From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 2F12119C56C for ; Wed, 20 Nov 2024 10:48:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732099733; cv=none; b=fc1tIh4QAIN4xUImnKkWvBLOpxn2WJkbROCEQerqRdolxei9JRpdTJ05XizkXfPaElMfubD/3YySFzhGNzhPPuhnKMTAK8wO/Z7TvQBT1PUOPaIYYQUZ4yl31MtSy9ejfI8SrmCGIPcisHE7qYeeA0XAwlieEramULo6BhsLG4k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732099733; c=relaxed/simple; bh=XC8Mm92Ij6nVgJE1Djy3NtQ0fZS7oZmrFjKmK4b17TM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cbN70x1qFAzM8zMu35I64UInOvjBLHSdrcwlJ0zV1CJBpmTBwulW4uRjKFYj2vIEZwjicMAgZ/uzAHyTOlGOkICZgklyKxC/RXJolpoRcU4xnxeybL61AGb2Mqa6blPsDBSflOkGBD2F4jyKcsXpYt64DQVHbd7vYyFFC5qGvQM= 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=MsucGR9R; arc=none smtp.client-ip=170.10.133.124 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="MsucGR9R" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1732099730; 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=TYJiOMspK7IsPxdhCdCDQF9p6uoKVIA0MyWnICkfAEs=; b=MsucGR9RwDnFXUUOMPzbo07WFZqUJhBILV3CtDp8kIz7bQN+NKtbKO0UDWrmHGDgtjcQVq EnrdjEBYT6uG2QQZhfa9Y6BbvT3eUEL4NGqZaScHsilq1/Re3hHw4tmu0rB2Pu0mR4z1EK eWKoDsS57ZfLJ4omBHun/smhBcNe7uE= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-180-fz2NONdZP1qz7SV7OY_4iw-1; Wed, 20 Nov 2024 05:48:47 -0500 X-MC-Unique: fz2NONdZP1qz7SV7OY_4iw-1 X-Mimecast-MFC-AGG-ID: fz2NONdZP1qz7SV7OY_4iw Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-4316e2dde9eso39898145e9.2 for ; Wed, 20 Nov 2024 02:48:47 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732099726; x=1732704526; 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=TYJiOMspK7IsPxdhCdCDQF9p6uoKVIA0MyWnICkfAEs=; b=WvE+eLKbcWH++3kxpBec1CqIemwVbN9kNjtUP+54prfalbw2WYeQzs8d22SyK4fIiC q4q3blePLyPOwrJ4DtZ1rLYL6SK9R95oQfyl7xhhR4+gMkwOdkf/4jmmIa21PKSn6fcP r8DrtJNzFQSGONxLQEe10M94QXOPWFCPWqgC8W1xEoHENkuqRmDxj+zKpgYH1Qf89b/V TloLkilsTWoDtjfIA8uR4N7huFkvcT6WDwN6n2Smj8tlZUOMR5SZ1jnVp0SQCZaIOTzl 8QPS+666v8h35/LH5negDRC8R7rO8Krt3HY7O8wkudbED73wnEy6u2HG3YhsOWpOoG8V r0gQ== X-Forwarded-Encrypted: i=1; AJvYcCU0FSdTHCh0RQ2h88BzvsPfbVajZRQFVnOjBrIpiXEueNMNeaUhQLxx5x3oG2afK/iTHqeHP4LlZ3Nu@vger.kernel.org X-Gm-Message-State: AOJu0YxuU5bPfE+Fvo9MvIsaihAs4Z3UsMBeZ5DM5p/8e4TufKbJqc5a Q85Q6Y9UFKH3+N3euKf313KMS9YsNUTVGFemqEY2ooZOrLG1YMG2ohF+c+ShZUUfgrKCnJ4IevK oWQB9gtqdb8GGaCDZDPiNWmBG3xb/Ubcxo6/iWeYUHgN2phtWjKklGXQblow= X-Received: by 2002:a05:600c:4ed2:b0:431:52a3:d9d5 with SMTP id 5b1f17b1804b1-43348903e9dmr25118895e9.0.1732099726068; Wed, 20 Nov 2024 02:48:46 -0800 (PST) X-Google-Smtp-Source: AGHT+IH5ri0Ctyn0tsKk21xv1/ls13TeHxIMZx0VuvaIyqn9RF2BrSvePdGve47YAO822hbBk4iZ7Q== X-Received: by 2002:a05:600c:4ed2:b0:431:52a3:d9d5 with SMTP id 5b1f17b1804b1-43348903e9dmr25118425e9.0.1732099725605; Wed, 20 Nov 2024 02:48:45 -0800 (PST) Received: from ?IPV6:2003:cb:c705:4200:ce79:acf6:d832:60df? (p200300cbc7054200ce79acf6d83260df.dip0.t-ipconnect.de. [2003:cb:c705:4200:ce79:acf6:d832:60df]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-433b45fa728sm14606045e9.14.2024.11.20.02.48.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Nov 2024 02:48:44 -0800 (PST) Message-ID: <4b07a3eb-aad6-4436-9591-289c6504bb92@redhat.com> Date: Wed, 20 Nov 2024 11:48:42 +0100 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 07/11] fs/proc/vmcore: introduce PROC_VMCORE_DEVICE_RAM to detect device RAM ranges in 2nd kernel To: Baoquan He Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, kexec@lists.infradead.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Vivek Goyal , Dave Young , Thomas Huth , Cornelia Huck , Janosch Frank , Claudio Imbrenda , Eric Farman , Andrew Morton References: <20241025151134.1275575-1-david@redhat.com> <20241025151134.1275575-8-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 20.11.24 11:13, Baoquan He wrote: > On 10/25/24 at 05:11pm, David Hildenbrand wrote: >> s390 allocates+prepares the elfcore hdr in the dump (2nd) kernel, not in >> the crashed kernel. >> >> RAM provided by memory devices such as virtio-mem can only be detected >> using the device driver; when vmcore_init() is called, these device >> drivers are usually not loaded yet, or the devices did not get probed >> yet. Consequently, on s390 these RAM ranges will not be included in >> the crash dump, which makes the dump partially corrupt and is >> unfortunate. >> >> Instead of deferring the vmcore_init() call, to an (unclear?) later point, >> let's reuse the vmcore_cb infrastructure to obtain device RAM ranges as >> the device drivers probe the device and get access to this information. >> >> Then, we'll add these ranges to the vmcore, adding more PT_LOAD >> entries and updating the offsets+vmcore size. >> >> Use Kconfig tricks to include this code automatically only if (a) there is >> a device driver compiled that implements the callback >> (PROVIDE_PROC_VMCORE_DEVICE_RAM) and; (b) the architecture actually needs >> this information (NEED_PROC_VMCORE_DEVICE_RAM). >> >> The current target use case is s390, which only creates an elf64 >> elfcore, so focusing on elf64 is sufficient. >> >> Signed-off-by: David Hildenbrand >> --- >> fs/proc/Kconfig | 25 ++++++ >> fs/proc/vmcore.c | 156 +++++++++++++++++++++++++++++++++++++ >> include/linux/crash_dump.h | 9 +++ >> 3 files changed, 190 insertions(+) >> >> diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig >> index d80a1431ef7b..1e11de5f9380 100644 >> --- a/fs/proc/Kconfig >> +++ b/fs/proc/Kconfig >> @@ -61,6 +61,31 @@ config PROC_VMCORE_DEVICE_DUMP >> as ELF notes to /proc/vmcore. You can still disable device >> dump using the kernel command line option 'novmcoredd'. >> >> +config PROVIDE_PROC_VMCORE_DEVICE_RAM >> + def_bool n >> + >> +config NEED_PROC_VMCORE_DEVICE_RAM >> + def_bool n >> + >> +config PROC_VMCORE_DEVICE_RAM >> + def_bool y >> + depends on PROC_VMCORE >> + depends on NEED_PROC_VMCORE_DEVICE_RAM >> + depends on PROVIDE_PROC_VMCORE_DEVICE_RAM > > Kconfig item is always a thing I need learn to master. Yes, it's usually a struggle to get it right. It took me a couple of iterations to get to this point :) > When I checked > this part, I have to write them down to deliberate. I am wondering if > below 'simple version' works too and more understandable. Please help > point out what I have missed. > > ===========simple version====== > config PROC_VMCORE_DEVICE_RAM > def_bool y > depends on PROC_VMCORE && VIRTIO_MEM > depends on NEED_PROC_VMCORE_DEVICE_RAM > > config S390 > select NEED_PROC_VMCORE_DEVICE_RAM > ============ So the three changes you did are (a) Remove the config option but select/depend on them. (b) Remove the "depends on PROC_VMCORE" from PROC_VMCORE_DEVICE_RAM, and the "if PROC_VMCORE" from s390. (c) Remove the PROVIDE_PROC_VMCORE_DEVICE_RAM Regarding (a), that doesn't work. If you select a config option that doesn't exist, it is silently dropped. It's always treated as if it wouldn't be set. Regarding (b), I think that's an anti-pattern (having config options enabled that are completely ineffective) and I don't see a benefit dropping them. Regarding (c), it would mean that s390x unconditionally includes that code even if virtio-mem is not configured in. So while we could drop PROVIDE_PROC_VMCORE_DEVICE_RAM -- (c), it would that we end up including code in configurations that don't possibly need it. That's why I included that part. > > > ======= config items extracted from this patchset==== > config PROVIDE_PROC_VMCORE_DEVICE_RAM > def_bool n > > config NEED_PROC_VMCORE_DEVICE_RAM > def_bool n > > config PROC_VMCORE_DEVICE_RAM > def_bool y > depends on PROC_VMCORE > depends on NEED_PROC_VMCORE_DEVICE_RAM > depends on PROVIDE_PROC_VMCORE_DEVICE_RAM > > config VIRTIO_MEM > depends on X86_64 || ARM64 || RISCV > ~~~~~ I don't get why VIRTIO_MEM dones't depend on S390 if > s390 need PROC_VMCORE_DEVICE_RAM. This series depends on s390 support for virtio-mem, which just went upstream. See commit 38968bcdcc1d46f2fdcd3a72599d5193bf8baf84 Author: David Hildenbrand Date: Fri Oct 25 16:14:49 2024 +0200 virtio-mem: s390 support > ...... > select PROVIDE_PROC_VMCORE_DEVICE_RAM if PROC_VMCORE > > config S390 > select NEED_PROC_VMCORE_DEVICE_RAM if PROC_VMCORE > ================================================= > Thanks for having a look! -- Cheers, David / dhildenb