From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6DAC03803C7; Thu, 2 Jul 2026 19:30:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783020632; cv=none; b=uzV+ftV7MhKgZvrWbLfWxe1ohEJ5XvnLNwwUfi4oHKy8umGdX0t5Jnpf5/Ki2tJ9jjBzK8nV6MptlkP78lPcWegEWEwE7tqzqnxvt0PusYnsYfMH5ytWWC4w6HSTM+9VHDtvrW+lYQHbV8rBo3zC7ZAr9HQaprXuKc3d3vaQ6LI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783020632; c=relaxed/simple; bh=sUeDt8hk+2/UcUZ+8uOVVfJw7c+Px1GvrSZTcnyzO04=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ct6TI2g/iVsiE6Bh388SIZduvrxdJfBuwQdaticE79GSj6RWpc3wzlTZdAhg33jZ6J7qFKyhLl+62sXQT+5k0SgM4hapW9PpBhvpgBknSS796UtezomTFSjmmI91NE0To967IMApkLq5NEsCHmuyhLIL04qdiElVoyvAlZZ31/0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DS7rt+zt; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DS7rt+zt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D86551F000E9; Thu, 2 Jul 2026 19:30:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783020631; bh=PAZ6xOJOsgJOvLo0/CGVWaOOeiFezyUSuxLlmtMflNw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=DS7rt+ztB93KrJISsq8MCA6BarZgD3nTmdZ12KKtpImR7AoKx4YY0R0VpuynsJq0k m02w8NacpIjcaDXhPqFJXBM3p6zWhNRn4XzbQSDar0D/Qky5Pz4SrffdmY0WGnJi9N 7YNkI1ILVkwTOl13gGSi5n7hSDnhNJ8odLfdHYbt8XwcQ1ZnE96JWESBzp9Dmuh0Fd ZPkhd6Z/nUAH3FOEH6gQfDTTbPi/WSXw4OAV2VHPG+4Rv6jl64D7JwkXxzBwLevlLp spIiCq85jocKgk+rOdKNW+7CMcAIy9BJufF3gjjPYwsDGvsVXxnUJ4Bvy2Lu9m2mGC DxlzZMFc6axBQ== Message-ID: <00ebb86d-f7b8-4ddc-a17c-c4700cab73a9@kernel.org> Date: Thu, 2 Jul 2026 21:30:26 +0200 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/4] virtio_balloon: quiesce balloon work on device shutdown To: "Denis V. Lunev" , "Denis V. Lunev" , mst@redhat.com Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260624140846.2616797-1-den@openvz.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 On 7/2/26 19:50, Denis V. Lunev wrote: > On 6/24/26 16:08, Denis V. Lunev wrote: >> This email originated from an IP that might not be authorized by the domain it was sent from. >> Do not click links or open attachments unless it is an email you expected to receive. >> Since commit 8bd2fa086a04 ("virtio: break and reset virtio devices on >> device_shutdown()") the virtio bus breaks and resets every virtio device >> during device_shutdown(), i.e. on reboot and kexec. virtio_balloon has no >> .shutdown of its own, so that generic path runs while the balloon's >> asynchronous work is still armed: the free page reporting worker, the >> inflate/deflate and stats workers, the OOM notifier and the free page >> shrinker. >> >> Once the device has been broken, virtqueue_add_inbuf() in >> virtballoon_free_page_report() returns -EIO and trips its WARN_ON_ONCE(). >> On a kernel booted with panic_on_warn that turns an ordinary reboot into a >> fatal panic in the middle of device_shutdown(), so the machine never >> reaches the new kernel. The inflate/deflate and OOM paths do not warn but >> are no better off: they call wait_event(vb->acked, ...) and would block >> forever on a queue that can no longer complete. >> >> This was hit in the field as an intermittent failure of a virtualization >> cluster upgrade: guest storage nodes were rebooted via kexec into the new >> kernel, and the ones whose free page reporting happened to run during >> device_shutdown() panicked (the guests run with panic_on_warn) and never >> came back, stalling the rolling upgrade. The crash dump showed the WARN at >> virtio_balloon.c:216 in a page_reporting kworker, with all the balloon >> virtqueues already broken. >> >> Validated by churning balloon inflate/deflate from the host while >> kexec-rebooting the guest in a loop under panic_on_warn: the unpatched >> kernel reproduces the WARN within a couple of cycles, while the patched >> kernel survives many consecutive kexec cycles cleanly (12/12 in the final >> run, 0 WARNs). checkpatch is clean across the series. >> >> Changes in v2: >> - Add a virtio_device_shutdown() core helper and call it from the balloon >> .shutdown handler instead of open-coding break + synchronize_cbs + reset >> (David Hildenbrand). >> - New patch: make tell_host() warn and bail instead of hanging if a buffer >> add ever fails (David Hildenbrand); kept as a separate patch >> (Michael S. Tsirkin). >> >> v1: https://lore.kernel.org/all/20260622133715.3707707-1-den@openvz.org >> >> Denis V. Lunev (4): >> virtio: add virtio_device_shutdown() helper >> virtio_balloon: factor out virtballoon_quiesce() >> virtio_balloon: quiesce balloon work before device shutdown >> virtio_balloon: warn on failed buffer add in tell_host() >> >> drivers/virtio/virtio.c | 41 ++++++++++++++++++++++----------- >> drivers/virtio/virtio_balloon.c | 40 ++++++++++++++++++++++++-------- >> include/linux/virtio.h | 1 + >> 3 files changed, 59 insertions(+), 23 deletions(-) >> > Hi, David! Hi! :) > > Is this good to go in? I have not seen the confirmation that the > series is taken into your tree. I don't have a tree (yet), and once I have one it will likely be more mm focused :) @MST, I think this is good to go! -- Cheers, David