From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A08C4C43381 for ; Fri, 22 Mar 2019 10:12:18 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6F272218D3 for ; Fri, 22 Mar 2019 10:12:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="g3RCDbBp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F272218D3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=U3IHe6UOmSYo1wEKZ11zmZZNFia26jqLwJuYkYI/Zrc=; b=g3RCDbBpJBx2uI rEDJRSx7mcFBoCtiyACjTLJbCPeZKwDn+2xfVgFMYd/Fh60fbDCUn01jmXm/NSaTbdW4yp5y42AQM 97QZpJKXKjquJtcWds8+11K/1hK4MFk0srHFi8VBKXer097yOyTUXj3F8dNtXjBU77OMH1mDsNoNL gj+7LHKkcXx2Xqo23dosFx5JfqoswlzgZAvwtzVvfMZNV8447d2vkCMxG5wJtI9og8IC7+Oi9N8Rw 8XlUFMfDm9NrpZW7wyMu8xzHazDecuVe84a6g6DGlalZqS+Hp6OYfWqk3f8Qujl/YbNsqdqAHq3wy u2RNZ/8Q0GM2jJWQcrzw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h7H9n-00022I-Oi; Fri, 22 Mar 2019 10:12:11 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h7H9g-00021A-At for linux-arm-kernel@lists.infradead.org; Fri, 22 Mar 2019 10:12:09 +0000 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 E6E79374; Fri, 22 Mar 2019 03:12:03 -0700 (PDT) Received: from [10.1.196.69] (e112269-lin.cambridge.arm.com [10.1.196.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C869E3F575; Fri, 22 Mar 2019 03:12:00 -0700 (PDT) Subject: Re: [PATCH v5 10/19] mm: pagewalk: Add p4d_entry() and pgd_entry() To: Mike Rapoport References: <20190321141953.31960-1-steven.price@arm.com> <20190321141953.31960-11-steven.price@arm.com> <20190321211510.GA27213@rapoport-lnx> From: Steven Price Message-ID: <03f5ad0f-2450-c53f-b1e6-d2c0f2d4879c@arm.com> Date: Fri, 22 Mar 2019 10:11:59 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190321211510.GA27213@rapoport-lnx> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190322_031207_816322_E612F38B X-CRM114-Status: GOOD ( 22.24 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Dave Hansen , Arnd Bergmann , Ard Biesheuvel , Peter Zijlstra , Catalin Marinas , x86@kernel.org, Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Ingo Molnar , Borislav Petkov , Andy Lutomirski , "H. Peter Anvin" , James Morse , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, "Liang, Kan" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 21/03/2019 21:15, Mike Rapoport wrote: > On Thu, Mar 21, 2019 at 02:19:44PM +0000, Steven Price wrote: >> pgd_entry() and pud_entry() were removed by commit 0b1fbfe50006c410 >> ("mm/pagewalk: remove pgd_entry() and pud_entry()") because there were >> no users. We're about to add users so reintroduce them, along with >> p4d_entry() as we now have 5 levels of tables. >> >> Note that commit a00cc7d9dd93d66a ("mm, x86: add support for >> PUD-sized transparent hugepages") already re-added pud_entry() but with >> different semantics to the other callbacks. Since there have never >> been upstream users of this, revert the semantics back to match the >> other callbacks. This means pud_entry() is called for all entries, not >> just transparent huge pages. >> >> Signed-off-by: Steven Price >> --- >> include/linux/mm.h | 9 ++++++--- >> mm/pagewalk.c | 27 ++++++++++++++++----------- >> 2 files changed, 22 insertions(+), 14 deletions(-) >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 76769749b5a5..2983f2396a72 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -1367,10 +1367,9 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma, >> >> /** >> * mm_walk - callbacks for walk_page_range >> + * @pgd_entry: if set, called for each non-empty PGD (top-level) entry >> + * @p4d_entry: if set, called for each non-empty P4D (1st-level) entry > > IMHO, p4d implies the 4th level :) You have a good point there... I was simply working back from the existing definitions (below) of PTE:4th, PMD:3rd, PUD:2nd. But it's already somewhat broken by PGD:0th and my cop-out was calling it "top". > I think it would make more sense to start counting from PTE rather than > from PGD. Then it would be consistent across architectures with fewer > levels. It would also be the opposite way round to architectures such as Arm which number their levels, for example [1] refers to levels 0-3 (with 3 being PTE in Linux terms). [1] https://developer.arm.com/docs/100940/latest/translation-tables-in-armv8-a Probably the least confusing thing is to drop the level numbers in brackets since I don't believe they directly match any architecture, and hopefully any user of the page walking code is already familiar with the P?D terms used by the kernel. Steve >> * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry >> - * this handler should only handle pud_trans_huge() puds. >> - * the pmd_entry or pte_entry callbacks will be used for >> - * regular PUDs. >> * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry >> * this handler is required to be able to handle >> * pmd_trans_huge() pmds. They may simply choose to >> @@ -1390,6 +1389,10 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma, >> * (see the comment on walk_page_range() for more details) >> */ >> struct mm_walk { >> + int (*pgd_entry)(pgd_t *pgd, unsigned long addr, >> + unsigned long next, struct mm_walk *walk); >> + int (*p4d_entry)(p4d_t *p4d, unsigned long addr, >> + unsigned long next, struct mm_walk *walk); >> int (*pud_entry)(pud_t *pud, unsigned long addr, >> unsigned long next, struct mm_walk *walk); >> int (*pmd_entry)(pmd_t *pmd, unsigned long addr, >> diff --git a/mm/pagewalk.c b/mm/pagewalk.c >> index c3084ff2569d..98373a9f88b8 100644 >> --- a/mm/pagewalk.c >> +++ b/mm/pagewalk.c >> @@ -90,15 +90,9 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, >> } >> >> if (walk->pud_entry) { >> - spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma); >> - >> - if (ptl) { >> - err = walk->pud_entry(pud, addr, next, walk); >> - spin_unlock(ptl); >> - if (err) >> - break; >> - continue; >> - } >> + err = walk->pud_entry(pud, addr, next, walk); >> + if (err) >> + break; >> } >> >> split_huge_pud(walk->vma, pud, addr); >> @@ -131,7 +125,12 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, >> break; >> continue; >> } >> - if (walk->pmd_entry || walk->pte_entry) >> + if (walk->p4d_entry) { >> + err = walk->p4d_entry(p4d, addr, next, walk); >> + if (err) >> + break; >> + } >> + if (walk->pud_entry || walk->pmd_entry || walk->pte_entry) >> err = walk_pud_range(p4d, addr, next, walk); >> if (err) >> break; >> @@ -157,7 +156,13 @@ static int walk_pgd_range(unsigned long addr, unsigned long end, >> break; >> continue; >> } >> - if (walk->pmd_entry || walk->pte_entry) >> + if (walk->pgd_entry) { >> + err = walk->pgd_entry(pgd, addr, next, walk); >> + if (err) >> + break; >> + } >> + if (walk->p4d_entry || walk->pud_entry || walk->pmd_entry || >> + walk->pte_entry) >> err = walk_p4d_range(pgd, addr, next, walk); >> if (err) >> break; >> -- >> 2.20.1 >> > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel