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 60CA441D11E for ; Mon, 12 Oct 2026 11:04:16 +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=1791803058; cv=none; b=Fe8Q9vooqNscrtDaYKG1aGwX46Ls69QWFAodsnUtxbTJFIC7KZby+51f83n4JnozGBP6FFJ7OMii0hp+SQqh6qVT8uE7mh9XdbW76sieW2l0zOCVgiYWCw/6HgDTa/PTEibu+xC2KxeNr4C2x45jOsDM4S/Gs4Gbg5cY5BSewWI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791803058; c=relaxed/simple; bh=GCUhwqR9gUHDDQkSnLEoqzzvzh0xq7rUr9tQxJpA+Tk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YbawUdINCuMi8ybEqj116A8aIqnGYowOy/oZqQYHgYGU7nxgfdExcL8fW0Bwvdb5lgsFebncmqF/et53ZLOfPQZOZk7WJBnlHwzDKjSJsvc1qJ2EaQuxbslDfi4RkX2fV0DPdRfOErOHITk1fLtDg4x/SpblFF+9wl/FclOtDTI= 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; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=F++r00nm; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="F++r00nm" 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 5F2BB1A00; Mon, 12 Oct 2026 04:04:12 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 196FF3F882; Mon, 12 Oct 2026 04:04:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791803055; bh=GCUhwqR9gUHDDQkSnLEoqzzvzh0xq7rUr9tQxJpA+Tk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=F++r00nmSoucDHHIsuKWsEv8xVrypp0HtBNdtRJkDKmLkBuJP64zRrb/xJIShO22H uzo9MhZARvb/XeMwbi4x6xH3NT4IvmY4wF11YylB9B5Dtu48YuFY4E4Wms0ChMknp5 vAcbnxdzzKSKleLIyoOeqv3IWqJ/z9HrDI5yVhac= Date: Mon, 12 Oct 2026 12:04:11 +0100 From: Catalin Marinas To: Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, Will Deacon , Ryan Roberts , Mark Rutland , Lorenzo Stoakes , Andrew Morton , David Hildenbrand , Mike Rapoport , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com Subject: Re: [PATCH V3 1/4] arm64/mm: Use pmdp_get() for PMD accesses Message-ID: References: <20260924062214.1635078-1-anshuman.khandual@arm.com> <20260924062214.1635078-2-anshuman.khandual@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@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 Wed, Oct 07, 2026 at 08:11:52AM +0530, Anshuman Khandual wrote: > On Mon, Oct 05, 2026 at 04:31:28PM +0100, Catalin Marinas wrote: > > On Thu, Sep 24, 2026 at 11:52:11AM +0530, Anshuman Khandual wrote: > > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > > > index 763c5a411d64..9ad2d03e86ad 100644 > > > --- a/arch/arm64/include/asm/pgtable.h > > > +++ b/arch/arm64/include/asm/pgtable.h > > > @@ -84,6 +84,12 @@ static inline void arch_leave_lazy_mmu_mode(void) > > > arch_flush_lazy_mmu_mode(); > > > } > > > > > > +#define pmdp_get pmdp_get > > > +static inline pmd_t pmdp_get(pmd_t *pmdp) > > > +{ > > > + return READ_ONCE(*pmdp); > > > +} > > > > This is the same as the generic version. Does it need redefining? > > Without this pmdp_get() override, replacing READ_ONCE() in pmdp_test_and_clear_young() > with pmdp_get() causes a build failure as pmpd_get() which is defined in the generic > pgtable header is not visible from inside platform specific pgtable header, even with > a forward declaration. > > Earlier had moved pmdp_test_and_clear_young() inside arch/arm64/mm/mmu.c to avoid the > above described dependency problem. But then realised that pmdp_get() gets eventually > overridden on arm64 platform for D128, why not just redefine here it now as standard > READ_ONCE() to avoid the current build problem and the code movement. > > Please find some context here from earlier discussions during V2. > > https://lore.kernel.org/all/212067fe-1b16-4b87-87a7-4ce50847eb24@arm.com/ Thanks for link summary of the past discussion. I agree, for D128 we'll have to define our p*d_get() but I haven't decided D128 is worth merging yet (it depends on future hardware availability, I need to get more visibility into this). For the time being, I'd keep the p*d_get() accessors generic and move pmdp_test_and_clear_young() to mmu.c. > > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > > > #define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE > > > > > > @@ -811,7 +817,8 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) > > > } > > > > > > /* Find an entry in the third-level page table. */ > > > -#define pte_offset_phys(dir,addr) (pmd_page_paddr(READ_ONCE(*(dir))) + pte_index(addr) * sizeof(pte_t)) > > > +#define pte_offset_phys(dir, addr) (pmd_page_paddr(pmdp_get(dir)) + \ > > > + pte_index(addr) * sizeof(pte_t)) > > > > Why not make this change in the generic version? > > Could you please elaborate on this ? pte_offset_phys() is arm64 specific helper which > is also local to this header file. AFAICT there is no generic version for this helper. You are right, I got confused. Anyway, I'd push this series post -rc1. It depends on the mm tree and it's getting pretty close to the merging window. -- Catalin