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[2003:d8:2f4f:2b00:69b5:3684:56c:6dd5]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-422874de5d5sm89244655e9.33.2024.06.14.01.51.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Jun 2024 01:51:11 -0700 (PDT) Message-ID: Date: Fri, 14 Jun 2024 10:51:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 3/3] mm: remove folio_test_anon(folio)==false path in __folio_add_anon_rmap() To: Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, linux-mm@kvack.org, chrisl@kernel.org, linux-kernel@vger.kernel.org, mhocko@suse.com, ryan.roberts@arm.com, baolin.wang@linux.alibaba.com, yosryahmed@google.com, shy828301@gmail.com, surenb@google.com, v-songbaohua@oppo.com, willy@infradead.org, ying.huang@intel.com, yuzhao@google.com References: <20240613000721.23093-1-21cnbao@gmail.com> <20240613000721.23093-4-21cnbao@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: 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: 8bit X-Stat-Signature: t758tuts96zhq9ig8inqme19qstqwiyh X-Rspamd-Queue-Id: 997F8100015 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1718355077-489964 X-HE-Meta: U2FsdGVkX1++h6W64Ih62x6G4e4NQapyXLLZWSSIZNvcFbhczfLhP8Rgzf8jCS904eGe6WeYcX4mUEp1XLbFZFyqNSZPmDPpZDkp6T/wYUlLABkDMOn/GdTp+TQQiC8wCwglnqjYuIHbwIuUkhu9tOnbd9qwlMMRW1ZlzpXyLRQ+0of7waXmkr5bmowZheKMcfj76r2XMG35yfUxpE9DgsdqxENcforTiI+bxwtVIOouBPh5cuVmKbMjm2ROKIDxf8QMwgt80cdmq/Ye3pjCraUYbAY73Bc6Fb0BzbpUgyPYmO1WbOA1+kMdXj3HhgV/xVdRXghX24tQNJXUG7IupcWts/H9H2DnForII/3dTl/FcJaLcskwfVSxmZhO2Am12OT/PuhNeCLpVJHkadu6iCAPvLP4k0yj5/7/iVBbJ/nn87RdeGHHwvMZ+tyQfIIRtJpl22+c7pyCyiJUTi7eiJ94dXEpaGUGKjAoIhkYYfkSBujNCXM8AOi3CofKcIwf2mjmo+2P48l5DtQT4U/ShDva0e9SAjyWNaOrMaf90R5MvomTgfAtIGD2Q3mVmdi5PRtCQVvC8H/m1UgLYfm7Aw9odH4S/wnwVTMZ2+MuCk47ytgJO1xct86XmtKQRu2G/od6IqWr8jR7Hcsjk2ZiDJZ+vs8d4ILXY8QFDp15jkKVPYMKrmWQPThghM5DhI/pdrtE95q0I73eaKPaF82SD1jQnoFjR/EJFH/GyvX4QbBBn6GSr9zA/qU2nO1N+io8NQrZeWJ3PCQPYQO7ITbY39bCgvKahDzthC6CPaqBKgrKsJl05tYuWfETxo5+8XQxAyZIbdSCO/2DqK9m2oC3ln4wkuW5qS6h96Q5U+ZEVREO0CLKW97VTMrMcLL2MKhPDy35hLrgpcBZTGpj/w9My4E0QEG/y2F34Hk0GLXpFJad+Be0ByHbfpsJBD89ztpz2kjtJMUDHChUZHL/W5a kWbQZUT8 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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 14.06.24 09:56, Barry Song wrote: > On Thu, Jun 13, 2024 at 9:12 PM David Hildenbrand wrote: >> >> On 13.06.24 11:06, Barry Song wrote: >>> On Thu, Jun 13, 2024 at 8:49 PM David Hildenbrand wrote: >>>> >>>> On 13.06.24 10:46, Barry Song wrote: >>>>> On Thu, Jun 13, 2024 at 12:08 PM Barry Song <21cnbao@gmail.com> wrote: >>>>>> >>>>>> From: Barry Song >>>>>> >>>>>> The folio_test_anon(folio)==false case within do_swap_page() has been >>>>>> relocated to folio_add_new_anon_rmap(). Additionally, two other callers >>>>>> consistently pass anonymous folios. >>>>>> >>>>>> stack 1: >>>>>> remove_migration_pmd >>>>>> -> folio_add_anon_rmap_pmd >>>>>> -> __folio_add_anon_rmap >>>>>> >>>>>> stack 2: >>>>>> __split_huge_pmd_locked >>>>>> -> folio_add_anon_rmap_ptes >>>>>> -> __folio_add_anon_rmap >>>>>> >>>>>> __folio_add_anon_rmap() only needs to handle the cases >>>>>> folio_test_anon(folio)==true now. >>>>> >>>>> My team reported a case where swapoff() is calling >>>>> folio_add_anon_rmap_pte *not* folio_add_anon_rmap_ptes >>>>> with one new anon (!folio_test_anon(folio)). >>>>> >>>>> I will double check all folio_add_anon_rmap_pte() cases. >>>> >>>> Right, swapoff() path is a bit special (e.g., we don't do any kind of >>>> batching on the swapoff() path). >>>> >>>> But we should never get a new large anon folio there, or could that now >>>> happen? >>> >>> My team encountered the following issue while testing this RFC >>> series on real hardware. Let me take a look to identify the >>> problem. >>> >>> [ 261.214195][T11285] page:000000004cdd779e refcount:4 mapcount:1 >>> mapping:00000000ba142c22 index:0x1 pfn:0x1b30a6 >>> [ 261.214213][T11285] memcg:ffffff8003678000 >>> [ 261.214217][T11285] aops:swap_aops >>> [ 261.214233][T11285] flags: >>> 0x2000000000081009(locked|uptodate|owner_priv_1|swapbacked|zone=1|kasantag=0x0) >>> [ 261.214241][T11285] page_type: 0x0() >>> [ 261.214246][T11285] raw: 2000000000081009 0000000000000000 >>> dead000000000122 0000000000000000 >>> [ 261.214251][T11285] raw: 0000000000000001 00000000000d84b3 >>> 0000000400000000 ffffff8003678000 >>> [ 261.214254][T11285] page dumped because: >>> VM_WARN_ON_FOLIO(!folio_test_anon(folio)) >>> [ 261.214257][T11285] page_owner tracks the page as allocated >>> [ 261.214260][T11285] page last allocated via order 0, migratetype >>> Movable, gfp_mask 0x2140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid >>> 11285, tgid 11285 (swapoff), ts 261214177545, free_ts 261151875699 >>> [ 261.214268][T11285] post_alloc_hook+0x1b8/0x1c0 >>> [ 261.214284][T11285] prep_new_page+0x28/0x13c >>> [ 261.214291][T11285] get_page_from_freelist+0x198c/0x1aa4 >>> [ 261.214298][T11285] __alloc_pages+0x15c/0x330 >>> [ 261.214304][T11285] __folio_alloc+0x1c/0x4c >>> [ 261.214310][T11285] __read_swap_cache_async+0xd8/0x48c >>> [ 261.214320][T11285] swap_cluster_readahead+0x158/0x324 >>> [ 261.214326][T11285] swapin_readahead+0x64/0x448 >>> [ 261.214331][T11285] __arm64_sys_swapoff+0x6ec/0x14b0 >>> [ 261.214337][T11285] invoke_syscall+0x58/0x114 >>> [ 261.214353][T11285] el0_svc_common+0xac/0xe0 >>> [ 261.214360][T11285] do_el0_svc+0x1c/0x28 >>> [ 261.214366][T11285] el0_svc+0x38/0x68 >>> [ 261.214372][T11285] el0t_64_sync_handler+0x68/0xbc >>> [ 261.214376][T11285] el0t_64_sync+0x1a8/0x1ac >>> [ 261.214381][T11285] page last free pid 90 tgid 90 stack trace: >>> [ 261.214386][T11285] free_unref_page_prepare+0x338/0x374 >>> [ 261.214395][T11285] free_unref_page_list+0x84/0x378 >>> [ 261.214400][T11285] shrink_folio_list+0x1234/0x13e4 >>> [ 261.214409][T11285] evict_folios+0x1458/0x19b4 >>> [ 261.214417][T11285] try_to_shrink_lruvec+0x1c8/0x264 >>> [ 261.214422][T11285] shrink_one+0xa8/0x234 >>> [ 261.214427][T11285] shrink_node+0xb38/0xde0 >>> [ 261.214432][T11285] balance_pgdat+0x7a4/0xdb4 >>> [ 261.214437][T11285] kswapd+0x290/0x4e4 >>> [ 261.214442][T11285] kthread+0x114/0x1bc >>> [ 261.214459][T11285] ret_from_fork+0x10/0x20 >>> [ 261.214477][T11285] ------------[ cut here ]------------ >>> [ 261.214480][T11285] WARNING: CPU: 3 PID: 11285 at mm/rmap.c:1305 >>> folio_add_anon_rmap_ptes+0x2b4/0x330 >>> >>> [ 261.215403][T11285] pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT >>> -SSBS BTYPE=--) >>> [ 261.215423][T11285] pc : folio_add_anon_rmap_ptes+0x2b4/0x330 >>> [ 261.215428][T11285] lr : folio_add_anon_rmap_ptes+0x2b4/0x330 >>> [ 261.215433][T11285] sp : ffffffc0a7dbbbf0 >>> [ 261.215437][T11285] x29: ffffffc0a7dbbbf0 x28: ffffff8040860a08 >>> x27: ffffff80db480000 >>> [ 261.215445][T11285] x26: fffffffe04cc2980 x25: ffffff808f77f120 >>> x24: 0000007b44941000 >>> [ 261.215452][T11285] x23: 0000000000000001 x22: 0000000000000001 >>> x21: fffffffe04cc2980 >>> [ 261.215459][T11285] x20: ffffff80db480000 x19: fffffffe04cc2980 >>> x18: ffffffed011dae80 >>> [ 261.215465][T11285] x17: 0000000000000001 x16: ffffffffffffffff >>> x15: 0000000000000004 >>> [ 261.215471][T11285] x14: ffffff82fb73fac0 x13: 0000000000000003 >>> x12: 0000000000000003 >>> [ 261.215476][T11285] x11: 00000000fffeffff x10: c0000000fffeffff x9 >>> : 0d46c0889b468e00 >>> [ 261.215483][T11285] x8 : 0d46c0889b468e00 x7 : 545b5d3935343431 x6 >>> : 322e31363220205b >>> [ 261.215489][T11285] x5 : ffffffed013de407 x4 : ffffffed00698967 x3 >>> : 0000000000000000 >>> [ 261.215495][T11285] x2 : 0000000000000000 x1 : ffffffc0a7dbb8c0 x0 >>> : ffffff8068c15c80 >>> [ 261.215501][T11285] Call trace: >>> [ 261.215504][T11285] folio_add_anon_rmap_ptes+0x2b4/0x330 >>> [ 261.215509][T11285] __arm64_sys_swapoff+0x8cc/0x14b0 >>> [ 261.215516][T11285] invoke_syscall+0x58/0x114 >>> [ 261.215526][T11285] el0_svc_common+0xac/0xe0 >>> [ 261.215532][T11285] do_el0_svc+0x1c/0x28 >>> [ 261.215539][T11285] el0_svc+0x38/0x68 >>> [ 261.215544][T11285] el0t_64_sync_handler+0x68/0xbc >>> [ 261.215548][T11285] el0t_64_sync+0x1a8/0x1ac >>> [ 261.215552][T11285] ---[ end trace 0000000000000000 ]--- >> >> Ah, yes. in unuse_pte(), you'll have to do the right thing if >> !folio_test(anon) before doing the folio_add_anon_rmap_pte(). >> >> You might have a fresh anon folio in the swapcache that was never mapped >> (hopefully order-0, otherwise we'd likely be in trouble). > > Yes. It is order-0 > > [ 261.214260][T11285] page last allocated via order 0, migratetype > > Otherwise, we would have encountered this VM_WARN_ON_FOLIO? > > __folio_add_anon_rmap() > { > ... > VM_WARN_ON_FOLIO(folio_test_large(folio) && > level != RMAP_LEVEL_PMD, folio); > ... > } > > Given that nobody has ever reported this warning, I assume all callers > using folio_add_anon_rmap_pte(s) are right now safe to move to ? Yes, and we should likely add a VM_WARN_ON_ONCE() here that we have a small folio if !anon. If that ever changes, we can assess the situation. Only swap created "new" anon folios without properly calling the right function so far, all other code handles that correctly. -- Cheers, David / dhildenb