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>>>> >>>> + if (folio_is_device_private(release)) >>>> + percpu_ref_get_many(&release->pgmap->ref, >>>> + (1 << new_order) - 1); >>> >>> pgmap refcount should not be modified here, count should remain the same after the split also > > Agreed. > >>> >>> >> >> Good point, let me revisit the accounting > > Yes, hopefully we can just delete it. > >> For this patch series, the tests did not catch it since new ref's evaluate to 0 > > You may not notice bad accounting here unless you unload the kernel module, > which can hang during memunmap() pages waiting for the refcount to go to zero. > The tests do have an eviction test, which tests that all pages can indeed be evicted and I do unload/reload the driver Balbir Singh