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Peter Anvin" , Andy Lutomirski , Xin Li , Peter Zijlstra , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Uladzislau Rezki , Kees Cook , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 00/13] Dynamic Kernel Stacks Message-ID: References: <20260424191456.2679717-1-stevensd@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 04-24 12:41, Dave Hansen wrote: > On 4/24/26 12:14, David Stevens wrote: > > The question is then: is this approach something that is fundamentally > > untenable in the kernel > > Yes. Fundamentally untenable. > > Not allowing stack faults has been a wonderful simplification. It's one > of those things that just plain makes the kernel easier to maintain. > Saving low single digits of system memory is not exactly making me eager > to go back to the harder-to-maintain days. > > I seriously doubt that this 1% is the lowest hanging fruit for memory > bloat on these systems. ;) This true until, in a fleet of millions of machines, you encounter a one-in-a-billion chance of a stack overflow. You are then forced to double the statically allocated kernel stacks on every machine, paying a memory tax even though 99.999..% of threads never exceed 4K. This overhead accumulates to petabytes of wasted capacity. Pasha