Re: [PATCH] mm: hugetlb: avoid soft lockup when mprotect with PROT_MTE

Christoph Lameter (Ampere)
2025-09-26T16:29:58Z

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) <cl@gentwo.org>