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 BEB73C5AD49 for ; Fri, 6 Jun 2025 08:23:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 55F476B008A; Fri, 6 Jun 2025 04:23:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 537B86B008C; Fri, 6 Jun 2025 04:23:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 425C86B0092; Fri, 6 Jun 2025 04:23:22 -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 247086B008A for ; Fri, 6 Jun 2025 04:23:22 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 3593E1203C9 for ; Fri, 6 Jun 2025 08:23:21 +0000 (UTC) X-FDA: 83524286202.16.EE2A969 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf10.hostedemail.com (Postfix) with ESMTP id BB034C000C for ; Fri, 6 Jun 2025 08:23:18 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=gbqA3SKg; spf=pass (imf10.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1749198198; 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=6ajWNDkIGe/RPonsgk1x1omUJ/bvYDkNNzEILiZ4Kgg=; b=4OKJbqdd49u68AP6zDGq6CYgZhFIfJoQVe6OS5G6TaTFanaNrtuG3VM23YvaL1HPjLAvNc uDNSgDpQjALzoW12PdgCwZv99ECDiyqsiDxPvYntv0gvIzCYH4ETEwdw/KusAdoHeXfzR+ 2Bmyoot5ETJ8BUPt+Qt95VCrtQyaClM= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=gbqA3SKg; spf=pass (imf10.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1749198198; a=rsa-sha256; cv=none; b=FUlLd9iWYWGZmnpbo/tpMykXFQSCam6udQF5PfgM2Ml3H0r4qbeB+HzZYlfg4qzArgl1tP I59wfz6duhLdSvL+xEMOxurLbwZV78MvJi+AxJjuaWkaLh9krqPOybCwDBAjIfSKNJ8hFe BatT9hbWWi855d+KSCB6FWNpxjI2gtc= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749198198; 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=6ajWNDkIGe/RPonsgk1x1omUJ/bvYDkNNzEILiZ4Kgg=; b=gbqA3SKgTzAtHmf39rSJCaDt/pKoEViLatkmpaK0ZkoJHFIMipAzbdVmhGGRcP1KL3Z6pY euTot52vUyu7WOu8Z2UA3HuoC0MdZG76dTwPqa6SIhTMBqNfLsFHrge1LkoCyroET5gT/9 pOlmQ4blAL/BkqwgZYnsgF5nqq3xuLo= 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-198-S3zSRLLoM8WfC1P4WNcwJw-1; Fri, 06 Jun 2025 04:23:17 -0400 X-MC-Unique: S3zSRLLoM8WfC1P4WNcwJw-1 X-Mimecast-MFC-AGG-ID: S3zSRLLoM8WfC1P4WNcwJw_1749198196 Received: by mail-wr1-f72.google.com with SMTP id ffacd0b85a97d-3a4f3796779so1334029f8f.1 for ; Fri, 06 Jun 2025 01:23:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749198195; x=1749802995; 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=6ajWNDkIGe/RPonsgk1x1omUJ/bvYDkNNzEILiZ4Kgg=; b=cBSJceXQp4oWiS60gPfQDqXCzoCDogL89SWB8O3GDS8CKOuxBRJuRdP0pTaqIkqKGW qBWrw7B39AYjOb1vE4S8eiW7gf9wnTPG087n3ban4ukXjQK1lqUtSKApQ3k2JR9oNvdh k3BSPWCjO8F8MqYSFiK8bV+yQ8f0EAFPQgPBFyWm2yY6yoNBcXuDCdc78pW7qdpAK+Hx iyCE8YVBmU+hCBJRsErQPFurmIK6l3F/qzUkHfoZ6JZ/Q4xp3o9huzJyJTYn2lttRXx6 CvYVI64yAW6XZoP3Vr80WdHfscBqcnwNN22nnLrmYr7FxBBn69KbsBaoI7udP28q/Jiw ol3Q== X-Forwarded-Encrypted: i=1; AJvYcCWfi9+sxC+8UNmQQ528RgcoSLpQRZr4WUXd1SIZC/QIC4d/bsiOtWJGXHLY2/ODkApr/mepi4oV3w==@kvack.org X-Gm-Message-State: AOJu0Yxf8BjhwAliNCrgAytbJ1CBpbSLU9ieIyXR8txfxegPf2MVozlu ucEeRZuyXOeaGjlXjCZpmEncYou0XESyLRJRUpILPusZsiw+p+vf46Bm7aTwHyGrgrSOCHKDOwn 4pwqLD+Fc10xEnMe2Un3tAANoaecJLtM3+LiKd3rgfRnJ3lsxToGo X-Gm-Gg: ASbGncuFWwAU+bGqpjkJDuuk4riI0KRCYALqY7Eg9ThSf2eBN4C1C0V8uLZY7xjcIH4 /uR92yeQ+m9yFzVqWh+1Ch8Q12jRQwNlCt4NA2/BY1C47TmoDbMV9UBvVLYeMcYrmYSSLAVvtgF 5xvPkPPOJrLeyZWyZwRZKvHbf1NLr/tAdRhIVKk0nGmRzmKsBwnsX1g6hfU2QzHzRLZzSiNUQ7V 1We4u0pxTEVz5a3z2CE75enliFAD9IxUM/RyIYTErLVJPpXy8ZtMqnmMs+nwBL2Q2wCly8kW6Wv QDaZHN8rNtnSIco+7YxFYzedyknqTalKu4758yfm2NsDwxxMJfvf833C1/XJ7bW/PlUxojaxDY/ +K3tmP3vLQpd4JGS/64Lif0+Yvehjb4s= X-Received: by 2002:a05:6000:2585:b0:39f:175b:a68d with SMTP id ffacd0b85a97d-3a53188da55mr1982155f8f.11.1749198195597; Fri, 06 Jun 2025 01:23:15 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGgzY8Eq+Aj8NnhMsDe8lTl3DU6IfHWx3dR5ziy4gZ5Wc1+1k9JZmrf+nIDql3bue6WAHNteQ== X-Received: by 2002:a05:6000:2585:b0:39f:175b:a68d with SMTP id ffacd0b85a97d-3a53188da55mr1982112f8f.11.1749198195141; Fri, 06 Jun 2025 01:23:15 -0700 (PDT) Received: from ?IPV6:2003:d8:2f19:9c00:568:7df7:e1:293d? (p200300d82f199c0005687df700e1293d.dip0.t-ipconnect.de. [2003:d8:2f19:9c00:568:7df7:e1:293d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a5323ab1a2sm1165901f8f.28.2025.06.06.01.23.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Jun 2025 01:23:14 -0700 (PDT) Message-ID: Date: Fri, 6 Jun 2025 10:23:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/2] mm/huge_memory: don't mark refcounted pages special in vmf_insert_folio_pmd() To: Oscar Salvador Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Andrew Morton , Alistair Popple , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Dan Williams References: <20250603211634.2925015-1-david@redhat.com> <20250603211634.2925015-2-david@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-MFC-PROC-ID: GrHpWfCPVnNd5pruAjfDL31RPoe1tbQ7bYGUH7bGn10_1749198196 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: xwm7oku9488njqg5fcpz43j4xuwfkkba X-Rspamd-Queue-Id: BB034C000C X-Rspamd-Server: rspam11 X-HE-Tag: 1749198198-322619 X-HE-Meta: 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 qcdHzOi7 jWrlvyajk3A01cCXnZkyst7favFKB9BSGIRty3I74KqKDViuEkbKGYbfxN2gbQvm1DU0hISwvekYp+A9yR3/jxeuuM0EjQRDBYvVgvUab8yfDsdB0PhV0DkKA0gd0Jnf3cYSEGU/DoiNgV4Mar3pwxdkTEPcc3SZ8LLVTyGhh974BbdNX3oGLXfGdZLAd6g7SDCT6/1+jwxfa9uSljao4Sn4PdJ2oL3KtEbUFBApYABbNX5mSjf9eoYnLVjHVfgTheKzT93wGHXW+CDPdMhf8io/0VhonvVtxAToTRDhYGoKdieFSqIhDivqF6Lrmo10vG5sJz+vof+sp8VtmiPjFH58RP8oAskE+uEl++/R9Ixr2CTRlN8Q+aIG/rD6r8R9zPGpO78vFNQIucM2TwsXpX7WdbFbV/gp0zlbpIqONkJHIaW1qaXf+ygbmRG2rWgYTPX7LKaFQKsi/2WeEqCdRKADyub+due82FGeX 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 06.06.25 10:20, Oscar Salvador wrote: > On Tue, Jun 03, 2025 at 11:16:33PM +0200, David Hildenbrand wrote: >> Marking PMDs that map a "normal" refcounted folios as special is >> against our rules documented for vm_normal_page(). >> >> Fortunately, there are not that many pmd_special() check that can be >> mislead, and most vm_normal_page_pmd()/vm_normal_folio_pmd() users that >> would get this wrong right now are rather harmless: e.g., none so far >> bases decisions whether to grab a folio reference on that decision. >> >> Well, and GUP-fast will fallback to GUP-slow. All in all, so far no big >> implications as it seems. >> >> Getting this right will get more important as we use >> folio_normal_page_pmd() in more places. >> >> Fix it by just inlining the relevant code, making the whole >> pmd_none() handling cleaner. We can now use folio_mk_pmd(). >> >> While at it, make sure that a pmd that is not-none is actually present >> before comparing PFNs. >> >> Fixes: 6c88f72691f8 ("mm/huge_memory: add vmf_insert_folio_pmd()") >> Signed-off-by: David Hildenbrand > > Hi David, > >> --- >> mm/huge_memory.c | 39 ++++++++++++++++++++++++++++++++------- >> 1 file changed, 32 insertions(+), 7 deletions(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index d3e66136e41a3..f9e23dfea76f8 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -1474,9 +1474,10 @@ vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio, >> struct vm_area_struct *vma = vmf->vma; >> unsigned long addr = vmf->address & PMD_MASK; >> struct mm_struct *mm = vma->vm_mm; >> + pmd_t *pmd = vmf->pmd; >> spinlock_t *ptl; >> pgtable_t pgtable = NULL; >> - int error; >> + pmd_t entry; >> >> if (addr < vma->vm_start || addr >= vma->vm_end) >> return VM_FAULT_SIGBUS; >> @@ -1490,17 +1491,41 @@ vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio, >> return VM_FAULT_OOM; >> } >> >> - ptl = pmd_lock(mm, vmf->pmd); >> - if (pmd_none(*vmf->pmd)) { >> + ptl = pmd_lock(mm, pmd); >> + if (pmd_none(*pmd)) { >> folio_get(folio); >> folio_add_file_rmap_pmd(folio, &folio->page, vma); >> add_mm_counter(mm, mm_counter_file(folio), HPAGE_PMD_NR); >> + >> + entry = folio_mk_pmd(folio, vma->vm_page_prot); >> + if (write) { >> + entry = pmd_mkyoung(pmd_mkdirty(entry)); >> + entry = maybe_pmd_mkwrite(entry, vma); >> + } >> + set_pmd_at(mm, addr, pmd, entry); >> + update_mmu_cache_pmd(vma, addr, pmd); >> + >> + if (pgtable) { >> + pgtable_trans_huge_deposit(mm, pmd, pgtable); >> + mm_inc_nr_ptes(mm); >> + pgtable = NULL; >> + } >> + } else if (pmd_present(*pmd) && write) { >> + /* >> + * We only allow for upgrading write permissions if the >> + * same folio is already mapped. >> + */ >> + if (pmd_pfn(*pmd) == folio_pfn(folio)) { >> + entry = pmd_mkyoung(*pmd); >> + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); >> + if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) >> + update_mmu_cache_pmd(vma, addr, pmd); >> + } else { >> + WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); >> + } > > So, this is pretty much insert_pfn_pmd without pmd_mkdevmap/pmd_mkspecial(). > I guess vmf_inser_folio_pmd() doesn't have to be concerned with devmaps > either, right? > > Looks good to me, just a nit: would it not be better to pass a boolean > to insert_pfn_pmd() that lets it know whether it "can" create a > devmap/special entries? See my reply to Dan. Yet another boolean, yuck. Passing the folio and the pfn, yuck. (I have a strong opinion here ;) ) -- Cheers, David / dhildenb