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 ABDE11DFE31 for ; Tue, 8 Oct 2024 08:26:47 +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=1728376009; cv=none; b=q3+6DZJZm2jt9j7fnKcUZNxAxagn/k8JLmZXAI1ByNWHUrh1BTavXz62pKHfm1dgX77JBzbJ5hpTR1SThw1X73vPuukljpoMUHpJZY0u7yYAlVaHM3OfH4C8OG5uh39Qct+9rYM+9V8vI2vibXmV4/Oe3SwrWKK9x7RGUyI+WUU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728376009; c=relaxed/simple; bh=HHfYjD1YpA3Eq5+lIEuFEsasvtIG9UN3FlMl5jj6qeM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Jcgxf7Jkmk3GpSlc0tHKsqA8P+zFp7AkZvQGiU7hlgLuNIORJEJ9ZkzFvxOgfGeEUMdOM8uoK363Q3204GjHqfQF+kuL1prlUjm+6gKf0sJiL2V+UtCM1Q/vyvedxSYqBzDDvLB0MBuEjNlRNhJvT56xCYbgo6m73fmeTgecDQM= 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=Fwilkxa4; 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="Fwilkxa4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1728376006; 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=cOjJUPPhXg7FHSURpsWRXRS9eGsX5EzRwbqt9a/KOqs=; b=Fwilkxa4NhQRiyWm4g2q/x9UpXS50dkTuN3+kABFhIwHal81q0E6kmN3phd/1uKvV3VthE XKalkkVErheRUobrZ2Ue1UUybCpsM2eX7DLo7WggkoEUwBBv1rzUQghWwAgVXyzJrHRKDj zRLevhcGcjvjEfmGfHIAqV5N4YCUOFk= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-3-qBmTi-pQMGuzeOIk29bsmw-1; Tue, 08 Oct 2024 04:26:45 -0400 X-MC-Unique: qBmTi-pQMGuzeOIk29bsmw-1 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-42cb08ed3a6so29167535e9.0 for ; Tue, 08 Oct 2024 01:26:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728376004; x=1728980804; 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=cOjJUPPhXg7FHSURpsWRXRS9eGsX5EzRwbqt9a/KOqs=; b=ZC2rjzhI2i5MvzHb1WLt0STAqSecMSnoLwTkJfNRt22KsniTuY974cWZsWy6mjww9S bUgcndcoVDPVlI+tRJngIXAMDLmv0u0el6CrIFz8Sgdt3BG3W20c/iAA9hmmbE6wPhet nHYtayXp84uJRQsFI07tldwcoQxv1rG1zYPxw+idO2SkN8p2ZZbgyezMVYZy7vpaTCtt jR08cayZmL4V4HLbxX9R9S9V0birZDFScKNYnNLC0GTY6tokqVBK9O11H5Q53HP1HGOF zwd73CRTb68usmY2nsKOtc121J3kbb1J4eyVSqqGAlf90HnxuuFSi8FvwM4ggW6r54eF Vz0Q== X-Forwarded-Encrypted: i=1; AJvYcCVQuJvHa8owcosytM5rHQycFMuZoQgOCquErTlXp+ry2CM4+xvlBw8h57OUGvXYH44s4AQd8Zf9qqrPb/Y=@vger.kernel.org X-Gm-Message-State: AOJu0Yyg69+vbWi3tAyjrOj0kcVZTutSbb6irtXoMUk6bXbBu6D5Dusr bfM+6HdwihClzfEui7Jihk6xLYt3bWGPiDkkUYpYmvimT6lrS3UuaWYapCJs2IT9XF4/QF0I7co TtQtbSvM7XkA8/g5PIhNs6BDPtACv/LeWIa2B4P3zx58Q5qZftDvStFSJvgfZGg== X-Received: by 2002:a05:6000:4388:b0:374:be11:22d7 with SMTP id ffacd0b85a97d-37d291e4855mr1266566f8f.13.1728376004099; Tue, 08 Oct 2024 01:26:44 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEu3TPyBQ3L4hIAxIau3Zd48Xzi67YXUNgs2dOzN+sxzJaBIkGMRUy5UUj18X+Q8bjMaGLHMg== X-Received: by 2002:a05:6000:4388:b0:374:be11:22d7 with SMTP id ffacd0b85a97d-37d291e4855mr1266542f8f.13.1728376003692; Tue, 08 Oct 2024 01:26:43 -0700 (PDT) Received: from ?IPV6:2003:cb:c72f:c700:a76f:473d:d5cf:25a8? (p200300cbc72fc700a76f473dd5cf25a8.dip0.t-ipconnect.de. [2003:cb:c72f:c700:a76f:473d:d5cf:25a8]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37d1691a4cdsm7442141f8f.27.2024.10.08.01.26.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Oct 2024 01:26:43 -0700 (PDT) Message-ID: <9e4e3094-00a2-43bc-996f-af15c3168e3a@redhat.com> Date: Tue, 8 Oct 2024 10:26:42 +0200 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: [RFC PATCH] mm: avoid clearing user movable page twice with init_on_alloc=1 To: Zi Yan , linux-mm@kvack.org, Alexander Potapenko , Kees Cook Cc: Andrew Morton , "Matthew Wilcox (Oracle)" , Miaohe Lin , Kefeng Wang , John Hubbard , "Huang, Ying" , linux-kernel@vger.kernel.org References: <20241007182315.401167-1-ziy@nvidia.com> Content-Language: en-US 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: <20241007182315.401167-1-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 07.10.24 20:23, Zi Yan wrote: > Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and > init_on_free=1 boot options") forces allocated page to be cleared in > post_alloc_hook() when init_on_alloc=1. > > For non PMD folios, if arch does not define > vma_alloc_zeroed_movable_folio(), the default implementation again clears > the page return from the buddy allocator. So the page is cleared twice. > Fix it by passing __GFP_ZERO instead to avoid double page clearing. > At the moment, s390,arm64,x86,alpha,m68k are not impacted since they > define their own vma_alloc_zeroed_movable_folio(). > > For PMD folios, folio_zero_user() is called to clear the folio again. > Fix it by calling folio_zero_user() only if init_on_alloc is set. > All arch are impacted. > > Signed-off-by: Zi Yan > --- > include/linux/highmem.h | 14 ++------------ > mm/huge_memory.c | 4 +++- > 2 files changed, 5 insertions(+), 13 deletions(-) > > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index 930a591b9b61..4b15224842e1 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -220,18 +220,8 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr) > * Return: A folio containing one allocated and zeroed page or NULL if > * we are out of memory. > */ > -static inline > -struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, > - unsigned long vaddr) > -{ > - struct folio *folio; > - > - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr, false); > - if (folio) > - clear_user_highpage(&folio->page, vaddr); > - > - return folio; > -} > +#define vma_alloc_zeroed_movable_folio(vma, vaddr) \ > + vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr, false) > #endif > > static inline void clear_highpage(struct page *page) > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index a7b05f4c2a5e..ff746151896f 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1177,7 +1177,9 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, > goto release; > } > > - folio_zero_user(folio, vmf->address); > + if (!static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, > + &init_on_alloc)) > + folio_zero_user(folio, vmf->address); > /* > * The memory barrier inside __folio_mark_uptodate makes sure that > * folio_zero_user writes become visible before the set_pmd_at() I remember we discussed that in the past and that we do *not* want to sprinkle these CONFIG_INIT_ON_ALLOC_DEFAULT_ON checks all over the kernel. Ideally, we'd use GFP_ZERO and have the buddy just do that for us? There is the slight chance that we zero-out when we're not going to use the allocated folio, but ... that can happen either way even with the current code? -- Cheers, David / dhildenb