From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BB0B41397; Thu, 9 Oct 2025 02:03:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759975394; cv=none; b=R+C/QkF38p6ZMDHOaA1cTK3S9K6+9xIiH6yBny3bgvBCF+GtFOByCMUPSII8AWOk7aBmPCQ0uEHOGX2qfuh4Fys1+Gy0waiPxME3SdQ8G1I5ZwMnExuynUNzsK8DcFJfAZuaeQ/K5Ew1YUUzo7aBcjScir47rk1TmRb6ztQiD8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759975394; c=relaxed/simple; bh=FYeKjXCSa+sugLZNOvMXe+AcFfKj2MNmosBD05Z/05g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=t087YLUUKXhLORZBdeovZlP9FdjrmuA1NBF5QI9x7Vvx4iGjuV8smIdincY/xJ1GRNK6SdF82xqBZNTzRxXmGdhEn+Sncaem6BCI2w7816p6dmM4E62WpVoEiMAJEbmgjhaBrlyxIMam3QVludhGlrxvIYpN9MrwYO/4yvwv5Gc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C5AFA1A32; Wed, 8 Oct 2025 19:03:02 -0700 (PDT) Received: from [10.163.35.84] (unknown [10.163.35.84]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E94173F738; Wed, 8 Oct 2025 19:03:06 -0700 (PDT) Message-ID: <24beaa64-d144-42c3-945f-a37e1cac384d@arm.com> Date: Thu, 9 Oct 2025 07:33:03 +0530 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 02/18] perf/core: Replace READ_ONCE() with standard page table accessors To: Samuel Holland , Palmer Dabbelt , Paul Walmsley , linux-riscv@lists.infradead.org Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Conor Dooley , Alexandre Ghiti , Emil Renner Berthing , Andrew Morton , Rob Herring , Krzysztof Kozlowski References: <20251009015839.3460231-1-samuel.holland@sifive.com> <20251009015839.3460231-3-samuel.holland@sifive.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <20251009015839.3460231-3-samuel.holland@sifive.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 09/10/25 7:27 AM, Samuel Holland wrote: > Replace READ_ONCE() with standard page table accessors, i.e. pXXp_get(), > which have a default implementation of READ_ONCE() if the architecture > does not override them. > > Signed-off-by: Samuel Holland > --- > > Changes in v2: > - New patch for v2 > > kernel/events/core.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 820127536e62b..952ba4e3d8815 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -8110,7 +8110,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr) > pte_t *ptep, pte; > > pgdp = pgd_offset(mm, addr); > - pgd = READ_ONCE(*pgdp); > + pgd = pgdp_get(pgdp); > if (pgd_none(pgd)) > return 0; > > @@ -8118,7 +8118,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr) > return pgd_leaf_size(pgd); > > p4dp = p4d_offset_lockless(pgdp, pgd, addr); > - p4d = READ_ONCE(*p4dp); > + p4d = p4dp_get(p4dp); > if (!p4d_present(p4d)) > return 0; > > @@ -8126,7 +8126,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr) > return p4d_leaf_size(p4d); > > pudp = pud_offset_lockless(p4dp, p4d, addr); > - pud = READ_ONCE(*pudp); > + pud = pudp_get(pudp); > if (!pud_present(pud)) > return 0; > This is already under discussion here. https://lore.kernel.org/all/20251006042622.1743675-1-anshuman.khandual@arm.com/