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[2003:cb:c749:6600:b73a:466c:e610:686]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4366127c639sm17416435e9.31.2024.12.19.05.05.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 19 Dec 2024 05:05:05 -0800 (PST) Message-ID: Date: Thu, 19 Dec 2024 14:05:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 4/5] mm/migrate: skip migrating folios under writeback with AS_WRITEBACK_INDETERMINATE mappings To: Joanne Koong , miklos@szeredi.hu, linux-fsdevel@vger.kernel.org Cc: shakeel.butt@linux.dev, jefflexu@linux.alibaba.com, josef@toxicpanda.com, bernd.schubert@fastmail.fm, linux-mm@kvack.org, kernel-team@meta.com, Matthew Wilcox , Zi Yan , Oscar Salvador , Michal Hocko References: <20241122232359.429647-1-joannelkoong@gmail.com> <20241122232359.429647-5-joannelkoong@gmail.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: <20241122232359.429647-5-joannelkoong@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: LvIEBhdyGDNBcef-lNK93uMTd-KZy6ODxXh0KY_AduM_1734613507 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: rspam10 X-Rspamd-Queue-Id: C2EB0120025 X-Stat-Signature: dxn41ud7f69xokf6gkim1mr4j4efyt95 X-Rspam-User: X-HE-Tag: 1734613463-956512 X-HE-Meta: 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 dLYjzxZj IhYFmWiVzFIPTeEBT/jmqYxYOw/phWmvwDs/O/D73viJWeqL7eco/P7+x0rjhrk0WmVjqjGg6n8gsn69SDjzRGd50YMfOpE/nTuTXGaLHE8Ox+xnXUhD96jXguXxsUaYbIyfppUbEIGK9rnHwcXy+tmULSXefEzgefJhyam97mdRmyf7ueiioR2ntUt1AsFFnGrmM5icoGC/auRImJL5PMugt7l6CR0q0vX2FweotCNg5p5l8Mv9DOrrIuQOaqgV29EwqJqC1gxA+xLEROcz1o7HRMvgp3h/Lu6EM4lugN7RABtL8CbZSOPc6dhAXVfkWg6S+kX0PtRTfRygalm9Ebjh5PrklNKQ1JpgMNlL+smbQsojJaBVGGrDM/DMvWr5NN6um1bjVkJSY3m5WBr+MojyJv+UyRJE/1j+EkRMTswIDZM6XyWDG9Co56Fe/B1hPOy791fqFDU31G2mS+YqUwiay4w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000141, 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 23.11.24 00:23, Joanne Koong wrote: > For migrations called in MIGRATE_SYNC mode, skip migrating the folio if > it is under writeback and has the AS_WRITEBACK_INDETERMINATE flag set on its > mapping. If the AS_WRITEBACK_INDETERMINATE flag is set on the mapping, the > writeback may take an indeterminate amount of time to complete, and > waits may get stuck. > > Signed-off-by: Joanne Koong > Reviewed-by: Shakeel Butt > --- > mm/migrate.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index df91248755e4..fe73284e5246 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1260,7 +1260,10 @@ static int migrate_folio_unmap(new_folio_t get_new_folio, > */ > switch (mode) { > case MIGRATE_SYNC: > - break; > + if (!src->mapping || > + !mapping_writeback_indeterminate(src->mapping)) > + break; > + fallthrough; > default: > rc = -EBUSY; > goto out; Ehm, doesn't this mean that any fuse user can essentially completely block CMA allocations, memory compaction, memory hotunplug, memory poisoning... ?! That sounds very bad. -- Cheers, David / dhildenb