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b=koQxmrbAtVUkO9f8/pTBo7Der4rnJJhoqBbPvTkFKj+zarXLinuFXlnRIFA+rCrju hClEn3C9CVxkXxukJXiqjcC7jHcKA3fR+gaECf+0AbeEHNs16x5gOViZzy6RS1M1+l AEmdrq6TseUz+V/MCm7ZozMzg+tTfafvsbgYuzYNgwtY4GLy0joJFg/1MhS8o67l3q NFznEVEvGdoobpbNkPcCzuLLkOrvfbfhXKOWrVfEHO9mfIvOOUFdE+hy34h4OMJCmt 0hDsjDQin7RVR3VAd22zSTwHNoF6RIhNRwVXm+xmS7Ut+0khjAJ1Mz5v+xK4uoQ1XB W5MQdFyHoDRew== Message-ID: Date: Wed, 19 Aug 2026 10:01:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm, swap: ratelimit bad swap entry reports To: Andrew Morton , Breno Leitao Cc: Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Miaohe Lin , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, stable@vger.kernel.org References: <20260818-swap_part_one-v1-1-a4fc58119fc0@debian.org> <20260818122844.71988535d6380ba67e8a2b1a@linux-foundation.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260818122844.71988535d6380ba67e8a2b1a@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: E856A140008 X-Stat-Signature: ic697zpe1o3q7q8wwr6eiwihfzehiehb X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1787126509-946089 X-HE-Meta: U2FsdGVkX1+HthcHHRhvRCM8tXHZLaS9+n9aIHXQgoycBDuX9+U5OoYrPVLG4htAWYlMvb0ywTaXlfuC8vuo7m/B0YoO+ui/kYKsu6beuYTm8S1NZbHVIA1KtRv8+4sYOJzszpVnWUYObDudm7iPwZE1nKWRNe60MSdTthDWmnL0fK+jDx2fseW9PHVIfx9JaYZyAfBVWv+tPQpZVpL9w4jhqUEfOFRWWdlC9j/oxz+kUHXWHmpJnJv9UdGkN0sFGolOZ73iiJ+K0d8ExaFk7rFq9FImpNZqKUGBC/WTVqF5ZkH+PzkEwpkZyTnAuZCodxRkPy/cVp5wmjyOdbzUYHq9gmxmV375Umq8sAeQ2cqXcrnVPtdRpFR25Z8zQJtR0bYnibXeMhcd6MyjmM2oaj/M3nHpnHn75BR2mGmWI1prIh6kqoayp8rtE8Sv6Wt7ey5Dn87495Yne65osJqZpZuINjj1HOQY+BNzU32yEUen5mxYZQm07rmQCjkUMlRPFZ78KyRMKFKU2n871V+igOCY+8yg3aT7KbZ11Z9y/O4XRzZd5d7booWPinr4cq2jZ32IemBMaeqwWHi0ltnFS6YrgSE+QAlwtTXed+/zSCzyr1DxeKlNVqpc+g0/ENSibyoKJ1ZBERkGH6EeG7b+eEzJZ47VhM8CMrcFITa/VzbrSyhjr7YhUwN+YvcXwlkCt+PfgYgtG97fnf6juNr3LipHDlBdncdeXv9V2mdztmOx12RfUPavcOpcsSmSsO8XHqVxUSLtdc6ajyD3UZCSSewLH9M+BBYNZJeTlFFqeky8YnMVNJLI1OG8jWqaFj+5bKRWs9xlRo0LcdY9izDpz2ljooEccFYaeOfGbPjIdgoEYBE8U269O7n/Duqvu06Y71JWmmGoaK0ppCbydc9EVoiqhLOde6z0b3HT84cZr1RaeEZ+WH2NcEhbnBKL+a3tyGbpVoDnUYm9YXMojbv /JnSqHR1 QG4zie/zhm4nMsg3Z8s0WBfEPtf/BQ69XMC7V5KNS9ZKKE4yCUKbJtDxtyJ20nATdsbQ9WbifBPchSC9jfzAB7vpVYwWmLoJNzQ02A/o0e4TZxmV9g4O0CHd4bYKCwapdZbP/9d2y00jHq9QgYjK98mgzBq/+t/QpIPpAkITbTTzVh+gL2Q2hUTBwryFrBu4jogwF941Z2J9FRavZqRUmaENgGQtNQb1kx5Y7VEZ0mk7wfQ8DSMtxBPJUaccWjSQvpoKTp3X4+8JkAXuorIlVITzBJpktBJqdwsca9CCurqyb9XgIitzsj+mzqUz3Y3aVBFJItjyCt1/2DHxqROGgKpYi/v8Ctj/UitNrAT9t5mkUuT+vYGJs9ffWlA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/18/26 21:28, Andrew Morton wrote: > On Tue, 18 Aug 2026 02:03:40 -0700 Breno Leitao wrote: > >> A corrupt page table hands the same bogus entry to get_swap_device() on >> every access to the mapping, and every rejection is logged. One machine >> logged 6185620 copies of the same line in a few hours. >> >> swap_dup_entry_direct() prints the same message from the fork path, once >> per call: the WARN_ON_ONCE() guarding it warns once, the pr_err() inside >> does not. >> >> Rate limit all three prints. > > Sashiko suggests that ratelimiting these might cause pre-existing > problems to become worse: > https://sashiko.dev/#/patchset/20260818-swap_part_one-v1-1-a4fc58119fc0@debian.org > The fist problem it raises is actually fixed by the other patchset this was split off from. I didn't look into the other case. > The problem it's identifying does require that unrelated things go > wrong first - As described above: "A corrupt page table hands the same bogus entry to get_swap_device()", that requires something in the caller to go wrong (page table corruption, similar to how we handle it in other places for present ptes) -- Cheers, David