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For that read to > be safe, two things are needed: What driver does this? iommu_report_device_fault() has to be called in a sleepable context - usually a threaded IRQ handler. So mutex is no problem. This seems like Sashiko slop - iommu_group does not change while a driver is attached and a driver is not permitted to do any "fault handling" after it has detached, it must flush and synchronize its IRQ if it is using this from a hard IRQ for some bad reason. You need to be alot more critical about the noise that Sashiko generates, alot is useful, alot is not. It is a not a tool you want to have 0 reports, complaining about hallucinations is expected. > +#define dev_iommu_group_rcu(dev) \ > + (*((struct iommu_group __rcu __force **)&(dev)->iommu_group)) Don't do things like this. Jason