQfhG92WhPR5AkpphVmAq43/nxAgnMH2zNds/V8i5v4nTbN4a+ERhIsGIfjAZSEdq/vuszUj67L7iLNjhFXooYJPND0KB+zEYoYSJE/YRqctsSYRuA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775546313; c=relaxed/simple; bh=7bLXUxNlUpcYuvTrZAqMUnacIkf9w6QeTruvWULg1Xc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oQEJxVldMLx42ow2m9YC4VVDYdo7Jusi8Sma8zCpYzI68/0QcLmmCwGX063gSXBwXsifzqsXXB6eYdSgsC5GOWXN7mQDzF/nXWwbTlqSd042I8dvyA23oGD3Onm02zDBUS9kXqDthaORfCAhgKl8C9SozbCbd8I653WMT7GkOXA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=nImR+pzl; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nImR+pzl" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=NDKl0CmwVm2mvyWYjyJbm938Bi5mo/cdP0hUqRq6tEE=; b=nImR+pzlf/E+k6Ma2TQTt6jT6l 2JLKZVmBxi17iw1W/l3Ap5rhlCZD1Sc8D4LNAz+UHSJhbItR7ODULzTGUXb9Nzytd/4aEziswqZXw gPaLLGQv6i+rQKdovhwW1C42vaUPoDgcxwKtBaFFcHlCEZTRKwDRVgnvRTsLFMoCdCxaxGIkonduX S3QeDEMcyVEWErBSyZ0ptrLQy4W1OdtaXKe8rSmHZDd22q+OtGs5+VXMOZz/P7fSvk9jox/wVhCT0 dMekWcdoBdB93vT4UGHyKzaP8Iep7ySwxQGJj8vjB8snrYcT4suIoX5TaTsDWFXaUB7YmCKAa0k24 p9hFBJfw==; Received: from 2001-1c00-8d85-4b00-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:4b00:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1wA0hc-00000007kG6-3xHX; Tue, 07 Apr 2026 07:18:25 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id D7DB73005E5; Tue, 07 Apr 2026 09:18:20 +0200 (CEST) Date: Tue, 7 Apr 2026 09:18:20 +0200 From: Peter Zijlstra To: "David Hildenbrand (Arm)" Cc: Anshuman Khandual , 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 Subject: Re: [PATCH] perf/events: Replace READ_ONCE() with standard pgtable accessors Message-ID: <20260407071820.GA3738010@noisy.programming.kicks-ass.net> References: <20260227062744.2215491-1-anshuman.khandual@arm.com> <1267a6c0-f8e7-4708-96da-4d131b5c6069@arm.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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.