From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5C31E60A3802 for ; Wed, 11 Nov 2026 21:54:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=QGumbhOm Received: by kanga.kvack.org (Postfix) id 4EBF86B00EF; Wed, 11 Nov 2026 16:54:21 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 49C666B05B0; Wed, 11 Nov 2026 16:54:21 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 389F26B05B1; Wed, 11 Nov 2026 16:54:21 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 109666B00EF for ; Wed, 11 Nov 2026 16:54:21 -0500 (EST) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 88568A03F7 for ; Wed, 11 Nov 2026 21:54:20 +0000 (UTC) X-FDA: 85424192280.26.D7DF4F3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf20.hostedemail.com (Postfix) with ESMTP id BDE371C0004 for ; Wed, 11 Nov 2026 21:54:18 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=QGumbhOm; spf=pass (imf20.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; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794434058; b=pEAcjwQgpheK3OYsX8BWQ6GrClSQadbMKTdK6i2RikkVMd/Q+9GfO377ixuQBllWBedYS4 uPpWgRmnT8T4eahxMar0P1ZEuJ+jBI4VgrWDDepURXYf2JB8AQ/ILsxigIP1Q+zODPDi+0 MVHMJvWIFm//pdeFjy1kmu6+2/l7rSI= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=QGumbhOm; spf=pass (imf20.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=1794434058; 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=dB9rG3yxI/9KOZZCGEA3D79pSB6yMsbFsQ1L/4AJU4A=; b=fojGp0Eh6quCwaX5gMd73pofRvojJRmE5HFs3KSG2jGzGwa792vYDwEhU7lazIjH/DGMbs xUCf2uXLwezcKKjTtZPrzzqB8mcZTrDvDIM8VKAHSVjfgJ8GrDDX1xVSoGr64uU66daxni V1AJK+R8VrvTZcH+DtWKUVfxpcY+KSQ= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 410A663548; Wed, 11 Nov 2026 21:54:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E80D1F00A05; Wed, 11 Nov 2026 21:54:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794434058; bh=dB9rG3yxI/9KOZZCGEA3D79pSB6yMsbFsQ1L/4AJU4A=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=QGumbhOm6Cq5mQ4GhXcM1bIeSh2FhKu6qAGcjDV91fS7iPZ1RM+bqTK+9qusyOlEP uZUwH7N9LRXmKtCCbdrv6Hc6eyFJjbQuURmNZ2Kyc6N9tKgp4yAL9cEfJWzRkokhQ7 iCK/6ESLicH/EM+mOCGRT4FtsroZCGpwwFbtuZkdiQNcFOvgpkjHXu2yh5BULMJlnE 3ODMwqBHd93qMF9obH11mwpm2BbMeIxmGElOwh7c8/L5rYWNMz0uRA+t01H4ynbtR9 xE+Dxv+Xuuu+mbUCpYbYU88eoL8iaSLYtSSxz0Oxl/yHaGXeV4KqLeutclY2kPzIoW X6fAR1OYdseFw== Message-ID: Date: Wed, 11 Nov 2026 22:54:00 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 08/13] mm/migrate_device: fix ksmd oops on a migrated KSM page To: "Lorenzo Stoakes (ARM)" , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , David Rientjes , Shakeel Butt , Andrew Morton , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Nhat Pham , Johannes Weiner , Zi Yan , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Usama Arif , Kairui Song , Balbir Singh , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Kiryl Shutsemau , Yu-cheng Yu , Dave Hansen , Dennis Zhou , Tejun Heo , Christoph Lameter , Peng Fan , Josef Bacik , Chris Mason Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Borislav Petkov (AMD)" , Mark Brown , "Dennis Zhou (Facebook)" , Rick Edgecombe , stable@vger.kernel.org References: <20261111-mason-migrate-et-al-fixes-v1-0-3d2454362e8d@kernel.org> <20261111-mason-migrate-et-al-fixes-v1-8-3d2454362e8d@kernel.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: <20261111-mason-migrate-et-al-fixes-v1-8-3d2454362e8d@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: q5qorcb7awrupopfjtgi1bczfqtwsusx X-Rspamd-Queue-Id: BDE371C0004 X-Rspam-User: X-Rspamd-Server: rspam11 X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794434058-135509 X-HE-Meta: U2FsdGVkX18ypsLXFO3gEHvvVK3Z+olg3F2cOstbxQ7YVyCBdQ47ewcTGG9FxlGRi47Ok8GGeBntBBZliYMh3oT3kbwWlGh/U7yJonhBjYVcty8AGa0hpgl52Hb4xUr0WGhDpmRttXJnl9p4fmVv4JY7t+0ZPQUJsc6nfZIEfLnM2Ni5hqduz3ihvKIWCI/a6mdIJ/3L1Y5cblWL/lBYOPYl5B0WGF4XZdbQj8BJOEBzJCVNf1r1Ga4OIZDW1ew3WlWHOeqzX9kxtpG+U51yI6xorj7+KK4lu+M2ZagzrID5yEKI1AdLLa6C77fYj5OJDnY0UCyudmMY5BOcVyw4ekZqKdIS9WgMeChl7f0zisfXngF90HebmLCtKFbHw7nlqF7Yo9sd02Oa8gLBdfe4ddu0mRmn08DsbIEbxNGWbiiC72v+PljlUWEbhAMHoqhG01dNb+ptgChxl2mg6MffdyK4OOldfxhQHDawNN/Oo7sq6pw3auDzGsJJKdI6QegRxT4shjmmPh4b24GppiEG1Kosuzd60jNZA+uN1aticcChD8EpWr/lzUgsrbxnjcohJFmZ+yzwlbLX3QYrqP8yIwngDIlB618EA2KhSduPzqDwqU/zQhWsRaOoTIpUN44VmXXTQVXn4ItXozJvESd+FJHBRmAnDDOi2RqDRjUw5xSrEzhPFPfJfbhy8FovpXNDlQIlJxVG678Uz6Wl0LstDE/TiFuNtl64PyaTXA01JNOBoAhY3qDnp47Ynse9/9jHCjipe+jMryQtRSZJkNdaZlGOhMbRz1HkO52v30r4KkOe3Ye8nPtEMt2K8H7laSgnSCyLv1VQ+qXCEYQqtWpcpAkYs4vKodmvshEvhpVl2Wd0pnXFOjEmL4QE5WNs9TyPrKRTNmyEKol4HS7XHaCiN597/22K5Y75oKigiklP3acztcPCchAsO9nrPBsdWNEcs16Qz8yFxYZri0dHunN 6i3NfWxC SOKugtLL2epteKsiZjPDPQJQezOBQ3IdFwxauLyi1OuBx1XC/eg/WrSuVyse6phb8vAFTbDNPWOkO3aMmBuGfXYJbd4l7/t/i8XDYPMPkXBoLGobhSZipSF9OHz3Fy/rAT6LZerKzvyYD17qJPVWgczJjK+1Eio8e98Q/zH2YQwZj2/rlhYGa2YHCXe44PkpwEg8E1ZsD884dW9SjRoFmbaXIeHX0YQX150yK/NSsAv9vgmLck7RLADgCSDk3uT1IWFY0gzwlCCrZP259zzaVwO5tP0gaseC5o/AJbqr9wpgmbFS9mhnRBtK5W0aQo3BKoEdoXje4poLy+9IhPtQ6+U9uRA1oP43+3ULyqFEgqyDpKyUkYqIK5HJjfpbe9wnmEaDB7AIewZUFHvKJul7UNfa7rYSM4HXoi7tNNmF072WqgL3igK7JYAVhqg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/11/26 19:13, Lorenzo Stoakes (ARM) wrote: > From: Chris Mason > > After a KSM page is migrated to device private memory, ksmd can oops, > and KSM then stops until reboot. A process that maps the page can also > loop in page faults when it next accesses the page. > > The problem arises because KSM doesn't know not to try to look at device > private memory that does not exist in the direct map. > > Disallow this from happening by explicitly testing for this scenario in > __migrate_device_pages(). > > Fixes: a5430dda8a3a ("mm/migrate: support un-addressable ZONE_DEVICE page in migration") > Cc: > Signed-off-by: Chris Mason > [ ljs: tweak commit message, comment ] > Signed-off-by: Lorenzo Stoakes (ARM) > --- > mm/migrate_device.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/mm/migrate_device.c b/mm/migrate_device.c > index 45e571dbfb4c..7ebd02ec303b 100644 > --- a/mm/migrate_device.c > +++ b/mm/migrate_device.c > @@ -1205,6 +1205,15 @@ static void __migrate_device_pages(unsigned long *src_pfns, > } > > > + /* > + * KSM doesn't know not to try to read device private pages, so > + * disallow the combination. > + */ > + if (folio_is_device_private(newfolio) && folio_test_ksm(folio)) { > + src_pfns[i] &= ~MIGRATE_PFN_MIGRATE; > + goto next; In general, LGTM. I was just wondering if we could reject that earlier. because apparently we already allocated a destination folio :) -- Cheers, David