On 7/6/26 13:50, Li Zhe wrote: > On Mon, Jul 6, 2026 at 11:13:45AM +0200, [email protected] wrote: > >>> +static inline bool pagemap_resets_refcount(const struct dev_pagemap *pgmap) >>> +{ >>> + /* >>> + * MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in the free >>> + * path. The remaining ZONE_DEVICE types start from 0 here and raise >>> + * the count again when the allocator or driver hands the page out. >>> + */ >>> + switch (pgmap->type) { >>> + case MEMORY_DEVICE_FS_DAX: >>> + case MEMORY_DEVICE_PRIVATE: >>> + case MEMORY_DEVICE_COHERENT: >>> + case MEMORY_DEVICE_PCI_P2PDMA: >>> + return false; >>> + case MEMORY_DEVICE_GENERIC: >>> + return true; >>> + default: >>> + WARN_ONCE(1, "Unknown memory type!"); >>> + return true; >> >> Wouldn't the compiler warn if we would define a new type but forgot to >> update it >> here? We're using an enum, and I thought the compiler would bail out in that >> case. >> >> Or are we scared of some other garbage ending up in there? >> >> Apart from that LGTM. > > Thanks. > > I will drop the default case in v6 so a newly added enum memory_type > value is easier to catch during build review. > > I will move the WARN_ONCE() after the switch so we still keep a > runtime guard in case some invalid value ever shows up there.
If the compiler complains, we won't need the WARN_ONCE(). -- Cheers, David
