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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 659ACC3DA70 for ; Tue, 30 Jul 2024 16:10:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ED2436B008A; Tue, 30 Jul 2024 12:10:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E82246B008C; Tue, 30 Jul 2024 12:10:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CFC976B0092; Tue, 30 Jul 2024 12:10:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id AF0D86B008A for ; Tue, 30 Jul 2024 12:10:47 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 127981A03AB for ; Tue, 30 Jul 2024 16:10:47 +0000 (UTC) X-FDA: 82396907334.20.C0ADD4D Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf08.hostedemail.com (Postfix) with ESMTP id BF9F616002E for ; Tue, 30 Jul 2024 16:10:44 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Z4tgTNeG; spf=pass (imf08.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1722355840; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=LjzRi7jALKxQVLT6IAeQ2Kw7/y58JXdmAZC1XNdJlT8=; b=ilYX7lXn6OM7Ycpu2PXha11Ofa1aOSKDT6+WLx/Cvs32Fya/srWjxT4Hlcr2Rkl9rvAB+j sWaSVJcpr5fs7D3CCp5Z5NDa0VaD7a6pbeiicK8oaPnpMTrRN/r4gvzry3o4Bkb2Olk/gH +0hgPpoUw2E+yaHNrk1zPP2zy8120Nc= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Z4tgTNeG; spf=pass (imf08.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1722355840; a=rsa-sha256; cv=none; b=HTRmXINBSDRh2ib35djuDJkjK0MRnDiPp9FAUZUXHr4vzRuuj8VzgqKldr762GRtQMfRB3 XuEnBAi+TYNInObdIpXBquvn7bLnWX542B0nTZIBXZEWmKda2GKwMquOIExmW/85bjAiUy /JbJPtrfUK6Y3BwVxU30Whvt/Tx8YzQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722355844; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=LjzRi7jALKxQVLT6IAeQ2Kw7/y58JXdmAZC1XNdJlT8=; b=Z4tgTNeGkAx8lFqo/Gce1+junXTANzjpBRF2kk1+/iLq/5lA2Sadm+EfG/tjY23L7vJh+1 g2A34vVWI4w4L3BDkvw1DZ6uc7MWzWgOewm6AzjMjdR3PqI1vBOkBa9ugfKv6PL49ac+nm 2OOWSbFSN9t8OSPq8+dPPopewU65rLQ= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-534-7Z7nZqltPI6FwUmkfp7xiw-1; Tue, 30 Jul 2024 12:10:40 -0400 X-MC-Unique: 7Z7nZqltPI6FwUmkfp7xiw-1 Received: by mail-wr1-f72.google.com with SMTP id ffacd0b85a97d-3687eca5980so2140072f8f.0 for ; Tue, 30 Jul 2024 09:10:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722355839; x=1722960639; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=LjzRi7jALKxQVLT6IAeQ2Kw7/y58JXdmAZC1XNdJlT8=; b=kSkcpdmIqgNugXyWDUEjCaUvOoDwxeoxin6QVZBnstE1gOF+QELg2w8ZT8/BvYb5Gs bncvdhG1KenS2iWFHCtq+L6P1OQDQPJfImyElpdatKXFtOyZByELmZUPgbZvTeJGTdPl XkDaQY6BPVAPUo5IMLYeYk24excyLqWi8AXJXQcFfincJML9thim8ldNFYK7F8B47+1G jRUrDa1z8YbKBhT33tEJGLbsqgR80rulgYzm0YSwJJZQ3An3IFbqlOeDX7kpM3DKIKUg JLeXA3oot1PhWtrCx9jghhay1iSOzTTPJ4wvZ9hDHh/IyAOlsDzxRdRzlavsO8Qtb8mY j4Hg== X-Gm-Message-State: AOJu0YzaJklPrr8nVurlzdDNi93vMLiOiwl0dOSyvE++Wpfv2Ze15udU axnjiMceleoonIKORIe8JcdBpVrBdA5EDPIpKMYZ35pH/TeP2f7UHt0/mBNesVDc6Td37tT9Vod ZozR3P+zfW1jxGmlEFtQloOksEaBznc8YIhnDbAv3iisTRybO X-Received: by 2002:adf:e808:0:b0:367:947a:a491 with SMTP id ffacd0b85a97d-36b5d0d0e60mr7156428f8f.26.1722355839163; Tue, 30 Jul 2024 09:10:39 -0700 (PDT) X-Google-Smtp-Source: AGHT+IELDw6dDJdDxPdi4lco05Z7I9XwKxX9IxtEP8Vvmz7Lk0HH5JihFo4vZFKdHBZLB1Ehkngjfw== X-Received: by 2002:adf:e808:0:b0:367:947a:a491 with SMTP id ffacd0b85a97d-36b5d0d0e60mr7156410f8f.26.1722355838754; Tue, 30 Jul 2024 09:10:38 -0700 (PDT) Received: from ?IPV6:2003:cb:c706:4e00:31ad:5274:e21c:b59? (p200300cbc7064e0031ad5274e21c0b59.dip0.t-ipconnect.de. [2003:cb:c706:4e00:31ad:5274:e21c:b59]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36b367d9a3asm14833729f8f.36.2024.07.30.09.10.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jul 2024 09:10:38 -0700 (PDT) Message-ID: Date: Tue, 30 Jul 2024 18:10:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/2] mm: let pte_lockptr() consume a pte_t pointer To: Marek Szyprowski , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Muchun Song , Peter Xu , Oscar Salvador References: <20240725183955.2268884-1-david@redhat.com> <20240725183955.2268884-2-david@redhat.com> <97d87df8-6076-4df0-90a9-a8f5ddea42e9@samsung.com> <82e77547-5116-4ef2-a232-f5ab1fca7e02@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: qy8q7wimtnw7kwjjpkhkbhic7ojkugu5 X-Rspamd-Queue-Id: BF9F616002E X-Rspamd-Server: rspam11 X-HE-Tag: 1722355844-138952 X-HE-Meta: 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 JHpN3XY/ QbGv01KISzEGxK1/5ibsBJ5qn1ljeglKwS+X5puXO6BGW1OlzF3E3VjI0TP+/iTSg6nBD8lefb0F6zK1KeukRLc5wZCkC8to/WVm8WnwTj2mDF7p6HipfoFkZSQ3jgdjOqNpvd5fryGW9X6K2jsYAKA69DFubRVUB27PohPzx1cv6wl9uGnYvahSBXd8nPyTJWbbe2H1Ced4qG33PeQh5p5i9zKCdWFWGzC844XaxFNytL5ess9IWoVweNPi9IF0DWZD8bmuGk1J73sp43SwxwhGyaD6WhV/CXYym0Ri0E9klu3JOlYBGZbivPj5G7oyHvtGrPbg90YB4p/qzUY27O/ulGQkiP5X37NMBeniSECduN+eTjsWqdBBttj2BFi3FS0gn69y09/nAQqDZroItyf06KnGxSPMmtCweVrn88tYmUYNj4ruNgRKnVm1BEgqCpn8ksR1lxraWCCn5f+ELjgoD9g== 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 30.07.24 18:08, Marek Szyprowski wrote: > On 30.07.2024 17:49, David Hildenbrand wrote: >> On 30.07.24 17:45, David Hildenbrand wrote: >>> On 30.07.24 17:30, Marek Szyprowski wrote: >>>> On 25.07.2024 20:39, David Hildenbrand wrote: >>>>> pte_lockptr() is the only *_lockptr() function that doesn't consume >>>>> what would be expected: it consumes a pmd_t pointer instead of a pte_t >>>>> pointer. >>>>> >>>>> Let's change that. The two callers in pgtable-generic.c are easily >>>>> adjusted. Adjust khugepaged.c:retract_page_tables() to simply do a >>>>> pte_offset_map_nolock() to obtain the lock, even though we won't >>>>> actually >>>>> be traversing the page table. >>>>> >>>>> This makes the code more similar to the other variants and avoids >>>>> other >>>>> hacks to make the new pte_lockptr() version happy. pte_lockptr() users >>>>> reside now only in  pgtable-generic.c. >>>>> >>>>> Maybe, using pte_offset_map_nolock() is the right thing to do because >>>>> the PTE table could have been removed in the meantime? At least it >>>>> sounds >>>>> more future proof if we ever have other means of page table reclaim. >>>>> >>>>> It's not quite clear if holding the PTE table lock is really required: >>>>> what if someone else obtains the lock just after we unlock it? But >>>>> we'll >>>>> leave that as is for now, maybe there are good reasons. >>>>> >>>>> This is a preparation for adapting hugetlb page table locking logic to >>>>> take the same locks as core-mm page table walkers would. >>>>> >>>>> Signed-off-by: David Hildenbrand >>>> >>>> This patch landed in today's linux-next as commit e98970a1d2d4 ("mm: >>>> let >>>> pte_lockptr() consume a pte_t pointer"). Unfortunately it causes the >>>> following issue on most of my ARM 32bit based test boards: >>>> >>> >>> That is ... rather surprising. >>> >>> The issue below seems to point at __pte_offset_map_lock(), where we >>> essentially convert from >>> >>> ptlock_ptr(page_ptdesc(pmd_page(*pmd))); >>> >>> to >>> >>> ptlock_ptr(virt_to_ptdesc(pte)); >> >> I'm wondering, is highmem involved here such that the PTE would be >> kmap'ed and virt_to_page() would not do what we would expect it to do? > > Yes, highmem is enabled on those boards and all of them have 1GB+ of > RAM. For other kernel configuration options see > arch/arm/configs/exynos_defconfig. Yes, pretty sure that's it. virt_to_page() won't work on kmaped pages. So looks like we cannot easily do the conversion in this patch. :( We'll have to get hacky in patch #2 instead. @Andrew, can you drop both patches for now? I'll send a v2 that essentially does in v2 on top something like: diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index da800e56fe590..c2e330b1eee21 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -963,7 +963,13 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h, * will give us the same result: the per-MM PT lock. */ if (huge_page_size(h) < PMD_SIZE) - return pte_lockptr(mm, pte); + /* + * pte_lockptr() needs the PMD, which we don't have. Because of + * highmem we cannot convert pte_lockptr() to consume a pte. + * But as we never have highmem page tables in hugetlb, we can + * safely use virt_to_ptdesc() here. + */ + return ptlock_ptr(virt_to_ptdesc(pte)); else if (huge_page_size(h) < PUD_SIZE) return pmd_lockptr(mm, (pmd_t *) pte); return pud_lockptr(mm, (pud_t *) pte); -- Cheers, David / dhildenb