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Fri, 26 Sep 2025 09:29:54 -0700 (PDT) Date: Fri, 26 Sep 2025 09:29:54 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: Yang Shi cc: muchun.song@linux.dev, osalvador@suse.de, david@redhat.com, akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org, carl@os.amperecomputing.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: hugetlb: avoid soft lockup when mprotect with PROT_MTE In-Reply-To: <20250926162034.1785899-1-yang@os.amperecomputing.com> Message-ID: <1038c7c7-81d6-f273-6fa1-93eb7206d5ed@gentwo.org> References: <20250926162034.1785899-1-yang@os.amperecomputing.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: E296AA0016 X-Stat-Signature: ubqjpj89i41ii4xin3j8a691usezh6w6 X-Rspam-User: X-HE-Tag: 1758904195-783521 X-HE-Meta: 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 WnWUDf5d CqQqboVI2+1spID6bv8ESB8/L79wIcVHEkr/63/2TksQsLwcW4CS1Fl/lNG5QEK4a5tYvERVFDjNFBZ+UjOPeIHNVpHMh7F1fkpHcUw2tXuszwI1uIGmHsTZKubpAW5yZ1bshfEBxDzf+MrLFkBBTVAvUVANtYjeUgxjVCH5xWlwHST1XJQcdxP6qLJoC7GRpqW8wj6wEc0l043BCtw7Sp4q3Snh3weG6U3BFImHkv5I9zWf+aoF2H/KnVyKz9d7D4CGeMrrh0KvLNFMsizr0Yrclt/Ek27j8hVbvpYkygYOinZaQpEGSYirP5g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 26 Sep 2025, Yang Shi wrote: > When calling mprotect() with PROT_MTE, kernel will initialize MTE tags > for every single page in the affected area. Soft lockup was observed > when doing this for large HugeTLB memory area in our customer's workload > (~300GB memory): AFAICT this is a bug fix. The hugetlb path should be doing a cond_resched() like the base page code does. It is not MTE specific. If other processing takes a long time in the loop (setting up terabyte size mappings for hugetlb for example) then the softlockup could also be triggered on non MTE workloads. Reviewed-by: Christoph Lameter (Ampere)