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[217.140.101.70]) by mx.google.com with ESMTP id u25si4210247ejt.173.2019.06.04.07.24.10 for ; Tue, 04 Jun 2019 07:24:11 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1A289341; Tue, 4 Jun 2019 07:24:10 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B86483F690; Tue, 4 Jun 2019 07:24:08 -0700 (PDT) Date: Tue, 4 Jun 2019 15:24:06 +0100 From: Catalin Marinas To: Anshuman Khandual Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, Will Deacon , Mark Rutland , James Morse , Robin Murphy Subject: Re: [PATCH V3 2/2] arm64/mm: Change offset base address in [pud|pmd]_free_[pmd|pte]_page() Message-ID: <20190604142405.GI6610@arrakis.emea.arm.com> References: <1557377177-20695-1-git-send-email-anshuman.khandual@arm.com> <1557377177-20695-3-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1557377177-20695-3-git-send-email-anshuman.khandual@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Thu, May 09, 2019 at 10:16:17AM +0530, Anshuman Khandual wrote: > Pgtable page address can be fetched with [pmd|pte]_offset_[kernel] if input > address is PMD_SIZE or PTE_SIZE aligned. Input address is now guaranteed to > be aligned, hence fetched pgtable page address is always correct. But using > 0UL as offset base address has been a standard practice across platforms. > It also makes more sense as it isolates pgtable page address computation > from input virtual address alignment. This does not change functionality. > > Signed-off-by: Anshuman Khandual > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Mark Rutland > Cc: James Morse > Cc: Robin Murphy > --- > arch/arm64/mm/mmu.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index e97f018ff740..71bcb783aace 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1005,7 +1005,7 @@ int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr) > return 1; > } > > - table = pte_offset_kernel(pmdp, addr); > + table = pte_offset_kernel(pmdp, 0UL); > pmd_clear(pmdp); > __flush_tlb_kernel_pgtable(addr); > pte_free_kernel(NULL, table); > @@ -1026,8 +1026,8 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr) > return 1; > } > > - table = pmd_offset(pudp, addr); > - pmdp = table; > + table = pmd_offset(pudp, 0UL); > + pmdp = pmd_offset(pudp, addr); > next = addr; > end = addr + PUD_SIZE; > do { I have the same comment as last time: https://lore.kernel.org/linux-arm-kernel/20190430161759.GI29799@arrakis.emea.arm.com/ I don't see why pmdp needs to be different from table. We get the pointer to a pmd page and we want to iterate over it to free the pte entries it contains. You can add a VM_WARN on addr alignment as in the previous version of the patch but pmdp is just an iterator over table. -- Catalin