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 DE9A5EFCD9C for ; Mon, 9 Mar 2026 11:50:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1F2556B0088; Mon, 9 Mar 2026 07:50:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 19FF66B0089; Mon, 9 Mar 2026 07:50:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 082686B008A; Mon, 9 Mar 2026 07:50:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id E95DD6B0088 for ; Mon, 9 Mar 2026 07:50:51 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 82E5A1BEAD for ; Mon, 9 Mar 2026 11:50:51 +0000 (UTC) X-FDA: 84526357902.28.870E0A9 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf30.hostedemail.com (Postfix) with ESMTP id B28AF80004 for ; Mon, 9 Mar 2026 11:50:49 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=doD57pDQ; spf=pass (imf30.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=1773057049; 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=fYvkVpf+IuARLiG1oqR6FUltSosrn34oLN70fxLT9Nw=; b=RrqiZzAGyESufQLl2DhBYO1t4hky+BgUEg+8gBpgi9MZmHSccrDnvP3FTzURx0Sd2OZR0j 2E7wbG0sffzCFafWghD8WeltA1ZSAeeaXWqsdm1ZlmY+gDJokbk7neSOTb2z7w3z9hit94 HKYflmCof2pY+n0AKjdrW0wl7Ky2fhU= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=doD57pDQ; spf=pass (imf30.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; s=arc-20220608; d=hostedemail.com; t=1773057049; a=rsa-sha256; cv=none; b=rD+ibR78V6IEcCKV795pfA89n2HVjmFyYz9p9cd6RZOIF3SsiafTkqtGgxT7Iy7/dh2t/0 sSGuaYvmN9OeC4wTLiPrRV30zRGQF3ZOg70tlxToLKJE49eZMrcK0CPbI56E+xFfroCUuA ZzGoY0Ek2GdOzCY3xpHsQDUWPy/jlHw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 9F3AF4414C; Mon, 9 Mar 2026 11:50:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B42C9C4CEF7; Mon, 9 Mar 2026 11:50:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773057048; bh=MKDoMhatF/8bmNy6+4wMS5v8ebUxjWldeMUyNsD//UI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=doD57pDQPBLH+3BvqxHLNZmaR1BBbeo4If0RPfIqWfW5Z9lEi02liWOf9Tv5JUrie ufUKiMb9aOonEeLiXnITDfuCrjFo2knisrJoDRPa2HHhr6g8Q34rbFcr5+o53EhB8M 16h/9igRBjHnzQ2hS7sn2zNZnATj63YIOQZ9kLADwIU6Gp/u4v3jiTIak7wA7mfvvN H7N6uwroorzCmuYVAqpQkgzQ1JId2xSIUTWrqXr+DUUMeugtAo2SA2Td2567bFhNnl 1sq4SYFMELF9394s1kh9A7kMe7MT5K7PVP5Tgmp8NnZFRSLsW3fP9GfdtSjasR6HXT Cf1PYT7f1gP3A== Message-ID: <577c4725-7eda-4693-a55a-413572541161@kernel.org> Date: Mon, 9 Mar 2026 12:50:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v3 1/4] KVM: guest_memfd: Track amount of memory allocated on inode To: Ackerley Tng , Paolo Bonzini , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Shuah Khan , Jonathan Corbet , Alexander Viro , Christian Brauner , Jan Kara , seanjc@google.com, rientjes@google.com, rick.p.edgecombe@intel.com, yan.y.zhao@intel.com, fvdl@google.com, jthoughton@google.com, vannapurve@google.com, shivankg@amd.com, michael.roth@amd.com, pratyush@kernel.org, pasha.tatashin@soleen.com, kalyazin@amazon.com, tabba@google.com, Vlastimil Babka Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org References: <20260309-gmem-st-blocks-v3-0-815f03d9653e@google.com> <20260309-gmem-st-blocks-v3-1-815f03d9653e@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: <20260309-gmem-st-blocks-v3-1-815f03d9653e@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B28AF80004 X-Stat-Signature: kfthhb6bkuybx8qif3ywg1isrrhqe3ow X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773057049-549264 X-HE-Meta: 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 Z8flRqhP lJ3qCIKBJBwkKUK9xyw6uCmm8tOVHl4xcE1HTyNarfhV5QLTdvRIEy9+txG6mDw6FXL58s8wXiLSMNTG/1SBCepU5XMUZ4cN08BIg/INhe5s8fPclpOZVVa9AlS+uxcJkh7TYrOuepaRxLfXGG/0MWZLT8wawvEZf+G6/e7UFgk3RSJpqf7/vy38NPJ9sm3lv2IN25b8IKsk+Aarddk3GBueDLGEpt/wB7GRS74T6tbBIupnu8emkbIsVrUyGFtxN78hIkVLy7gRK4AGdOiBChW/U3TwZeylnrq++QA8jHKaa4aYDMjwB37fKvSyCA6p1Rh18qT8pJVCL4hU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/9/26 10:53, Ackerley Tng wrote: > The guest memfd currently does not update the inode's i_blocks and i_bytes > count when memory is allocated or freed. Hence, st_blocks returned from > fstat() is always 0. > > Introduce byte accounting for guest memfd inodes. When a new folio is > added to the filemap, add the folio's size. Use the .invalidate_folio() > callback to subtract the folio's size from inode fields when folios are > truncated and removed from the filemap. > > Signed-off-by: Ackerley Tng > --- > virt/kvm/guest_memfd.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index 462c5c5cb602a..77219551056a7 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -136,6 +136,9 @@ static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index) > mapping_gfp_mask(inode->i_mapping), policy); > mpol_cond_put(policy); > > + if (!IS_ERR(folio)) > + inode_add_bytes(inode, folio_size(folio)); > + Can't we have two concurrent calls to __filemap_get_folio_mpol(), and we don't really know whether our call allocated the folio or simply found one (the other caller allocated) in the pagecache? -- Cheers, David