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(p200300cbc70b7a009ccd0493d8e29ac8.dip0.t-ipconnect.de. [2003:cb:c70b:7a00:9ccd:493:d8e2:9ac8]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3825faf9dd2sm1906180f8f.26.2024.11.22.01.47.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Nov 2024 01:47:47 -0800 (PST) Message-ID: <3866cec8-9983-4adf-b96e-42fa728c84a8@redhat.com> Date: Fri, 22 Nov 2024 10:47:45 +0100 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 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: YPOfTJAWpcs2nZoTQtSsiZx6VDvx7HT-ncQlWcDhV3c_1732268869 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241122_014753_197846_95415F02 X-CRM114-Status: GOOD ( 17.24 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 22.11.24 08:31, Baoquan He wrote: > On 10/25/24 at 05:11pm, David Hildenbrand wrote: > ......snip... >> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c >> index 3e90416ee54e..c332a9a4920b 100644 >> --- a/fs/proc/vmcore.c >> +++ b/fs/proc/vmcore.c >> @@ -69,6 +69,8 @@ static LIST_HEAD(vmcore_cb_list); >> /* Whether the vmcore has been opened once. */ >> static bool vmcore_opened; >> >> +static void vmcore_process_device_ram(struct vmcore_cb *cb); >> + >> void register_vmcore_cb(struct vmcore_cb *cb) >> { >> INIT_LIST_HEAD(&cb->next); >> @@ -80,6 +82,8 @@ void register_vmcore_cb(struct vmcore_cb *cb) >> */ >> if (vmcore_opened) >> pr_warn_once("Unexpected vmcore callback registration\n"); >> + else if (cb->get_device_ram) >> + vmcore_process_device_ram(cb); > > Global variable 'vmcore_opened' is used to indicate if /proc/vmcore is > opened. With &vmcore_mutex, we don't need to worry about concurrent > opening and modification. However, if people just open /proc/vmcore and > close it after checking, then s390 will miss the vmcore dumping, is it > acceptable? See my reply to your other mail (patch #3). > >> mutex_unlock(&vmcore_mutex); >> } >> EXPORT_SYMBOL_GPL(register_vmcore_cb); >> @@ -1511,6 +1515,158 @@ int vmcore_add_device_dump(struct vmcoredd_data *data) > ...... >> + >> +static void vmcore_process_device_ram(struct vmcore_cb *cb) >> +{ >> + unsigned char *e_ident = (unsigned char *)elfcorebuf; >> + struct vmcore_mem_node *first, *m; >> + LIST_HEAD(list); >> + int count; >> + >> + if (cb->get_device_ram(cb, &list)) { >> + pr_err("Kdump: obtaining device ram ranges failed\n"); >> + return; >> + } >> + count = list_count_nodes(&list); >> + if (!count) >> + return; >> + >> + /* We only support Elf64 dumps for now. */ >> + if (WARN_ON_ONCE(e_ident[EI_CLASS] != ELFCLASS64)) { >> + pr_err("Kdump: device ram ranges only support Elf64\n"); >> + goto out_free; >> + } > > Only supporting Elf64 dumps seems to be a basic checking, do we need > to put it at the beginning of function? Otherwise, we spend efforts to > call cb->get_device_ram(), then fail. The idea was that if there is nothing to add, then the elf class doesn't matter. But yes, I can move this further up. Thanks! -- Cheers, David / dhildenb