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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 F023FECE58C for ; Mon, 7 Oct 2019 16:20:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ABADA20684 for ; Mon, 7 Oct 2019 16:20:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ABADA20684 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5F87B8E0008; Mon, 7 Oct 2019 12:20:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5824E8E0003; Mon, 7 Oct 2019 12:20:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 449A58E0008; Mon, 7 Oct 2019 12:20:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0074.hostedemail.com [216.40.44.74]) by kanga.kvack.org (Postfix) with ESMTP id 1B71F8E0003 for ; Mon, 7 Oct 2019 12:20:36 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id B4F7882437C9 for ; Mon, 7 Oct 2019 16:20:35 +0000 (UTC) X-FDA: 76017501630.09.jelly59_223adad36a928 X-HE-Tag: jelly59_223adad36a928 X-Filterd-Recvd-Size: 4806 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Mon, 7 Oct 2019 16:20:35 +0000 (UTC) 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 C2548142F; Mon, 7 Oct 2019 09:20:34 -0700 (PDT) Received: from [10.1.197.21] (unknown [10.1.197.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1EFC43F68E; Mon, 7 Oct 2019 09:20:32 -0700 (PDT) Subject: Re: [PATCH v11 14/22] mm: pagewalk: Add 'depth' parameter to pte_hole To: Jason Gunthorpe Cc: Mark Rutland , x86@kernel.org, Arnd Bergmann , Ard Biesheuvel , Peter Zijlstra , Catalin Marinas , Dave Hansen , 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 , Will Deacon , Andrew Morton , linux-arm-kernel@lists.infradead.org, "Liang, Kan" References: <20191007153822.16518-1-steven.price@arm.com> <20191007153822.16518-15-steven.price@arm.com> <20191007161049.GA13229@ziepe.ca> From: Steven Price Message-ID: <6e570d6d-b29f-f4cb-1eb9-6ff6cab15a2e@arm.com> Date: Mon, 7 Oct 2019 17:20:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191007161049.GA13229@ziepe.ca> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit 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 07/10/2019 17:10, Jason Gunthorpe wrote: > On Mon, Oct 07, 2019 at 04:38:14PM +0100, Steven Price wrote: >> diff --git a/mm/hmm.c b/mm/hmm.c >> index 902f5fa6bf93..34fe904dd417 100644 >> +++ b/mm/hmm.c >> @@ -376,7 +376,7 @@ static void hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk, >> } >> >> static int hmm_vma_walk_hole(unsigned long addr, unsigned long end, >> - struct mm_walk *walk) >> + __always_unused int depth, struct mm_walk *walk) > > It this __always_unused on function arguments something we are doing > now? $ git grep __always_unused | wc -l 191 It's elsewhere in the kernel tree. It seems like a good way of both documenting and silencing compiler warnings. But I'm open to other suggestions. > Can we have negative depth? Should it be unsigned? As per the documentation added in this patch: * @pte_hole: if set, called for each hole at all levels, * depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD * 4:PTE. Any folded depths (where PTRS_PER_P?D is equal * to 1) are skipped. So it's signed to allow "-1" in the cases where pte_hole is called without knowing the actual depth. This is used in the function walk_page_test() because it don't walk the actual page tables, but is called on a VMA instead. This means that there may not be a single depth for the range provided. Steve >> { >> struct hmm_vma_walk *hmm_vma_walk = walk->private; >> struct hmm_range *range = hmm_vma_walk->range; >> @@ -564,7 +564,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, >> again: >> pmd = READ_ONCE(*pmdp); >> if (pmd_none(pmd)) >> - return hmm_vma_walk_hole(start, end, walk); >> + return hmm_vma_walk_hole(start, end, 0, walk); >> >> if (thp_migration_supported() && is_pmd_migration_entry(pmd)) { >> bool fault, write_fault; >> @@ -666,7 +666,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, >> again: >> pud = READ_ONCE(*pudp); >> if (pud_none(pud)) >> - return hmm_vma_walk_hole(start, end, walk); >> + return hmm_vma_walk_hole(start, end, 0, walk); >> >> if (pud_huge(pud) && pud_devmap(pud)) { >> unsigned long i, npages, pfn; >> @@ -674,7 +674,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, >> bool fault, write_fault; >> >> if (!pud_present(pud)) >> - return hmm_vma_walk_hole(start, end, walk); >> + return hmm_vma_walk_hole(start, end, 0, walk); >> >> i = (addr - range->start) >> PAGE_SHIFT; >> npages = (end - addr) >> PAGE_SHIFT; > > Otherwise this mechanical change to hmm.c looks OK to me > > Jason > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >