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([2a01:e0a:c:37e0:8998:e0cf:68cc:1b62]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43783d325f7sm11303724f8f.8.2026.02.12.02.10.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Feb 2026 02:10:04 -0800 (PST) Message-ID: <7c6933fc-663d-4bf6-8594-c14c4be83c98@redhat.com> Date: Thu, 12 Feb 2026 11:10:02 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] drm/hyperv: During panic do VMBus unload after frame buffer is flushed From: Jocelyn Falempe To: mhklkml@zohomail.com, mhklinux@outlook.com, drawat.floss@gmail.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, ryasuoka@redhat.com Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, stable@vger.kernel.org References: <20260209070201.1492-1-mhklinux@outlook.com> <20260209070201.1492-2-mhklinux@outlook.com> <002601dc9baa$517d8b40$f478a1c0$@zohomail.com> Content-Language: en-US, fr In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 12/02/2026 10:49, Jocelyn Falempe wrote: > On 12/02/2026 00:01, mhklkml@zohomail.com wrote: >> From: Jocelyn Falempe Sent: Wednesday, February >> 11, 2026 1:54 PM >> >> But for this patch, the issue is that drm_panic() never gets called if >> CONFIG_PRINTK >> isn't set. In that case, kmsg_dump_register() is a stub that returns >> an error.  So >> drm_panic_register() never registers the callback to drm_panic(). And if >> drm_panic() isn't going to run, responsibility for doing the VMBus unload >> must remain with the VMBus code. It's hard to actually test this case >> because >> of depending on printk() for debugging output, so double-check my >> thinking. > > Ok you're right. I changed from > atomic_notifier_chain_register(&panic_notifier_list, ...) to > kmsg_dump_register() in the v10 of drm_panic. > > So I should either make DRM_PANIC depends on PRINTK, or call > atomic_notifier_chain_register() if PRINTK is not defined. > > As I think kernel without PRINTK are uncommon, I'll probably do the > first solution. > FYI, I just sent the corresponding change: https://patchwork.freedesktop.org/series/161544/ Best regards, -- Jocelyn