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bh=G8k+wf8sxRtAbSVAFMjynOWx4nhCOUiQl5JR82uclTA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pAgcGKUFPcmqcSGKzUfH7nLwJKsdSljWyGBHIdKx+8b8fUDXYywKAnnv1cjrSYsiG Ertxa4ZqReOgzsGxkJsZrto/EoLahijks7RmJHy2Ou97NaTkJN7j4K59/bLN7zdhkd 6/RmOE3X3nlyjferzBy6Ln/oVRuJLouqFvEzMRto= Message-ID: <37a7e502-ac1d-4573-a877-23b1bfd07238@arm.com> Date: Fri, 10 Apr 2026 11:00:24 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC V1 08/16] arm64/mm: Convert READ_ONCE() as pgdp_get() while accessing PGD To: "David Hildenbrand (Arm)" , linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Lorenzo Stoakes , Andrew Morton , Mike Rapoport , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com References: <20260224051153.3150613-1-anshuman.khandual@arm.com> <20260224051153.3150613-9-anshuman.khandual@arm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Stat-Signature: 67wi9mze34p6icdbt99h3edpki8hqe63 X-Rspamd-Queue-Id: A1CD7A000B X-Rspam-User: X-HE-Tag: 1775799032-413280 X-HE-Meta: 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 2qN04DWq 0FlPmmQp7jwZPYRaAZfIiAvQzhPgXtCs7XkurVnqyhTCX/hfIpdhEAjy6aQaGiS2orlmGo2RhmXyJRRs6T2GQd5H7sSuiilV4pXemNdIpmx/RJF7f0CNavgtmk+6dxXZS+AXD3IJ3IrrShBXwFD9V1QnFRWfzAyECS0l4i9+RzjIm4b94H3ErqVhtK9RGyR0qmgT076C8l750Uqf+PuniYipPO7kgif0Vboz9mtRPqI7SRUWOeluOLiNCQWpXH0kc/5M06+5hgwl43m/lNaLryiksp/ohrHPOhqPzHXOIJSRSrQmdxtgHenm1fA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 08/04/26 5:49 PM, David Hildenbrand (Arm) wrote: > On 2/24/26 06:11, Anshuman Khandual wrote: >> Convert all READ_ONCE() based PGD accesses as pgdp_get() instead which will >> support both D64 and D128 translation regime going forward. > > Please mention here why you move p4d_offset_phys/p4d_offset. (same > applies to other patches) Will do that. > > Do we get additional function calls that might degrade some page table > walkers? Sorry did not get it. Are you asking if D128 adds new page table function paths thus increasing memory access latency etc ? > > Same comment regarding BUG_ON. > As mentioned earlier it might be better to have a separate change converting similar BUG_ON() in various arm64 page table helpers.