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 3991330100E; Wed, 24 Jun 2026 16:56:52 +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=1782320214; cv=none; b=pW84VrqB+8trKEkc4wkK5Y5BkfZr/rMjEK12sMxUYOnKLTi8Yu39NsQGOd7uPvVFNXDpbVIId3c3Yo9zigIXIJTci/bwfZiTajuDqHf48gOxHMP+nLhGMHzFDwB6iV/YTJSDufPDpJaeuEqPC2r2DsgypSZpPcNv/QuL3njOhME= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782320214; c=relaxed/simple; bh=Uf1DZ8SIdiccM2WEfWSRxLzrEHTfKhccHNqK178k7z4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WB1XsI62l5/CJ1oNA/0Rfix/fdsEAYFePvGcvkPSLzxIRMts7zOxVxe45ekF6l9rg05+fnmiDEMnapGJPPb921HOvlh0E0xoKvipJB/Cp24SJhZ0KEMRqI2p9B9/RbIAlMtPmSbhFRkdVIuvZ6lDgqlJRWdPLb3iB0DVzUW+UdM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U5PEQtIf; 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="U5PEQtIf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD0DA1F000E9; Wed, 24 Jun 2026 16:56:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782320212; bh=hfnArTYWO+KJaHkHvoimxl4puXmlYhjbhVeVdf2fLao=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=U5PEQtIfyIJSMhx5Q6HZtbJC7AlsXp/MhIWduD5DlmBUkggdI+r9rGz3GzxujjHgw ezINq2WDS+T2ckHxaRBRR30/rWtd1fBT87lAivWesttnmoG5K/LvwyfEuSk9eaA6vq Qi4uUpFAxMGqRYbNTFOmqJEWt6jSHquJCGhgWSYhu7a4mqgfL8fXJESuCikbKUmCVC H6DBBsAQfX72I/zQ2++2BPYX3SjqmXZ23cKCfx6ReyL7pqrE4Q8VGLPZ11AJgWCqY0 U0nQ5sfWjnYbPh3MH4yO8/uPoNyK/dFHQ4Bh5arcw8OGxqSXDZueMPSAemHA9LJNNH 9KL2f/m8hVbXw== Message-ID: <1dc2c6c3-ebce-4646-afc1-d83755537278@kernel.org> Date: Wed, 24 Jun 2026 18:56:50 +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 5/4] virtio_balloon: warn on failed buffer add in stats_handle_request() To: "Denis V. Lunev" , mst@redhat.com Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org References: <549e5456-2b6c-48a5-abe5-ef5425c3f63c@kernel.org> <20260624154001.2733242-1-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: <20260624154001.2733242-1-den@openvz.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/24/26 17:40, Denis V. Lunev wrote: > Like tell_host(), stats_handle_request() ignores the return value of > virtqueue_add_outbuf() and kicks the queue regardless. The same "we > should always be able to add one buffer to an empty queue" assumption > does not hold once the virtqueue has been broken (e.g. on device > shutdown), where the add fails with -EIO. Unlike tell_host() it does > not wait_event() afterwards so it cannot hang, but it still kicks a > queue with nothing queued. > > Warn and bail out on failure, mirroring tell_host() and > virtballoon_free_page_report(). > > Suggested-by: David Hildenbrand > Signed-off-by: Denis V. Lunev > --- > drivers/virtio/virtio_balloon.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 0866a8781f0b..454bbb77331d 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -445,6 +445,7 @@ static void stats_handle_request(struct virtio_balloon *vb) > struct virtqueue *vq; > struct scatterlist sg; > unsigned int len, num_stats; > + int err; > > num_stats = update_balloon_stats(vb); > > @@ -452,7 +453,9 @@ static void stats_handle_request(struct virtio_balloon *vb) > if (!virtqueue_get_buf(vq, &len)) > return; > sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); > - virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); > + err = virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); > + if (WARN_ON_ONCE(err)) > + return; > virtqueue_kick(vq); > } > Reviewed-by: David Hildenbrand (Arm) Although I would just squash #4 and #5. -- Cheers, David