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Wysocki" , Danilo Krummrich , Andrew Morton , linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-modules@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] kernel.h: drop STACK_MAGIC macro Message-ID: References: <20251129195304.204082-1-yury.norov@gmail.com> <20251129195304.204082-2-yury.norov@gmail.com> <3e7ddbea-978f-44f7-abdd-7319908fd83c@kernel.org> Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3e7ddbea-978f-44f7-abdd-7319908fd83c@kernel.org> On Mon, Dec 01, 2025 at 10:38:01AM +0100, Christophe Leroy (CS GROUP) wrote: > > > Le 29/11/2025 à 20:53, Yury Norov (NVIDIA) a écrit : > > The macro is only used by i915. Move it to a local header and drop from > > the kernel.h. > > At the begining of the git history we have: > > $ git grep STACK_MAGIC 1da177e4c3f41 > 1da177e4c3f41:arch/h8300/kernel/traps.c: if (STACK_MAGIC != > *(unsigned long *)((unsigned long)current+PAGE_SIZE)) > 1da177e4c3f41:arch/m68k/mac/macints.c: if (STACK_MAGIC != > *(unsigned long *)current->kernel_stack_page) > 1da177e4c3f41:include/linux/kernel.h:#define STACK_MAGIC 0xdeadbeef > > Would be good to know the history of its usage over time. > > I see: > - Removed from m68k by 3cd53b14e7c4 ("m68k/mac: Improve NMI handler") > - Removed from h8300 by 1c4b5ecb7ea1 ("remove the h8300 architecture") > - Started being used in i915 selftest by 250f8c8140ac ("drm/i915/gtt: > Read-only pages for insert_entries on bdw+") STACK_MAGIC was added in 1994 in 1.0.2. It was indeed used in a couple of places in core subsystems back then to detect stack corruption. But since that people invented better ways to guard stacks. You can check commit 4914d770dec4 in this project: https://archive.org/details/git-history-of-linux