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Mon, 19 Oct 2026 12:16:04 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-ThreadId: AwmqQQkeUF_N Date: Mon, 19 Oct 2026 18:15:43 +0200 From: "Arnd Bergmann" To: "Jani Nikula" , "Arnd Bergmann" , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "Dave Airlie" , "Simona Vetter" Cc: "Mario Limonciello (AMD)" , "Chenyu Chen" , "Alex Deucher" , "Harry Wentland" , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Message-Id: <3486e0b1-d188-47a9-9de6-7ee5c2cfd097@app.fastmail.com> In-Reply-To: <6c18da11310ced4a7c85ac7862c3f5c67b39891a@intel.com> References: <20261013205223.2396822-1-arnd@kernel.org> <6c18da11310ced4a7c85ac7862c3f5c67b39891a@intel.com> Subject: Re: [PATCH] drm/edid: reduce update_display_info() stack usage Content-Type: text/plain Content-Transfer-Encoding: 7bit On Mon, Oct 19, 2026, at 15:28, Jani Nikula wrote: > On Tue, 13 Oct 2026, Arnd Bergmann wrote: >> From: Arnd Bergmann >> >> The drm_parse_cea_ext() calls into nine individual parser functions >> based on the data format. If all of those get inlined and KASAN_STACK >> is enabled, this can explode the combined stack usage beyond a >> reasonable amount: >> >> drivers/gpu/drm/drm_edid.c: In function 'update_display_info': >> drivers/gpu/drm/drm_edid.c:7040:1: error: the frame size of 1888 bytes is larger than 1536 bytes [-Werror=frame-larger-than=] >> 7040 | } >> | ^ >> >> Mark all of the individual parser functions as noinline_for_stack >> to avoid this and keep their stack frames separate. This reduces >> the stack usage for update_display_info/drm_parse_cea_ext to >> a more manageable 744 bytes, while each parser only adds at most >> 200 bytes on top. > > Is there really no way to tell the compiler to not do silly things in a > more generic way? The problem is really the sanitizers here, which turn off the optimizations that gcc relies on for its normal behavior and which cause additional register pressure for the inserted function calls. Arnd