Re: [RFC PATCH v4 06/14] KVM: guest_memfd: Handle final folio_put() of guestmem pages

[kernel test robot <lkp@intel.com>]

Hi Fuad,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on fac04efc5c793dccbd07e2d59af9f90b7fc0dca4]

url:    https://github.com/intel-lab-lkp/linux/commits/Fuad-Tabba/mm-Consolidate-freeing-of-typed-folios-on-final-folio_put/20241214-005109
base:   fac04efc5c793dccbd07e2d59af9f90b7fc0dca4
patch link:    https://lore.kernel.org/r/20241213164811.2006197-7-tabba%40google.com
patch subject: [RFC PATCH v4 06/14] KVM: guest_memfd: Handle final folio_put() of guestmem pages
config: i386-buildonly-randconfig-006-20241215 (https://download.01.org/0day-ci/archive/20241215/202412150235.pdU2pDm8-lkp@intel.com/config)
compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241215/202412150235.pdU2pDm8-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202412150235.pdU2pDm8-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from arch/x86/events/intel/core.c:17:
   In file included from include/linux/kvm_host.h:16:
   In file included from include/linux/mm.h:2223:
   include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     518 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
   In file included from arch/x86/events/intel/core.c:17:
>> include/linux/kvm_host.h:2620:5: warning: no previous prototype for function 'kvm_slot_gmem_register_callback' [-Wmissing-prototypes]
    2620 | int kvm_slot_gmem_register_callback(struct kvm_memory_slot *slot, gfn_t gfn)
         |     ^
   include/linux/kvm_host.h:2620:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
    2620 | int kvm_slot_gmem_register_callback(struct kvm_memory_slot *slot, gfn_t gfn)
         | ^
         | static 
   2 warnings generated.


vim +/kvm_slot_gmem_register_callback +2620 include/linux/kvm_host.h

  2566	
  2567	#ifdef CONFIG_KVM_GMEM_MAPPABLE
  2568	bool kvm_gmem_is_mappable(struct kvm *kvm, gfn_t gfn, gfn_t end);
  2569	int kvm_gmem_set_mappable(struct kvm *kvm, gfn_t start, gfn_t end);
  2570	int kvm_gmem_clear_mappable(struct kvm *kvm, gfn_t start, gfn_t end);
  2571	int kvm_slot_gmem_set_mappable(struct kvm_memory_slot *slot, gfn_t start,
  2572				       gfn_t end);
  2573	int kvm_slot_gmem_clear_mappable(struct kvm_memory_slot *slot, gfn_t start,
  2574					 gfn_t end);
  2575	bool kvm_slot_gmem_is_mappable(struct kvm_memory_slot *slot, gfn_t gfn);
  2576	bool kvm_slot_gmem_is_guest_mappable(struct kvm_memory_slot *slot, gfn_t gfn);
  2577	int kvm_slot_gmem_register_callback(struct kvm_memory_slot *slot, gfn_t gfn);
  2578	void kvm_gmem_handle_folio_put(struct folio *folio);
  2579	#else
  2580	static inline bool kvm_gmem_is_mappable(struct kvm *kvm, gfn_t gfn, gfn_t end)
  2581	{
  2582		WARN_ON_ONCE(1);
  2583		return false;
  2584	}
  2585	static inline int kvm_gmem_set_mappable(struct kvm *kvm, gfn_t start, gfn_t end)
  2586	{
  2587		WARN_ON_ONCE(1);
  2588		return -EINVAL;
  2589	}
  2590	static inline int kvm_gmem_clear_mappable(struct kvm *kvm, gfn_t start,
  2591						  gfn_t end)
  2592	{
  2593		WARN_ON_ONCE(1);
  2594		return -EINVAL;
  2595	}
  2596	static inline int kvm_slot_gmem_set_mappable(struct kvm_memory_slot *slot,
  2597						     gfn_t start, gfn_t end)
  2598	{
  2599		WARN_ON_ONCE(1);
  2600		return -EINVAL;
  2601	}
  2602	static inline int kvm_slot_gmem_clear_mappable(struct kvm_memory_slot *slot,
  2603						       gfn_t start, gfn_t end)
  2604	{
  2605		WARN_ON_ONCE(1);
  2606		return -EINVAL;
  2607	}
  2608	static inline bool kvm_slot_gmem_is_mappable(struct kvm_memory_slot *slot,
  2609						     gfn_t gfn)
  2610	{
  2611		WARN_ON_ONCE(1);
  2612		return false;
  2613	}
  2614	static inline bool kvm_slot_gmem_is_guest_mappable(struct kvm_memory_slot *slot,
  2615							   gfn_t gfn)
  2616	{
  2617		WARN_ON_ONCE(1);
  2618		return false;
  2619	}
> 2620	int kvm_slot_gmem_register_callback(struct kvm_memory_slot *slot, gfn_t gfn)
  2621	{
  2622		WARN_ON_ONCE(1);
  2623		return -EINVAL;
  2624	}
  2625	static inline void kvm_gmem_handle_folio_put(struct folio *folio)
  2626	{
  2627		WARN_ON_ONCE(1);
  2628	}
  2629	#endif /* CONFIG_KVM_GMEM_MAPPABLE */
  2630	

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