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 1413CFF8860 for ; Mon, 27 Apr 2026 16:07:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7AADD6B008A; Mon, 27 Apr 2026 12:07:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 782046B008C; Mon, 27 Apr 2026 12:07:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 698446B0099; Mon, 27 Apr 2026 12:07:04 -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 59D696B008A for ; Mon, 27 Apr 2026 12:07:04 -0400 (EDT) Received: from smtpin17.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 5414D121932 for ; Mon, 27 Apr 2026 15:49:40 +0000 (UTC) X-FDA: 84704770920.17.2635AE1 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf29.hostedemail.com (Postfix) with ESMTP id 8E760120014 for ; Mon, 27 Apr 2026 15:49:38 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MI6yBmVH; spf=pass (imf29.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1777304978; 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=kQ+PgdM1PbtfpIYyny31IM2+kRZt1X8KXnqjpAcJE5g=; b=dxtdv/wDgJ/tJs7lWLQmorh/2N6/PVFlq8DmYAePCEEa6XifDerkuwp6IoZla4s+yaKABL +pCfOAMV9l3USIo7xaDbBGxNOMlRqfCIpLTdUJEQWF6u7xrAJOdXV2kmmVQKEL6r1VqXMV rSRHDxcquqZgajPUjrx6uQdmtCGNUtM= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MI6yBmVH; spf=pass (imf29.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1777304978; a=rsa-sha256; cv=none; b=ahrCVmd76Wrn1JJ37HFWCKJ70A5xe3V/K+T1qgWGKlJt7C1YGPknqJXJBY4nBmGN6R0Gir WkraJougHzeAmdqppV00HIPl1wh+ZgdHZov5ckz6NBOa25d26D0DsMb3dPoXPo6CHmLYj+ b3pGWsouMYZ9p+24rFs00Rxjzda4eNg= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 9E03B60126; Mon, 27 Apr 2026 15:49:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A5E7C19425; Mon, 27 Apr 2026 15:49:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777304977; bh=RnyH3VaJp9iG+DCxp6sKhHFXhoXkGIg/w2D9Ek0Oh5Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=MI6yBmVHD6NdSnTMBO36N9sU6nMr/OjWEqGqd2jCLjCEWVVf7dk6mjXJGk2yQaK+E PhAYxUVn5EV8LITl1X+gPSXptKRIM68RrM34vUt2DrcVNMQao53KTVeexPSpg28oD3 f0L2Wus9WpPXxriMmieKZnpDtIBoXuIfbtGyEw9UGVFgV4dr1WPwrtXnNPuVkTAPhX d0LlPk1CCsyBnddzt+4T76XT6w7AfRcUNgeHf3g8/28A86Jer16wSp+KT0ISHT+EgH O4pOx9y4K1R9LRkKGLNNOayXWpdALpsycItvZHn9moremGmL8FZrXgwn+NY/5Arsfd IEXCtXz5ZIQlw== Message-ID: <9d365395-051a-436b-9017-352ebc889770@kernel.org> Date: Mon, 27 Apr 2026 17:49:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 2/4] mm/memory-failure: add panic option for unrecoverable pages To: Breno Leitao , Miaohe Lin , Naoya Horiguchi , Andrew Morton , Jonathan Corbet , Shuah Khan , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com References: <20260424-ecc_panic-v5-0-a35f4b50425c@debian.org> <20260424-ecc_panic-v5-2-a35f4b50425c@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: <20260424-ecc_panic-v5-2-a35f4b50425c@debian.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 8E760120014 X-Rspamd-Server: rspam06 X-Stat-Signature: dud4g1xgqtu7ijecspu5y1bfymtumod3 X-HE-Tag: 1777304978-106472 X-HE-Meta: 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 /WvpaaYi K6/1td0X3SY7L0iIPDJDE0Q1uxOdtQ9QUTXaTis1046ry8nu2VuR0lTNvN8xNmRAv54bp8bD+9qUDAym7I+G4lrkXOgp3HIARZxkknXPEemOgMrOwW91YAtCuHJcxt9bPANicEtN2zeYEZ55NMwJ5vJNpPvpuZtpFGsM8X7D//4wPl6jiSodJHMZAZ2qpq1r3zqU57GcighpMxcawp4OKVoj2cP3UlUKjeBZnX3Jx68++I5Uhku0rN3tgilpnqJel0ocqSOFu/olwAbe695oCyRoj5raQy5j02L7Ys6ZPiy7QgXJBi5YKIq7+0W/VyEESWQ90xFOcnD0a97k= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > + switch (type) { > + case MF_MSG_KERNEL: > + case MF_MSG_UNKNOWN: > + return true; > + case MF_MSG_KERNEL_HIGH_ORDER: > + /* > + * Rule out a concurrent buddy allocation: give the > + * allocator a moment to finish prep_new_page() and > + * re-check. A genuine high-order kernel tail page stays > + * unowned; an in-flight allocation will have bumped the > + * refcount, attached a mapping, or placed the page on > + * an LRU by now. > + */ > + p = pfn_to_online_page(pfn); > + if (!p) > + return true; > + /* > + * Yield so a concurrent allocator on another CPU can > + * finish prep_new_page() and have its writes become > + * visible before we resample the page state. > + */ > + cpu_relax(); > + return page_count(p) == 0 && > + !PageLRU(p) && > + !page_mapped(p) && > + !page_folio(p)->mapping && > + !is_free_buddy_page(p); I don't get what you are doing here. The right way to check for a tail page is not by checking the refcount. Further, you are not holding a folio reference? If so, calling page_mapped/folio_mapped is shaky. On concurrent folio split you can trigger a VM_WARN_ON_FOLIO(). Maybe folio_snapshot() is what you are looking for, if you are in fact not holding a reference? -- Cheers, David