From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 39A1A24B234 for ; Fri, 10 Jan 2025 19:33:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736537583; cv=none; b=D/k+SY6ggwgiowDgewwYbdG22zY6rZTvZGp4DakrHEKQKboBHCuAz3OaDbCG3f6tN1ss2ZN8uZ2uzu1QW9ZNNiNtSNpq5FRCvp5/PW86zI3oet36RR+M0IJbHuy06p1gTMLiZvmxqVIjpRLhem18roFSdagvqIxh6r55wHcdyS8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736537583; c=relaxed/simple; bh=1a8pEB/FvtmSF9sWL6rji9jRBJikcarLGTrU/hyjRRA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FFzofvsqprSWLzg80it2RZ5eRW2lsOuNYVNlOUZEifP8uPJ+vfbDlB6GZ1lFVBBx7STe8xQ3ZXBwr6mfOxTEo4kIrZOtogZDLMxOJwi8ngD9FRqxxjDi8o8YYju5dijn9QEaNdXJJasAbl9f4CTf1+4RWm+jOlw6RjyzYCkyV8E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BLYhyBiM; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BLYhyBiM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736537580; 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=qDKb2TjmLs2z26Ys7026UZ48FqTIbV9FvAkbEz36Kx8=; b=BLYhyBiMm9FKk5XCP3ippx2fPhKsxWlxBMI8spHa+6nNVq766XtaFVG8ucDTQ6aOoqFohH iMEFayf15p0gPs/ca4n4f/7nxEAED/iSb6/an1sJ/4cgGJ+jffgYwmAmBUm9PNrpPV4sCO QHsGYIRHEokl7xzrLq6VoCTpMUN9GQc= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-629-gtIAQlYtNAG6xBAApNHxjw-1; Fri, 10 Jan 2025 14:32:56 -0500 X-MC-Unique: gtIAQlYtNAG6xBAApNHxjw-1 X-Mimecast-MFC-AGG-ID: gtIAQlYtNAG6xBAApNHxjw Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-43625ceae52so12993905e9.0 for ; Fri, 10 Jan 2025 11:32:56 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1736537576; x=1737142376; 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=qDKb2TjmLs2z26Ys7026UZ48FqTIbV9FvAkbEz36Kx8=; b=Ds+kP2mEAJ9Rfj4/A0EM+3rQkVQmic1H6cUK+CD0eZImuml+TQYN2gRW5wMB6AYsI1 CP12M9FS84wuIBUspNTxUToZ8goihHzEKPNOQpncrpTQXOPCgw1ovrEYOmfqF8hipFGw 9P15NlEyq2tD3bzAy71JzDkmIaXNkstmV2swveDSgHp02Mq2cOuUBTrtUpUXx+pvImmf SkbDhIne92gi3cL8j8dwoAX/J26Dfi+iltW1N48I8WHLG7T+tFtAg2FiGgX2VkwfXWKk ekwkhDJ4FOanVX6XaB8EwnSirTJXWUULzw/W48CE2MB7HWzP79Hwmv9kfxxCNeYBbO8k 0iJQ== X-Gm-Message-State: AOJu0YzY+JCpvzabbCZS11N/Y9dmaGu2FbJYLSdjs1T4EgtgEqRIDXsI j69FCe2TIRc1qukVQfshzSvoITBHU5oJK/eZbcIg4wBaYyw0fctLx2KTdx1KmfPDzZuxXWcHrzE qCx9c7RU/AnvA9lI4VoBFKZJTSHoac2Kj/WWbMzCoAGWi+i5y6tjrc2LFS21P6Q== X-Gm-Gg: ASbGnctLtx3+RoRjC6x1WFXiS7VUq3vpK7xe4T4oOY8JZnvPFRekwf0/IZM2Pbkent/ h8MsSVhU24SontHCBN7srYzDYs4pUnhm1VtSDpfpZJDPNOqmqMUe0pFohA/hxJvANy4SQb5iZIc 2EdxmPhzRQp6tJ82xUOTC/ya3CL7Z8Visw4ro79VdsgEMLy88mBkdGlibV9ZvKBtUJJcXX5o8iq oLCUVmbqJmbJZPqN5YREs3bwVprHhcCs3KPogbagEpv/Wat6wvew+7+c/tvb/EVeIdfjXvSh9De XHXL5YG2oPp8ngYlCjHeOHu48bbtX849V/JJV1Ti01McCN2dSybtKOoSkOGL11w51c5iHJMmr3U AdLMCGsSf X-Received: by 2002:a05:600c:470a:b0:42c:de2f:da27 with SMTP id 5b1f17b1804b1-436e2684ae0mr108853595e9.2.1736537575775; Fri, 10 Jan 2025 11:32:55 -0800 (PST) X-Google-Smtp-Source: AGHT+IHv7buGcmkzAVwbjWInhEvH9YkT454WApdDAoyUZMamfikExCmKyC7OmzJfv3RrB9TNSc+8Qw== X-Received: by 2002:a05:600c:470a:b0:42c:de2f:da27 with SMTP id 5b1f17b1804b1-436e2684ae0mr108853355e9.2.1736537575402; Fri, 10 Jan 2025 11:32:55 -0800 (PST) Received: from ?IPV6:2003:cb:c708:e100:4f41:ff29:a59f:8c7a? (p200300cbc708e1004f41ff29a59f8c7a.dip0.t-ipconnect.de. [2003:cb:c708:e100:4f41:ff29:a59f:8c7a]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a8e37e36asm5199428f8f.5.2025.01.10.11.32.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jan 2025 11:32:54 -0800 (PST) Message-ID: <542e2241-33ff-4ebd-9ee7-d95413d2ad1e@redhat.com> Date: Fri, 10 Jan 2025 20:32:52 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 6/6] mm/hugetlb: use folio->lru int demote_free_hugetlb_folios() To: Matthew Wilcox Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Muchun Song References: <20250110182149.746551-1-david@redhat.com> <20250110182149.746551-7-david@redhat.com> From: David Hildenbrand Content-Language: en-US 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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10.01.25 19:59, Matthew Wilcox wrote: > On Fri, Jan 10, 2025 at 07:21:49PM +0100, David Hildenbrand wrote: >> We are demoting hugetlb folios to smaller hugetlb folios; let's avoid >> messing with pages where avoidable. >> >> Signed-off-by: David Hildenbrand > > Good stuff. I have questions. > >> +++ b/mm/hugetlb.c >> @@ -3822,13 +3822,15 @@ static long demote_free_hugetlb_folios(struct hstate *src, struct hstate *dst, >> >> for (i = 0; i < pages_per_huge_page(src); i += pages_per_huge_page(dst)) { >> struct page *page = folio_page(folio, i); >> + struct folio *new_folio; > > I'm usually very against casting from page to folio, but I think it > might be the better option in this case ... > >> page->mapping = NULL; > > because then we could do new_folio->mapping = NULL. > > We're going to have to do serious changes to this function anyway to > convert from Ottawa to the New York interpretation, so the cast doesn't > give me the feeling of danger that it would elsewhere. Hm, that makes me wonder if we should do it even more similar like our other split function (__split_huge_page_tail)? diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 60617eecb99dd..23fe5654f632c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3821,14 +3821,18 @@ static long demote_free_hugetlb_folios(struct hstate *src, struct hstate *dst, pgalloc_tag_split(folio, huge_page_order(src), huge_page_order(dst)); for (i = 0; i < pages_per_huge_page(src); i += pages_per_huge_page(dst)) { struct page *page = folio_page(folio, i); + /* Careful: see __split_huge_page_tail() */ + struct folio *new_folio = (struct folio *)page; - page->mapping = NULL; clear_compound_head(page); prep_compound_page(page, dst->order); - init_new_hugetlb_folio(dst, page_folio(page)); - list_add(&page->lru, &dst_list); + new_folio->mapping = NULL; + init_new_hugetlb_folio(dst, new_folio); + list_add(&new_folio->lru, &dst_list); } } I was even wondering if we should be using nth_page() instead of folio_page() -- similar to __split_huge_page_tail. If we'd add sanity checking in current code to folio_page() to verify that i falls inside the folio, the current code would blow up as we modify the folio using prep_compound_page(). -- Cheers, David / dhildenb