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Thu, 5 Nov 2026 06:55:49 -0500 (EST) Date: Thu, 5 Nov 2026 11:55:48 +0000 From: Kiryl Shutsemau To: "Edgecombe, Rick P" Cc: "Hansen, Dave" , "andrew+kernel@donnellan.id.au" , "luto@kernel.org" , "pasha.tatashin@soleen.com" , "rppt@kernel.org" , "dave.hansen@linux.intel.com" , "kernel-team@meta.com" , "david@kernel.org" , "akpm@linux-foundation.org" , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "peterx@redhat.com" , "tj@kernel.org" , "azpijr@gmail.com" , "linux-mm@kvack.org" , "hpa@zytor.com" , "tglx@kernel.org" , "peterz@infradead.org" , "rmclure@linux.ibm.com" , "bp@alien8.de" , "baolin.wang@linux.alibaba.com" , "x86@kernel.org" Subject: Re: [PATCH] x86/mm: Define the zapped-entry checks only with CONFIG_DEBUG_VM Message-ID: References: <20261102144001.342837-1-kas@kernel.org> 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 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Nov 03, 2026 at 03:50:04PM +0000, Edgecombe, Rick P wrote: > On Tue, 2026-11-03 at 10:13 +0000, Kiryl Shutsemau wrote: > > On Mon, Nov 02, 2026 at 01:12:47PM -0800, Dave Hansen wrote: > > > Or, heck, I'm not that attached to these checks. Let's just kill them. > > > > Works for me. x86 is the only architecture with them, although arm64 and > > riscv have shadow stacks too, and the x86 helpers already keep > > Write=0,Dirty=1 out of other VMAs. Patch below, without the Fixes: tag. > > > > Rick, any objection? > > Eh, I guess I'm lukewarm on it. These checks only catch the case at zap time, so > it's not a huge protection that is being pulled out. I thought they were useful. > At the same time, they have never triggered. Yeah, I have not find any reports. So, we can claim that the check served its purpose to stabilize shadow stack and can be retired now :P I will post the patch separately. -- Kiryl Shutsemau / Kirill A. Shutemov