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Mon, 7 Apr 2025 14:01:59 +0000 (UTC) Received: from hydra.redhat.com (unknown [10.45.225.175]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 44192190DB07; Mon, 7 Apr 2025 14:01:52 +0000 (UTC) From: Jocelyn Falempe 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 Cc: Jocelyn Falempe Subject: [PATCH v3 0/2] drm/panic: Add support to scanout buffer as array of pages Date: Mon, 7 Apr 2025 15:42:24 +0200 Message-ID: <20250407140138.162383-1-jfalempe@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C568D18001E X-Stat-Signature: px8zoz1gdojncjz479o74h93usfdcxot X-HE-Tag: 1744034527-248365 X-HE-Meta: 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 nqmSWobi GjoshRRZ/KKROs3DnhMGgPH6Sm06lCUgDZvmr5WtqsuTrja3L7UPCL9UWxB1wI4lnaIfBSbHKkEIKKbE8iSLD9YI9GThKYnEyd1RkwzNAUFfgxjlCgK4DxCYtXG+6t4w/m6/eCVG3t0zNHsM39lObCRGPvYfkIsrlIA40kte7iePgHSoJjDtx/12RGXfwG9l+lUq8BLqFv+0WaF6nIkjFWCiaM52xaCMO1FOl8j2xX/Hyq+Inp7eFd3qkkyZ5JBpkK2a26bETcW5H/12p+up+JOq4z0zhA5Qze+L1iD2CDtlom/N7EqPNL1o5q0egMhqf2qgKwk3VVIR+x+go2NqPQmCAj7BSMe12LJpq4cCLMgj5llxfAQ+2KuaZ6uOtbGQymQyaSo+aLJXSTJz7qGlVROlYzRTb6ljzsux/GEc5Y/hdu/w= 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: 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. [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