From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5C204C5CFDB for ; Wed, 12 Aug 2026 11:03:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 471CE6B00E1; Wed, 12 Aug 2026 07:03:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 448EC6B0145; Wed, 12 Aug 2026 07:03:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 33ADD6B0146; Wed, 12 Aug 2026 07:03:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0FDDC6B00E1 for ; Wed, 12 Aug 2026 07:03:54 -0400 (EDT) Received: from smtpin07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 1C307802A9 for ; Wed, 12 Aug 2026 11:03:52 +0000 (UTC) X-FDA: 85092332304.07.720254B Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf31.hostedemail.com (Postfix) with ESMTP id 48A162000B for ; Wed, 12 Aug 2026 11:03:50 +0000 (UTC) Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=g+VTxEFC; spf=pass (imf31.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786532630; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=lSfl6FO5TgTynyqKLLvS/Rpyer3P417NsRPMdDTQcEQ=; b=r2OD9PNCgCq4DSglcsmZzpzyweEvmZCthShGzxKbSaSR1bTNMoWm9TSJRtPBXUoYQ5l65s OXEX5pj+rTBZBkfZSQxMyByu1kcnpumPMRhHQK3TD3IfUW+IyQgXKfzJkeq/bl5uWDubZu wUbSonmxvetyV3KCNy3v04nVt9wSYcQ= ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=g+VTxEFC; spf=pass (imf31.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786532630; b=Cl2hDrgm7Eamq7g9yflD5PwELf05o3fkCrkRN7PGEpm73UzZAh7R9FaKIplm8QvbRB5eE+ Xi4LrmOKep0KHvlqyYwpnPTNa93faIFY0Vv/Grm7yQ7KFgMHDUPcXdZ0Ulbn8cX2UivpZn 6JyCex01RGZTWZAUkrWaYzYOwqR9ZqM= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 7247540781; Wed, 12 Aug 2026 11:03:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1209F1F000E9; Wed, 12 Aug 2026 11:03:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786532629; bh=lSfl6FO5TgTynyqKLLvS/Rpyer3P417NsRPMdDTQcEQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=g+VTxEFC7LgOdvykX9xewDfRpD/O/lq5BU5xoEF6ouwQ8lF1gGNsURm+eX7md6F0a vJ+yU1rKaW/0sPyuMcHlANbPiA4Nuj07Q7d3hi6FR+c3DXPwEY1w4NxdOCrdhBa/El zy1sWCfn50C6/0UUZqey1bZkBq7Kc9HPWJwjSfMbBn02r4qB9OJn5BzLHmqVrKeNqF Y0k79yd+/bRga4HHz70t/dfL5F5Kp39fGtesBp1dQynHdxtUYayrcAqci79g1xPxgo p7VrczjwjbrVNkuEIsvWcjM0Zo8DFvXc5JFqniHaRKHVBt2K0deAeqD4xDds4STK5B 1EDHQ3BTDX1HQ== Message-ID: Date: Wed, 12 Aug 2026 13:03:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/3] mm: fail the fault on a malformed swap entry instead of retrying it To: Pedro Falcato , Breno Leitao Cc: Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Hugh Dickins , Baolin Wang , Peter Xu , Johannes Weiner , Yosry Ahmed , Chengming Zhou , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com References: <20260810-swap-v1-0-375ef0767206@debian.org> <20260810-swap-v1-3-375ef0767206@debian.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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 48A162000B X-Stat-Signature: rnnojrd77txxygn4ohw96oo1oucsb4it X-Rspam-User: X-HE-Tag: 1786532630-667043 X-HE-Meta: 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 hUvDBrmR SrDbBm95hpvTFfx4KTeCxWOR5MEgNWaOp+EJA1PFnAaTunyelg7fNznoob4sHg8Me2dakWLuZJKJ8i2DBkw8q1a7Wzxvm0cUnh0PVgiXs6M+mDRT4cbjhvket3xNqgKm0FJE504gFa9UM9lN7XxtLzu8acetP+jY9nliyv97mwaoxbUUwL7cis5hJjpIfj7qBjJ/FxUooQaED++AB72/4jyLOeVpqW0QhOYntWev7CZbAy2iBKGUEBAsp5niKe4KY2iv/ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/12/26 12:59, Pedro Falcato wrote: > On Mon, Aug 10, 2026 at 09:26:51AM -0700, Breno Leitao wrote: >> do_swap_page() returns 0 when get_swap_device() fails, which the fault >> handler reads as "handled". For an entry that can never become valid >> the retry takes the same fault again, so the thread spins until it is >> killed. >> >> Return VM_FAULT_SIGBUS for a malformed entry, as the sibling arm >> already does for an unrecognised non-swap entry. A NULL return still >> means swapoff, which is still worth retrying. > > What kind of SIGBUS do you get from this? as in the si_code. Out of all > the options > > #define BUS_ADRALN 1 /* invalid address alignment */ > #define BUS_ADRERR 2 /* non-existent physical address */ > #define BUS_OBJERR 3 /* object specific hardware error */ > /* hardware memory error consumed on a machine check: action required */ > #define BUS_MCEERR_AR 4 > /* hardware memory error detected in process but not consumed: action optional*/ > #define BUS_MCEERR_AO 5 > > I would say this would fit none of them. The default (AFAICT) would be > BUS_ADRERR, and I think that one is quite overloaded with meaning (namely, > with regards to memory-mapped IO past EOF, or EIO on file IO). I wouldn't > love to also use it for this, IMO. Note that what is discussed here that should usually happen unless kernel bug. So I don't think we have to worry about the details here, really. It's similar to the VM_FAULT_SIGBUS handling earlier in the function after the print_bad_pte(). -- Cheers, David