Messages in this thread | | | Date | Tue, 19 Jul 2022 08:06:02 +0800 | From | Lu Baolu <> | Subject | Re: [PATCH v3 01/15] iommu/vt-d: Handle race between registration and device probe |
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Hi Robin,
On 2022/7/15 20:37, Robin Murphy wrote: >> In fact the rmrr list in the Intel IOMMU driver is always static after >> parsing the ACPI/DMAR tables. There's no need to protect it with a lock. >> Hence we can safely remove below down/up_read(). > > IIRC that leads to RCU warnings via for_each_dev_scope(), though. I did > try replacing this down_read() with rcu_read_lock(), but then it doesn't > like the GFP_KERNEL allocation in iommu_alloc_resv_region(), and that's > where I gave up :) > > I'm mostly left wondering whether the dmar_drhd_units list really needs > to be RCU protected at all, as that seems to be the root of most of the > problems here.
I just posted a fix patch here:
https://lore.kernel.org/linux-iommu/20220718235325.3952426-1-baolu.lu@linux.intel.com/
It can remove the recursive locking and RCU warnings. Can you please take a look at it?
Best regards, baolu
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