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[2003:cb:c707:5c00:e650:bcd7:e2a0:54fe]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4282bb98109sm48914275e9.39.2024.08.01.02.32.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 01 Aug 2024 02:32:45 -0700 (PDT) Message-ID: <48b720d6-3cd6-4c0b-a887-385de9f39bd2@redhat.com> Date: Thu, 1 Aug 2024 11:32:43 +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 v2] mm/migrate: fix deadlock in migrate_pages_batch() on large folios To: Gao Xiang , Andrew Morton , Huang Ying , linux-mm@kvack.org, Matthew Wilcox , linux-kernel@vger.kernel.org References: <20240729021306.398286-1-hsiangkao@linux.alibaba.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: <20240729021306.398286-1-hsiangkao@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29.07.24 04:13, Gao Xiang wrote: > Currently, migrate_pages_batch() can lock multiple locked folios > with an arbitrary order. Although folio_trylock() is used to avoid > deadlock as commit 2ef7dbb26990 ("migrate_pages: try migrate in batch > asynchronously firstly") mentioned, it seems try_split_folio() is > still missing. > > It was found by compaction stress test when I explicitly enable EROFS > compressed files to use large folios, which case I cannot reproduce with > the same workload if large folio support is off (current mainline). > Typically, filesystem reads (with locked file-backed folios) could use > another bdev/meta inode to load some other I/Os (e.g. inode extent > metadata or caching compressed data), so the locking order will be: > > file-backed folios (A) > bdev/meta folios (B) > > The following calltrace shows the deadlock: > Thread 1 takes (B) lock and tries to take folio (A) lock > Thread 2 takes (A) lock and tries to take folio (B) lock > > [Thread 1] > INFO: task stress:1824 blocked for more than 30 seconds. > Tainted: G OE 6.10.0-rc7+ #6 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:stress state:D stack:0 pid:1824 tgid:1824 ppid:1822 flags:0x0000000c > Call trace: > __switch_to+0xec/0x138 > __schedule+0x43c/0xcb0 > schedule+0x54/0x198 > io_schedule+0x44/0x70 > folio_wait_bit_common+0x184/0x3f8 > <-- folio mapping ffff00036d69cb18 index 996 (**) > __folio_lock+0x24/0x38 > migrate_pages_batch+0x77c/0xea0 // try_split_folio (mm/migrate.c:1486:2) > // migrate_pages_batch (mm/migrate.c:1734:16) > <--- LIST_HEAD(unmap_folios) has > .. > folio mapping 0xffff0000d184f1d8 index 1711; (*) > folio mapping 0xffff0000d184f1d8 index 1712; > .. > migrate_pages+0xb28/0xe90 > compact_zone+0xa08/0x10f0 > compact_node+0x9c/0x180 > sysctl_compaction_handler+0x8c/0x118 > proc_sys_call_handler+0x1a8/0x280 > proc_sys_write+0x1c/0x30 > vfs_write+0x240/0x380 > ksys_write+0x78/0x118 > __arm64_sys_write+0x24/0x38 > invoke_syscall+0x78/0x108 > el0_svc_common.constprop.0+0x48/0xf0 > do_el0_svc+0x24/0x38 > el0_svc+0x3c/0x148 > el0t_64_sync_handler+0x100/0x130 > el0t_64_sync+0x190/0x198 > > [Thread 2] > INFO: task stress:1825 blocked for more than 30 seconds. > Tainted: G OE 6.10.0-rc7+ #6 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:stress state:D stack:0 pid:1825 tgid:1825 ppid:1822 flags:0x0000000c > Call trace: > __switch_to+0xec/0x138 > __schedule+0x43c/0xcb0 > schedule+0x54/0x198 > io_schedule+0x44/0x70 > folio_wait_bit_common+0x184/0x3f8 > <-- folio = 0xfffffdffc6b503c0 (mapping == 0xffff0000d184f1d8 index == 1711) (*) > __folio_lock+0x24/0x38 > z_erofs_runqueue+0x384/0x9c0 [erofs] > z_erofs_readahead+0x21c/0x350 [erofs] <-- folio mapping 0xffff00036d69cb18 range from [992, 1024] (**) > read_pages+0x74/0x328 > page_cache_ra_order+0x26c/0x348 > ondemand_readahead+0x1c0/0x3a0 > page_cache_sync_ra+0x9c/0xc0 > filemap_get_pages+0xc4/0x708 > filemap_read+0x104/0x3a8 > generic_file_read_iter+0x4c/0x150 > vfs_read+0x27c/0x330 > ksys_pread64+0x84/0xd0 > __arm64_sys_pread64+0x28/0x40 > invoke_syscall+0x78/0x108 > el0_svc_common.constprop.0+0x48/0xf0 > do_el0_svc+0x24/0x38 > el0_svc+0x3c/0x148 > el0t_64_sync_handler+0x100/0x130 > el0t_64_sync+0x190/0x198 > > Fixes: 5dfab109d519 ("migrate_pages: batch _unmap and _move") > Cc: "Huang, Ying" > Cc: Matthew Wilcox > Signed-off-by: Gao Xiang > --- Acked-by: David Hildenbrand -- Cheers, David / dhildenb