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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-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 9D43718000A X-Stat-Signature: kbgsgfupxqgw8xdujqaq8i4dszdf4j33 X-Rspam-User: X-HE-Tag: 1793879758-244365 X-HE-Meta: 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 DMaFMupn tYzMTVzWbRMdP+1w2w1VRwUIfGwWieacNe8oHgBlC2m+2OQ4t/wGMHC2Q6xCs8ch5IaWuEU0q6x+UREaDWWEXaf6ahUCHrI3fHcoAGfH8/KjaOHsBv5tEqQ4ez5HsSyrbpKTa3yfaYSqe5nPHicbohxPx6IE/EFSRsFT7pt8S/+ZgK4juzXYx3oWWiMR1l7dJB8WfqWCCC2VxUloT1TYNd8EMklyeES0KYTJWxUCycLzP9ADFOIrLM5O8hmCFn231uhHxtc1UZfqMq5WIuziY6DHJubiwVWBSUZwDf0lwSneuJfuDe/nQhKRhdpeBkbyU2rRDQr7eaDD8KYOFPfXULso2rhn1U9G60n5DQjqGKJyGWA0cmWkZQCIx8XSaVBBspvt9Jv50V4Hs+jwDADmsa8I1zjfB+PCvdQQnQmyVNoPBW7qoLXcDgb3GXPOj2LIHvfqXEHRD3nxn5aqIqKQqa6We7C9a62rsEUOp Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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