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 1F5E2C67861 for ; Mon, 8 Apr 2024 15:13:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 639F26B007B; Mon, 8 Apr 2024 11:13:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5EA6A6B0082; Mon, 8 Apr 2024 11:13:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 463DF6B0085; Mon, 8 Apr 2024 11:13:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 288CC6B007B for ; Mon, 8 Apr 2024 11:13:38 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id A2D8D160A95 for ; Mon, 8 Apr 2024 15:13:37 +0000 (UTC) X-FDA: 81986708874.15.81F6210 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf26.hostedemail.com (Postfix) with ESMTP id 70B8F14001C for ; Mon, 8 Apr 2024 15:13:35 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=UuFyeavA; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 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=1712589215; 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=FQxnCR2hhRsqV7rjNthbeUSLOg/1ik/UqgM9Jy0S5NQ=; b=AMq2GVk6bRVNbnA5/dOTWHtdxATc38YAuo9YUYvDA+PQDbMgeaG4Gjw+fO55T9Z2vblRc8 xf5lKl5zLM9BtHtLk6MHucIM83Wu8yhkQxfe1eAzhvAAE0bUH87KxPc6HYHP+mrvMN6bO+ b0zOCYBKkT15IdHGY2sV/j2UDqe0kK8= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1712589215; a=rsa-sha256; cv=none; b=yAwuaKD4JfNSejojRzxgQcCpZPoSIOYT8Ij2mimoj7TbJ81rC/L9akuwQKkn4IiKYh529h yNgox11/FbMllXDUi5ub9ANLu0SDcaPjuCS1l43gBzENsiWQBdhQ9+f3t/IznoJYmDa097 5DSHXlbvv8dIFw4jPRdW+pTNtTqQnEo= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=UuFyeavA; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712589214; 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=FQxnCR2hhRsqV7rjNthbeUSLOg/1ik/UqgM9Jy0S5NQ=; b=UuFyeavAVWsswsnh2Th/HiAaigC5Rl47NBO2GSroPnhPTCX9urbfKecQPIBt3jJll5aAil jHJDoLHIOcqlFDNLzc4rSWGpPg8X77F3ue/xv4hYjuZTiL0gDvRwKyM3ug3aJq6UG/nL7j XKJQLL8QvBvB008xXFA+SqN9go9Q+/M= Received: from mail-lj1-f198.google.com (mail-lj1-f198.google.com [209.85.208.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-283-ZCKzoSIfNSiUvdemE4gCfA-1; Mon, 08 Apr 2024 11:13:32 -0400 X-MC-Unique: ZCKzoSIfNSiUvdemE4gCfA-1 Received: by mail-lj1-f198.google.com with SMTP id 38308e7fff4ca-2d85b4ca694so35962161fa.1 for ; Mon, 08 Apr 2024 08:13:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712589211; x=1713194011; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from: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=FQxnCR2hhRsqV7rjNthbeUSLOg/1ik/UqgM9Jy0S5NQ=; b=vG6atYZesdnfsnVbsSeV6NzaSQ8niJo5+iXkfTMn3qQ6O3dyLxWAf5US7fgfO4qy7v ffq2pgLzi4Gu00GPjrsgv8KUuUsByVjhXrlSfpTNmNP5W3C5ZmD4NZhYNe6MtHIBferc iHIklPDU5y0GXmVZkfuVTzf9dKjdkfx+zStzeS/z6tMnI/48jk7UW9GZs86yGTKxx8gN 72plubI2/9TQC85GjImCchZJOWs8i4aoQ9mJRIVjADfJ6xb3YnFIIH0IQ8bIyqHzv+go iZnCaOd5gblJ3CIV5pO7UzBrfrDriaKzAk/udn/gpOng5YEK94FQocTN3C/LDfkksVZY nI/Q== X-Gm-Message-State: AOJu0Yw6rOnuqJi4FVMuyaMgdWpVqbVsAgheMqtKH9fh5mlPAt3cn1F8 So51Y+cgcUr9dCl3nwnrWEif2au6hBT69AuTECk0cZbNropH8VEwhK1tL2b+Mf+baRfS68fPU3h TzsbUWd+7vpe8p4TxUXZ/bc3TQo35n/c4W3j5WgZUNLnC/6w6 X-Received: by 2002:a2e:9b8e:0:b0:2d8:58ca:39ff with SMTP id z14-20020a2e9b8e000000b002d858ca39ffmr6757273lji.9.1712589211343; Mon, 08 Apr 2024 08:13:31 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHLhFeKUloD73IlTPGouL+pyJFXGlEI3cUESPCOuCP3kPx5Lx6wH2ASEqA34jqXHPB/sRarkQ== X-Received: by 2002:a2e:9b8e:0:b0:2d8:58ca:39ff with SMTP id z14-20020a2e9b8e000000b002d858ca39ffmr6757243lji.9.1712589210807; Mon, 08 Apr 2024 08:13:30 -0700 (PDT) Received: from ?IPV6:2003:cb:c718:1300:9860:66a2:fe4d:c379? (p200300cbc7181300986066a2fe4dc379.dip0.t-ipconnect.de. [2003:cb:c718:1300:9860:66a2:fe4d:c379]) by smtp.gmail.com with ESMTPSA id iv9-20020a05600c548900b004162ce49719sm14694586wmb.6.2024.04.08.08.13.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 08 Apr 2024 08:13:30 -0700 (PDT) Message-ID: <6ea2d90c-8a94-4361-af71-1a990bbe7096@redhat.com> Date: Mon, 8 Apr 2024 17:13:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 2/6] mm: swap: free_swap_and_cache_nr() as batched free_swap_and_cache() To: Ryan Roberts , Andrew Morton , Matthew Wilcox , Huang Ying , Gao Xiang , Yu Zhao , Yang Shi , Michal Hocko , Kefeng Wang , Barry Song <21cnbao@gmail.com>, Chris Li , Lance Yang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20240403114032.1162100-1-ryan.roberts@arm.com> <20240403114032.1162100-3-ryan.roberts@arm.com> <051052af-3b56-4290-98d3-fd5a1eb11ce1@redhat.com> <4110bb1d-65e5-4cf0-91ad-62749975829d@arm.com> <2cfa542a-ae38-4867-a64b-621e7778fdf7@arm.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: <2cfa542a-ae38-4867-a64b-621e7778fdf7@arm.com> 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-Rspamd-Queue-Id: 70B8F14001C X-Rspam-User: X-Stat-Signature: d1ci6a6rk6iaqgum6o6kcnhgm19fqz97 X-Rspamd-Server: rspam03 X-HE-Tag: 1712589215-547846 X-HE-Meta: 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 Qtwto2cD 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 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 08.04.24 15:27, Ryan Roberts wrote: > On 08/04/2024 13:47, Ryan Roberts wrote: >> On 08/04/2024 13:07, Ryan Roberts wrote: >>> [...] >>>> >>>> [...] >>>> >>>>> + >>>>> +/** >>>>> + * swap_pte_batch - detect a PTE batch for a set of contiguous swap entries >>>>> + * @start_ptep: Page table pointer for the first entry. >>>>> + * @max_nr: The maximum number of table entries to consider. >>>>> + * @entry: Swap entry recovered from the first table entry. >>>>> + * >>>>> + * Detect a batch of contiguous swap entries: consecutive (non-present) PTEs >>>>> + * containing swap entries all with consecutive offsets and targeting the same >>>>> + * swap type. >>>>> + * >>>> >>>> Likely you should document that any swp pte bits are ignored? () >>> >>> Now that I understand what swp pte bits are, I think the simplest thing is to >>> just make this function always consider the pte bits by using pte_same() as you >>> suggest below? I don't think there is ever a case for ignoring the swp pte bits? >>> And then I don't need to do anything special for uffd-wp either (below you >>> suggested not doing batching when the VMA has uffd enabled). >>> >>> Any concerns? >>> >>>> >>>>> + * max_nr must be at least one and must be limited by the caller so scanning >>>>> + * cannot exceed a single page table. >>>>> + * >>>>> + * Return: the number of table entries in the batch. >>>>> + */ >>>>> +static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, >>>>> +                 swp_entry_t entry) >>>>> +{ >>>>> +    const pte_t *end_ptep = start_ptep + max_nr; >>>>> +    unsigned long expected_offset = swp_offset(entry) + 1; >>>>> +    unsigned int expected_type = swp_type(entry); >>>>> +    pte_t *ptep = start_ptep + 1; >>>>> + >>>>> +    VM_WARN_ON(max_nr < 1); >>>>> +    VM_WARN_ON(non_swap_entry(entry)); >>>>> + >>>>> +    while (ptep < end_ptep) { >>>>> +        pte_t pte = ptep_get(ptep); >>>>> + >>>>> +        if (pte_none(pte) || pte_present(pte)) >>>>> +            break; >>>>> + >>>>> +        entry = pte_to_swp_entry(pte); >>>>> + >>>>> +        if (non_swap_entry(entry) || >>>>> +            swp_type(entry) != expected_type || >>>>> +            swp_offset(entry) != expected_offset) >>>>> +            break; >>>>> + >>>>> +        expected_offset++; >>>>> +        ptep++; >>>>> +    } >>>>> + >>>>> +    return ptep - start_ptep; >>>>> +} >>>> >>>> Looks very clean :) >>>> >>>> I was wondering whether we could similarly construct the expected swp PTE and >>>> only check pte_same. >>>> >>>> expected_pte = __swp_entry_to_pte(__swp_entry(expected_type, expected_offset)); >>> >>> So planning to do this. >> >> Of course this clears all the swp pte bits in expected_pte. So need to do something a bit more complex. >> >> If we can safely assume all offset bits are contiguous in every per-arch representation then we can do: > > Looks like at least csky and hexagon store the offset in discontiguous regions. > So it will have to be the second approach if we want to avoid anything > arch-specific. I'll assume that for now; we can always specialize > pte_next_swp_offset() per-arch in the future if needed. Sounds good. Just have a generic variant as you proposed, and add the per-arch one if really required later. -- Cheers, David / dhildenb