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[91.12.110.22]) by smtp.gmail.com with ESMTPSA id e16-20020adfe390000000b0032dab20e773sm13545222wrm.69.2023.10.26.00.00.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 Oct 2023 00:00:56 -0700 (PDT) Message-ID: <2a7b5e72-604a-48e1-9c0e-3b9ad15e7f78@redhat.com> Date: Thu, 26 Oct 2023 09:00:55 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/sparsemem: fix race in accessing memory_section->usage To: Andrew Morton , Charan Teja Kalla Cc: Pavan Kondeti , osalvador@suse.de, dan.j.williams@intel.com, vbabka@suse.cz, mgorman@techsingularity.net, aneesh.kumar@linux.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1697202267-23600-1-git-send-email-quic_charante@quicinc.com> <20231025143541.e7cf114239b84105711a5f70@linux-foundation.org> 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: <20231025143541.e7cf114239b84105711a5f70@linux-foundation.org> 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-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: CF24E1C0008 X-Stat-Signature: 7bcowmn7uepwxa486unefdqgnngnuoj9 X-Rspam-User: X-HE-Tag: 1698303661-310457 X-HE-Meta: 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 s9GLAi4G 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 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 25.10.23 23:35, Andrew Morton wrote: > On Tue, 17 Oct 2023 19:40:15 +0530 Charan Teja Kalla wrote: > >>>> * was allocated during boot. >>>> */ >>>> if (!PageReserved(virt_to_page(ms->usage))) { >>>> + synchronize_rcu(); >>>> kfree(ms->usage); >>>> ms->usage = NULL; >>>> } >>> If we add NULL checks around ms->usage, this becomes >>> >>> tmp = rcu_replace_pointer(ms->usage, NULL, hotplug_locked()); >>> syncrhonize_rcu(); >>> kfree(tmp); >> Per David input, I am working on using kfree_rcu(). > > How's it coming along? > > Given that we're at 6.6-rc7 and given that this issue is causing > daily crashes in your device farm, I'm thinking that we use the current > version of your patch for 6.6 and for -stable. We can look at the > kfree_rcu() optimization for later kernel releases? Any particular reason we have to rush this in? It's been seen by one company in a testing farm; there were no other reports, especially not from production systems. ... and the issue seems to be quite old. -- Cheers, David / dhildenb