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[79.242.56.157]) by smtp.gmail.com with ESMTPSA id j12-20020a05600c190c00b004189a5ada3asm728027wmq.19.2024.04.16.00.05.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 16 Apr 2024 00:05:15 -0700 (PDT) Message-ID: Date: Tue, 16 Apr 2024 09:05:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/2] s390/mm: re-enable the shared zeropage for !PV and !skeys KVM guests To: Alexander Gordeev , Christian Borntraeger Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Andrew Morton , Peter Xu , Sven Schnelle , Gerald Schaefer , Andrea Arcangeli , kvm@vger.kernel.org, linux-s390@vger.kernel.org References: <20240411161441.910170-1-david@redhat.com> <20240411161441.910170-3-david@redhat.com> <8533cb18-42ff-42bc-b9e5-b0537aa51b21@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: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AFC861A0011 X-Stat-Signature: png1u78tjkpzunr34fifzqcptaerdgxx X-HE-Tag: 1713251120-780721 X-HE-Meta: U2FsdGVkX18HeXuDAtfkc8Tr4TipGushkK9SnJAdhFvxXtwMckpfFJaQ9T1bg2yzP51qlREYUkc+crsJSIAGBv19XAH80PcwOjmXLZwZtX4VmyWwWOKXJXuOcVE6hIER2ncGQ/za/c+jNwtHQPjCGcPmJ+vRIs2t3zuta/HA5LwEycqQ++6MqV84UCqMQgyWQfsJYTF45dIpcYQc0D7Jkho3nX2vPU0jl+9r8ZQdTq3TvEICo9zy+S7K+6IKKoFV8Z1n+IuUS1h67HHqIIfJFysgRCm0EGrdXU2ZztDIyu6jWo8v+nfz6UQ5Bmdb0XwUMWRtSbBHOz2fX2D9vOm5vsYMG5MEZqZK+25UdwPiq8D35ifL7FWEFwW4Oo5p8Q5+prm3Eop4U8WEfHSB7xNSnQ1amkAWXK7hW6FjIz2HyGOjf30PkXbN22M/6EOymnNWKJtgyCQAsXXzyLVCxNoSY8lQ0c3XmEoYpPH9jbXu76DcMP0AXvRZe3IBeqt9kUL57npUoJ+HCzZb4d6WxrSdocm4DSMLgYtg2ctk5tRRL98OnrejMBb5k07Pb0PvLU6T7il5UmSuPkZfm6pQw6PGWxxuWU+zeYM/veO0Aibisrfpg+Y6TlnR/D+uVcz252cjO8ywdAKAmXXpBKWr+idk2Asr360G/F3mLgx/0mg6rbSKp6fxsO0O5NltFUVD9pvcHfcEy2MhYLE6lkjdpn73tj4o7LLi/4QTeqgNVjfnxI0FlnH4QIAgdKUpvSpbe5zc+U22BuhLMjpivaLXjaroH6Hl22X4XCU2FJ2yOVG/DjkXYxEjJ0gF5vHtiA09Dmmx4q4UKOLqjAPvcxFXiGaun246R9UfHfZJb0s+w9GlDEunmnmFay+JqA9hsGtjY6aM/vgt1IrWR5cVQ1Qt2cy1u2qLUTtoM7wrV5dyphrR9Mh5E4MfA/Cx/ZRc68ifQ5MBsIXlH+pQuYqi+SdZ/5y RPxDRCdZ kughR3RZ2Az9DTGqNWtkK/Srosdmnvln5FbMzDNnvJKolvRxcQBAKvCPxAvG7LIpgXDBdcLEvwyoippmFnkOiuSYP5/JOEmtrsafJ6ZamAED/uru0wuRpyjD8L+Z0KexO6cuBMBbKGecwO9b9/MCRjmPgYbi71uFGsjtaFi8WHoCxAbEayLAr+iBOXQFBHMhZE30cqI1TDobNszVHFH27N0DAw/palOcQBlKOT35YBHAbC02+HkrLxUlO01j4h3Ot3ipccLH46gP0esmLGTxNiIawcj9QBkWO6Z/Bmk9SaFSsDo95eRPu4ICVc6WeyiQJraWjsVSdGTZtELfJ8UdcTgChdHwaCjSvoyRZzVvwz4cjC488sPf4Ebk3+pkMFzKZ6HqdvEl7uh5O5F6/dBwc32o9zvpbGResHI5kKFoXQekxN2Bl5BtgMF+x5A3yaxTELMbpcby7YCwCC8u6KoTWZz+Z3oGVrIuhCWPFNkZe2AFKSR0= 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 16.04.24 08:37, Alexander Gordeev wrote: > On Mon, Apr 15, 2024 at 09:14:03PM +0200, David Hildenbrand wrote: >>>> +retry: >>>> + rc = walk_page_range_vma(vma, addr, vma->vm_end, >>>> + &find_zeropage_ops, &addr); >>>> + if (rc <= 0) >>>> + continue; >>> >>> So in case an error is returned for the last vma, __s390_unshare_zeropage() >>> finishes with that error. By contrast, the error for a non-last vma would >>> be ignored? >> >> Right, it looks a bit off. walk_page_range_vma() shouldn't fail >> unless find_zeropage_pte_entry() would fail -- which would also be >> very unexpected. >> >> To handle it cleanly in case we would ever get a weird zeropage where we >> don't expect it, we should probably just exit early. >> >> Something like the following (not compiled, addressing the comment below): > >> @@ -2618,7 +2618,8 @@ static int __s390_unshare_zeropages(struct mm_struct *mm) >> struct vm_area_struct *vma; >> VMA_ITERATOR(vmi, mm, 0); >> unsigned long addr; >> - int rc; >> + vm_fault_t rc; >> + int zero_page; > > I would use "fault" for mm faults (just like everywhere else handle_mm_fault() is > called) and leave rc as is: > > vm_fault_t fault; > int rc; Sure, let me know once discussion here stopped whether you want a v4 or can fix that up. -- Cheers, David / dhildenb