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 DA0BF3B8130; Wed, 24 Jun 2026 15:23:56 +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=1782314637; cv=none; b=FNGWF5UI8y1YxPSTaP3PI5J+eXtNHmiUjI8YaRdvpS5e+vWhi8tTbogneYlXyYJZ/bGUyXZZE0DtEmfNaGCX7n0OE1lqH9ArV358PpyN0hP/9a2LDBA/YrRPavlfLhSvcB58KCLbCw2DuSugjtDahgJwyXBOOQbK9ccYDj4DX3w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782314637; c=relaxed/simple; bh=L5f4zah5SsB9Z/Ibk5W7PLtq1ziPevbzXRNl3ysXOsk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sAuQeMjIs53vjoYLN/KyHnXXWfNAO7I4/n/ZHu6tkwOvMk11gOfVprJQyaft59KVoxfBfiFeeyH+Jy/BokenyNKS1q+ROo41OUSCnmF/2Do7+lgUrY5QQ4M0bq9t5guRM65/1I5CSdsvvqhb8lG6GPpTNoLgz3dtNRssHPeeIuE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JRQY7SOu; 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="JRQY7SOu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EA671F000E9; Wed, 24 Jun 2026 15:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782314636; bh=s0VwPTbT9N1RbL2lLSIyXAJGXxm+6tnXaT8HL4W+nXU=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=JRQY7SOuwt7fxUxXPZ7RtJVdiwdtHCsBOM9q82ngHDza93b+FQrSnsjtOskH0aqaz vNdbotTS3hO3hIgeMCx6AMnG1GEtGLhDkN45M4/Tzl38urOscQk9i1dULG1J/kX8NP QgX7oCV8C0AoczpEdKUHndtfucYFv/ooEDVUNNmcCJzvGpH8h5+7SXzeXgPbcYrili SheyDzjd1KO7nO6J9HDsxU3hLKncNk7Oa1N9xX1Q/194I/SnS74Cqrbu6ih31wi9vG 3G7L+CVFc3Ay1w9F8wWWFqw+JFxAhtmzldXh8/k+bLsI+rYVgHWttIoiPlonz0pCo6 TKST7wUv8ioCQ== Message-ID: <76457610-bda4-4714-b888-2f45ad1a21b6@kernel.org> Date: Wed, 24 Jun 2026 17:23:53 +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 3/4] virtio_balloon: quiesce balloon work before 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> <20260624140846.2616797-4-den@openvz.org> <17b01bf9-13d2-4e61-a11a-0b91db2f2731@virtuozzo.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: <17b01bf9-13d2-4e61-a11a-0b91db2f2731@virtuozzo.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/24/26 17:00, Denis V. Lunev wrote: > On 6/24/26 16:55, David Hildenbrand (Arm) wrote: >> On 6/24/26 16:08, Denis V. Lunev wrote: >>> Commit 8bd2fa086a04 ("virtio: break and reset virtio devices on >>> device_shutdown()") added a generic virtio bus .shutdown handler that >>> breaks and resets every virtio device during device_shutdown(), i.e. on >>> reboot and kexec. >>> >>> virtio_balloon provides no .shutdown of its own, so that generic path >>> runs while the balloon's asynchronous work is still armed. 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, for example a kexec based upgrade, into a fatal panic >>> in the middle of device_shutdown(), so the machine never reaches the >>> new kernel. >>> >>> Relaxing that single WARN_ON_ONCE() would only hide the symptom: the >>> inflate/deflate and OOM paths do not warn, they call >>> wait_event(vb->acked, ...) and would instead block forever on a broken >>> queue that can no longer complete. The device has to be quiesced, not >>> just kept quiet. >>> >>> Add a .shutdown handler that quiesces the balloon via the shared >>> virtballoon_quiesce() helper while the device is still alive, and only >>> then breaks and resets it via virtio_device_shutdown(). Unlike >>> virtballoon_remove() the balloon workqueue is not destroyed, as shutdown >>> does not free the device and cancel_work_sync() together with stop_update >>> already prevent any further work from being queued. >>> >>> Fixes: 8bd2fa086a04 ("virtio: break and reset virtio devices on device_shutdown()") >>> Signed-off-by: Denis V. Lunev >>> --- >>> drivers/virtio/virtio_balloon.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >>> index 5b02d9191ac6..26fc3c40d5b2 100644 >>> --- a/drivers/virtio/virtio_balloon.c >>> +++ b/drivers/virtio/virtio_balloon.c >>> @@ -1137,6 +1137,12 @@ static void virtballoon_remove(struct virtio_device *vdev) >>> kfree(vb); >>> } >>> >>> +static void virtballoon_shutdown(struct virtio_device *vdev) >>> +{ >>> + virtballoon_quiesce(vdev->priv); >>> + virtio_device_shutdown(vdev); >>> +} >> I'm curious why virtio_gpu_shutdown() doesn't need that (did not look into the >> details). >> >> Reviewed-by: David Hildenbrand (Arm) >> > I would spend more time with other drivers once we will > done with this. I have strong candidate - virtio-mem. Heh, I briefly checked and it should handle it better I think. If virtqueue_add_sgs() fails, it propagates the error (-EIO?) back to the main loop where we end up in switch (rc) { ... default: /* Unknown error, mark as broken */ dev_err(&vm->vdev->dev, ... vm->broken = true; } And just stop. But I didn't actually look into the details. -- Cheers, David