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 A42D4C79FB7 for ; Wed, 9 Sep 2026 15:52:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AED7D6B008A; Wed, 9 Sep 2026 11:52:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A777C6B0093; Wed, 9 Sep 2026 11:52:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 917436B0095; Wed, 9 Sep 2026 11:52:34 -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 566D66B008A for ; Wed, 9 Sep 2026 11:52:34 -0400 (EDT) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 8E7EDA425B for ; Wed, 9 Sep 2026 15:52:33 +0000 (UTC) X-FDA: 85194666186.04.61C7C61 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf01.hostedemail.com (Postfix) with ESMTP id AE8C94000E for ; Wed, 9 Sep 2026 15:52:31 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FQBsMdka; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf01.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788969151; 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=u91uFesTnFbGp/0SROsL3Fce0KUie7u3CWxoraS7oAQ=; b=jsFMcFzANBjy6Ho0876zbP6QMyxuMbdn7Z/rquCQITdFgDjaq83QVXo1oXEJErwzpBucOv wAArRGkCGuwdKC1M0dv9DB+Eaf3A2lxTn3bJU3wlEclcG3npW62VSJq4m71v+XT3hCgH+k ypkHImshqMFXhb1J7/v86fwhWBY3vMI= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788969151; b=mI2H9rKHgBhgGpj7sj6tbwyRtWx56Qqr5y1870bDvCk87qAf4NB4TnBeEL8bCWJXpY02it 6cKcHU3SuVUekHRchi05niHXiJoS9N4W/R7f6lsc14/7UtAux1Bf4kSzDD84kPhrtb1vB3 kTyE77kM9nWuZ0mEPa6/XCSGWL4Yrb4= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FQBsMdka; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf01.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C50C643CD0; Wed, 9 Sep 2026 15:52:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9D481F00A3A; Wed, 9 Sep 2026 15:52:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788969150; bh=u91uFesTnFbGp/0SROsL3Fce0KUie7u3CWxoraS7oAQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=FQBsMdka6q3yJt4PU5XM/w8brLU7gUN6lqri9XYHBVnNyH62B5rbtWvnsDcuDDstR yUYGausmecFcZ01xcp9jcXh6Ho5wsTQC/KHLYEhhxTdAcpoZL5xbh02s+2mdoJKJ3H Cp0MTYHR4h+lAxicsGveorC67zzpo0UPgSBxoxYCK68UEpTQW1y77SCx6ZwpV/csrz raXx29Z1Se41gtjEI1U2vIhXIn7MET8plb8HrdSDx/6+Iyyu8xI3OQ7cdLk6+LSork xm7TREyRSVsrnCKckGjwZONbqeCoEzk9VmOK+gkVKpkdILm+SY4p/AoaYniCXdOkqG ruQAOmRiKrwxg== Message-ID: <13f2c56c-b55b-4245-8190-7038f4eab98f@kernel.org> Date: Wed, 9 Sep 2026 17:52:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 18/45] KVM: guest_memfd: Handle lru_add fbatch refcounts during conversion safety check To: ackerleytng@google.com, aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , John Hubbard , Peter Xu , tarunsahu@google.com, Randy Dunlap , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Fuad Tabba Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev References: <20260830-gmem-inplace-conversion-v12-0-85e5fd25252a@google.com> <20260830-gmem-inplace-conversion-v12-18-85e5fd25252a@google.com> 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: <20260830-gmem-inplace-conversion-v12-18-85e5fd25252a@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AE8C94000E X-Stat-Signature: eoopz7cwo3ux4mt6p5oy9z864yn531e3 X-HE-Tag: 1788969151-462800 X-HE-Meta: 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 BDl0CWMv VA+zKW846ygyxNzYflLY8TnqUf0uRe7t9QmhsV+U4tSolcj+Ldl0SB+Z6W5RvXIeaGUUuWypcBLMjz4fU7+ugL0/pjjZq8oc/GYTI+t7lHgprXgRK5sAYSxnJ8pdZIDY78CsaCd/PGASeAKXwSTK7/A44U8R7HHcF7J3LE9lYti89+kmT7CIjqsnwpjD/hGNcB/q+XzqlpejEyelRjKsqWto3FFVk00avVsYl2q8Twwxr6VunOkMU49IjwFqTXW4JxwZ3gyyes8Pkkg9ja5G72pAmBqA8xaArkT/TAXi5gejnDi5dmrxpvpQswmibtUB6wr/gRhCzSvvo778= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > + > static bool kvm_gmem_has_outstanding_references(struct inode *inode, > pgoff_t start, size_t nr_pages, > pgoff_t *err_index) > { > + enum lru_cache_drained drained = LRU_CACHE_NOT_DRAINED; > struct address_space *mapping = inode->i_mapping; > pgoff_t last = start + nr_pages - 1; > bool has_outstanding = false; > @@ -570,17 +589,12 @@ static bool kvm_gmem_has_outstanding_references(struct inode *inode, > folio_batch_init(&fbatch); > > next = start; > - while (has_outstanding && filemap_get_folios(mapping, &next, last, &fbatch)) { > + while (!has_outstanding && filemap_get_folios(mapping, &next, last, &fbatch)) { > for (i = 0; i < folio_batch_count(&fbatch); ++i) { > struct folio *folio = fbatch.folios[i]; > > - /* > - * Outstanding references are anything other than those > - * from the page cache, plus 1 temporary reference held > - * by filemap_get_folios() in the folio batch. > - */ > - if (folio_ref_count(folio) != folio_nr_pages(folio) + 1) { > - has_outstanding = true; > + has_outstanding = __folio_has_outstanding_references(folio, &drained); > + if (has_outstanding) { > *err_index = max(start, folio->index); > break; > } > Having the folio.c bits go upstream early is certainly cleaner; without Hugh's series an ack from MM maintainers would have been sufficient, though. In any case, on the revised patch with only guest_memfd changes: Reviewed-by: David Hildenbrand (Arm) -- Cheers, David