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 01BE71714C6 for ; Wed, 4 Jun 2025 19:16:26 +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=1749064588; cv=none; b=I5IkDqN49UPe0mG9W+abX0U8oy/uUe6WwILr3kSjTHtbWZ0QBidOaXTycYpv2fdREu9Uot2BhGJX0OyUJQNbIbszA6vWH4VyfbdSSy6BMEgdKOAJ1kccMtXY5iYBrz59b76g9gegLBQb+aNBY9KzQlVXqwWlzTGiUOghXUxYeIY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749064588; c=relaxed/simple; bh=HuSPiJOYuRKWDSEZKBcJ+jpflJtdPO0ng3mXpOvfLR8=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=iV/Q2OAiYAwUBdPc2WrxhvpP3HGAnWu5pTnNz2UfUeXqPUtUJSzeZu2zNQdQbbqYgOWx8PbXQmHAgX5EjmYVs65UgxBEFwD1WgwDbZyJzjg+AV9WJCvdJLHwuMvzfCmYh8RfNEh2OlnRHf0hUvYa7UytvRkQbyFRjNHjkRiKqug= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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=OpbRUXBB; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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="OpbRUXBB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749064584; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to: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=rfu56wuubM001B/pgaMkp5G9PWTbiIJhIqTlXiTrxqU=; b=OpbRUXBBXMHIV7mSJ6xnuFCVkTUTT9l1rNVyQOt8zVz/MBdd3Ev4HmkzuhrncbmyFr/Oar bdxCrV970rfbDJi4E6qhYuGsCm4BRBz7q8jy8LDDPEvsMN18g81ZsXg4lDTbxPZIYkwjqt peuXd97n7XsHFrZKQ/6jFY5zn81+FHM= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-183-2wh-bb-UNT2pW0_t04S4DQ-1; Wed, 04 Jun 2025 15:16:20 -0400 X-MC-Unique: 2wh-bb-UNT2pW0_t04S4DQ-1 X-Mimecast-MFC-AGG-ID: 2wh-bb-UNT2pW0_t04S4DQ_1749064578 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3a4f85f31d9so185082f8f.1 for ; Wed, 04 Jun 2025 12:16:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749064578; x=1749669378; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=rfu56wuubM001B/pgaMkp5G9PWTbiIJhIqTlXiTrxqU=; b=rr+TR/bPDxl5qhbLkNtTGsN/fbJ911TYqdd0IenOQpMaxH/k6mc8Nn/ug1TQNrN9f0 wx2S4Z340hbY3H6Uzgn+RNzUYzNFGsVGLH/SOARdwLcBuqSwAcIjybqZutTorXxjQY67 wswat40XFcO002QGzXSY31xToa3/ejbgGRUONagLMGBbhGpETi/VToPJlJ1HAf8x1UN3 Fad3mGrK7SE5lb1veZaJF71t7ZNPROM7haiP1tJU+Bmjkj32SZQY+PDjZm0colzUjnxI +l3YZBGHQF6ZI4Ukuemc8UBqEEYE+OaiDUMuPMY/Zd1b7VFSaCI+ItCa0rBHkeAxH0Mg XsJQ== X-Forwarded-Encrypted: i=1; AJvYcCVZ7BywUnbhCdczK2hiyAylTBamiQ8xipkcyXzpBs2FQTSyeOpETsC0rpJOdOgqO+KN3+iGv4y5PHRJvA4=@vger.kernel.org X-Gm-Message-State: AOJu0YxY/TnTQgFTaJQhqF+uMnstV+MRWrLfhvddn+6aECx6ww2D3hVs F+qK8cDCQDcWxS4rnHbaQysvDbK8sXZO1ECzy8+EXfUryJmp1urZh6sepYixCaQDQtQISyT26Zh xP+w7Z6YQnv7rheGwXgvzVDV0bHVR3ASoGfXLCg7NE3f4ecqemShu8RKjma49FF9HEw== X-Gm-Gg: ASbGncuOotW263PbW76EBtbrIANyBVU0h4TfVgF/ux+9VeTsgRlVXMMg83ofewWbI81 uwf63M1mZ0EyeWYoIgYpy5DbSM1q8RlJgnKCdWxO1wv5d78TVBiB08Xtt5H1QgKwn6IBsTe7BCs Ey1AR7CBcJZxdIwzo95BQPXiNObNprgPWatUKUQS749WvmGjD2Nibs235fmK+UEoobkZcrZ4r9I R92hEjzucvhXwYXSxjAFX2GdT4IQaimGnxZxCUP8dTP8da07nVWRA45GeJHYyqgFgLm9Sd5YtD7 pmOxh61lLGTgO2vF5BgGUfrXuC7G6dUmKyyT1ljpDg== X-Received: by 2002:a5d:64ee:0:b0:391:3aaf:1d5f with SMTP id ffacd0b85a97d-3a51d97c83amr3564757f8f.52.1749064577911; Wed, 04 Jun 2025 12:16:17 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFsBr85DF/VWKVoy5wsZ3LFl+OisFHUCnMjMgzy50eu/xYDiBdrKcfoup3zde3lnswnlMQSxQ== X-Received: by 2002:a5d:64ee:0:b0:391:3aaf:1d5f with SMTP id ffacd0b85a97d-3a51d97c83amr3564743f8f.52.1749064577527; Wed, 04 Jun 2025 12:16:17 -0700 (PDT) Received: from [192.168.3.141] (p4fe0f831.dip0.t-ipconnect.de. [79.224.248.49]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a522322534sm2200127f8f.70.2025.06.04.12.16.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Jun 2025 12:16:17 -0700 (PDT) Message-ID: <23316621-0338-476f-b255-9ac4dff15d8b@redhat.com> Date: Wed, 4 Jun 2025 21:16:16 +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: [PATCH v1] mm/gup: remove (VM_)BUG_ONs To: "Liam R. Howlett" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , John Hubbard , Peter Xu References: <20250604140544.688711-1-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 04.06.25 21:12, Liam R. Howlett wrote: > * David Hildenbrand [250604 10:06]: >> Especially once we hit one of the assertions in >> sanity_check_pinned_pages(), observing follow-up assertions failing >> in other code can give good clues about what went wrong, so use >> VM_WARN_ON_ONCE instead. >> >> While at it, let's just convert all VM_BUG_ON to VM_WARN_ON_ONCE as >> well. Add one comment for the pfn_valid() check. >> >> We have to introduce VM_WARN_ON_ONCE_VMA() to make that fly. >> >> Drop the BUG_ON after mmap_read_lock_killable(), if that ever returns >> something > 0 we're in bigger trouble. Convert the other BUG_ON's into >> VM_WARN_ON_ONCE as well, they are in a similar domain "should never >> happen", but more reasonable to check for during early testing. >> >> Cc: Andrew Morton >> Cc: Lorenzo Stoakes >> Cc: "Liam R. Howlett" >> Cc: Vlastimil Babka >> Cc: Mike Rapoport >> Cc: Suren Baghdasaryan >> Cc: Michal Hocko >> Cc: Jason Gunthorpe >> Cc: John Hubbard >> Cc: Peter Xu >> Signed-off-by: David Hildenbrand > > seems okay, besides the one nit. > > Reviewed-by: Liam R. Howlett [...] >> >> ret = handle_mm_fault(vma, address, fault_flags, NULL); >> @@ -1760,10 +1760,7 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, >> } >> >> /* VM_FAULT_RETRY or VM_FAULT_COMPLETED cannot return errors */ >> - if (!*locked) { >> - BUG_ON(ret < 0); >> - BUG_ON(ret >= nr_pages); >> - } >> + VM_WARN_ON_ONCE(!*locked && (ret < 0 || ret >= nr_pages)); > > nit, we are losing accuracy on the value of ret here. I doubt it makes > much of a difference though. Yeah I doubt this will matter. Thanks! -- Cheers, David / dhildenb