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s=arc-20220608; d=hostedemail.com; t=1726455145; a=rsa-sha256; cv=none; b=SCLBao6RxJ5Ri87bRcxuGi4VfVhcvfMBZ+E+ikqJp/HEUzz4rCwZAYCgBIBAKu6ing9LWF ctDSN1DamCKhbsXJEJD2LQ6/o/kCjlb+QhXGjvIIxaFH3xHiIdFwPZnBvwpd458wPQ7fDT NHnbQhStTAsATSpvZJZvpQyvceodSqw= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf13.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@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 85C611476; Sun, 15 Sep 2024 19:54:54 -0700 (PDT) Received: from [10.162.16.84] (a077893.blr.arm.com [10.162.16.84]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5DAB73F64C; Sun, 15 Sep 2024 19:54:20 -0700 (PDT) Message-ID: <9d3286bd-7ad4-4472-aa26-2fb7d166fceb@arm.com> Date: Mon, 16 Sep 2024 08:24:17 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/7] x86/mm: Drop page table entry address output from pxd_ERROR() To: Dave Hansen , linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Ryan Roberts , "Mike Rapoport (IBM)" , Arnd Bergmann , x86@kernel.org, linux-m68k@lists.linux-m68k.org, linux-fsdevel@vger.kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen References: <20240913084433.1016256-1-anshuman.khandual@arm.com> <20240913084433.1016256-3-anshuman.khandual@arm.com> <8e8a94d4-39fe-4c34-9f5d-5b347ca8fe9a@intel.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <8e8a94d4-39fe-4c34-9f5d-5b347ca8fe9a@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 1319420004 X-Stat-Signature: gh9nqgri9dgcujhpou17nfen1erhcq6j X-Rspam-User: X-HE-Tag: 1726455265-800857 X-HE-Meta: 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 MdWPUZe+ RC5QmuHntZp9bJ56JvIZ2aFbFQB921m6V23RNxtyXQuMowPDhSk/fhzrfViWXOko4wYdnFbCYOTEKIBbX89zQqWhIydxV36Hs/VnakrD7HbOqX1zAbWLvTS09GdvPrbqxIcwBRKLRkVSXNAbA9c0d2o34+Ltnb48WfN0f6XngXNrwHYlCB8OXRnM8AbfW90/zeDtQ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/13/24 22:51, Dave Hansen wrote: > On 9/13/24 01:44, Anshuman Khandual wrote: >> This drops page table entry address output from all pxd_ERROR() definitions >> which now matches with other architectures. This also prevents build issues >> while transitioning into pxdp_get() based page table entry accesses. > > Could you be a _little_ more specific than "build issues"? Is it that > you want to do: > > void pmd_clear_bad(pmd_t *pmd) > { > - pmd_ERROR(*pmd); > + pmd_ERROR(pmdp_get(pmd)); > pmd_clear(pmd); > } > > But the pmd_ERROR() macro would expand that to: > > &pmdp_get(pmd) > > which is nonsense? Yes, that's the one which fails the build with the following warning. error: lvalue required as unary '&' operand Will update the commit message with these details about the build problem. > > Having the PTEs' kernel addresses _is_ handy, but I guess they're > scrambled on most end users' systems now and anybody that's actively > debugging can just use a kprobe or something to dump the pmd_clear_bad() > argument directly. Right.