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([2a01:e0a:c:37e0:ced3:55bd:f454:e722]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43f233a2c53sm43898445e9.14.2025.04.10.02.06.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Apr 2025 02:06:52 -0700 (PDT) Message-ID: <009a1a7b-594b-4709-b9bc-068b2e6aa922@redhat.com> Date: Thu, 10 Apr 2025 11:06:47 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/2] drm/panic: Add support to scanout buffer as array of pages To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Ryosuke Yasuoka , Javier Martinez Canillas , Wei Yang , Andrew Morton , David Hildenbrand , John Ogness , Thomas Gleixner , linux-mm@kvack.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20250407140138.162383-1-jfalempe@redhat.com> From: Jocelyn Falempe In-Reply-To: <20250407140138.162383-1-jfalempe@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: usM6LYCm-FrJmOhbApOouli-7fIymFZgTiM0uK-Eoio_1744276014 X-Mimecast-Originator: redhat.com Content-Language: en-US, fr Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 042624000C X-Stat-Signature: g6csa58dmi3g5mzedoh15ur99ohj7dre X-HE-Tag: 1744276016-471249 X-HE-Meta: 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 Aq3W626S FEosmbopqkPhmrybP61sZ4qMF3/n3YXrTwutCaSRJRvk5J5elFp60kkLS+FA3vs+1rSQ9Chk2QB+CmBlTMFO9Gsk9rbeiNgqjS8F23ICyT3muKW/sn9vVW8vW7w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 07/04/2025 15:42, Jocelyn Falempe wrote: > Some drivers like virtio-gpu, don't map the scanout buffer in the > kernel. Calling vmap() in a panic handler is not safe, and writing an > atomic_vmap() API is more complex than expected [1]. > So instead, pass the array of pages of the scanout buffer to the > panic handler, and map only one page at a time to draw the pixels. > This is obviously slow, but acceptable for a panic handler. > As kmap_local_page() is not safe to call from a panic handler, > introduce a kmap_local_page_try_from_panic() that will avoid unsafe > operations. I applied both patches to drm-misc/drm-misc-next. Thanks for the reviews. > > [1] https://lore.kernel.org/dri-devel/20250305152555.318159-1-ryasuoka@redhat.com/ > > v2: > * Add kmap_local_page_try_from_panic() (Simona Vetter) > * Correctly handle the case if kmap_local_page_try_from_panic() > returns NULL > * Check that the current page is not NULL before trying to map it. > * Add a comment in struct drm_scanout_buffer, that the array of > pages shouldn't be allocated in the get_scanout_buffer() callback. > > v3: > * Replace DRM_WARN_ONCE with pr_debug_once (Simona Vetter) > * Add a comment in kmap_local_page_try_from_panic() (Thomas Gleixner) > > Jocelyn Falempe (2): > mm/kmap: Add kmap_local_page_try_from_panic() > drm/panic: Add support to scanout buffer as array of pages > > drivers/gpu/drm/drm_panic.c | 142 +++++++++++++++++++++++++++++-- > include/drm/drm_panic.h | 12 ++- > include/linux/highmem-internal.h | 13 +++ > 3 files changed, 160 insertions(+), 7 deletions(-) > > > base-commit: fbe43810d563a293e3de301141d33caf1f5d5c5a