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 7AC533BED35; Mon, 21 Sep 2026 15:50:11 +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=1790005813; cv=none; b=bOi/ybU7B2rhvpLUimYMB40NuSP6RNksVXiWKq54RoTrsRZCAIZaMm4j/c7HPVY1N8vLXjMt6HvCuFOw2HtYo/dqdA5gUj6o6txJtq1C8cdBq24YnRMnh/sManYA/pq9TSCwaiPsZikPxUwQwvGJI6TNtywjk8vQUq0vDVuiCXA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790005813; c=relaxed/simple; bh=HHOV2sHuKbO7q1y40mnJ3BBAhf3V7+LoKvNJ49goYcw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NVu6qhTI/dT9v1wcDSYIQG1vzn4tDfmGPmpwNltUFiOj8aYECDe+3YQGmt/Mb6Hm7R9QGUzbg90bh/VD9jTxWTT3dUbAjQYydlg6UfAW9286MacH341rQfLaBocWbfiFZUluNz/e6K9u1/pYarPmfLhft4FVn2plRPSo+SjQyr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Oh6mIuQh; 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="Oh6mIuQh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A2DE1F000FF; Mon, 21 Sep 2026 15:50:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790005809; bh=zNJc6l1eT2arkxwpoV3EiLXIzBNXwmByVmOhj8b7aKs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Oh6mIuQhm2v+ty5d/2r34B8sYcPUN24dGLKtnmIw7d9PnyuTtkUJ3yk11orWgNjJs H9VGZxSAxkHL5pwAj48a7zPo17bSZSNRLJTe3qYpMx0G4rYK7yI5EtRd2HH1iUC0Gj egaWhIDMDkPWE8YTVUaFwwVPDl91LyGeXYrxF2I9cB9imgatjFfjFRglRVmUD4tEAI 504DfX5RF/T8GUooJ4o4dkeh1DlXaBlZlnQYX4nYtVZ3txwNyhcmYSKld8xl0bFVzw GtR++9gvWM0T1ZllGKUFwQ1Og11M/eONSGjVWzZAOVRSyl6Mlz1rP/2lcqcfYgw6by p0EtdZu0S8kSw== Date: Mon, 21 Sep 2026 08:50:08 -0700 From: Wei Liu To: Sahil Chandna Cc: kys@microsoft.com, haiyangz@microsoft.com, namjain@linux.microsoft.com, mhklinux@outlook.com, hamzamahfooz@linux.microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, lpieralisi@kernel.org, kwilczynski@kernel.org, mani@kernel.org, robh@kernel.org, bhelgaas@google.com, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] PCI: hv: Warn when wait_for_response() waits indefinitely Message-ID: <20260921155008.GA1566687@liuwe-devbox-debian-v2.local> References: <20260914103918.3125157-1-sahilchandna@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260914103918.3125157-1-sahilchandna@linux.microsoft.com> On Mon, Sep 14, 2026 at 03:39:09AM -0700, Sahil Chandna wrote: > A guest can wait indefinitely in wait_for_response() for the host to > send either a rescind message or a packet completion. If the > host does not send either, the guest can remain blocked with no > diagnostic indicating a reason. > This was observed during a guest kernel upgrade in which the > host-side application handling the PCI channel faulted, causing the > guest to never receive the completion request. > Add a warning in wait_for_response() when the wait exceeds > a timeout so that such a hang is visible in the guest's kernel log > and can be correlated with host-side state. > > Suggested-by: Michael Kelley > Reviewed-by: Naman Jain > Signed-off-by: Sahil Chandna Applied. Thanks.