Re: [PATCH 11/21] KVM: x86/MMU: Cleanup shrinker interface with Shadow MMU

From: kernel test robot
Date: Sat Feb 04 2023 - 14:11:06 EST


Hi Ben,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on 7cb79f433e75b05d1635aefaa851cfcd1cb7dc4f]

url: https://github.com/intel-lab-lkp/linux/commits/Ben-Gardon/KVM-x86-mmu-Rename-slot-rmap-walkers-to-add-clarity-and-clean-up-code/20230203-023259
base: 7cb79f433e75b05d1635aefaa851cfcd1cb7dc4f
patch link: https://lore.kernel.org/r/20230202182809.1929122-12-bgardon%40google.com
patch subject: [PATCH 11/21] KVM: x86/MMU: Cleanup shrinker interface with Shadow MMU
config: x86_64-randconfig-a014 (https://download.01.org/0day-ci/archive/20230205/202302050303.kLjMucYK-lkp@xxxxxxxxx/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/c1170de906dfe1ee64da0066e7c28d35e716ed18
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Ben-Gardon/KVM-x86-mmu-Rename-slot-rmap-walkers-to-add-clarity-and-clean-up-code/20230203-023259
git checkout c1170de906dfe1ee64da0066e7c28d35e716ed18
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/kvm/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> arch/x86/kvm/mmu/mmu.c:3148:15: warning: no previous prototype for function 'mmu_shrink_scan' [-Wmissing-prototypes]
unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
^
arch/x86/kvm/mmu/mmu.c:3148:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
^
static
1 warning generated.


vim +/mmu_shrink_scan +3148 arch/x86/kvm/mmu/mmu.c

3147
> 3148 unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
3149 {
3150 struct kvm *kvm;
3151 int nr_to_scan = sc->nr_to_scan;
3152 unsigned long freed = 0;
3153
3154 mutex_lock(&kvm_lock);
3155
3156 list_for_each_entry(kvm, &vm_list, vm_list) {
3157 /*
3158 * Never scan more than sc->nr_to_scan VM instances.
3159 * Will not hit this condition practically since we do not try
3160 * to shrink more than one VM and it is very unlikely to see
3161 * !n_used_mmu_pages so many times.
3162 */
3163 if (!nr_to_scan--)
3164 break;
3165
3166 /*
3167 * n_used_mmu_pages is accessed without holding kvm->mmu_lock
3168 * here. We may skip a VM instance errorneosly, but we do not
3169 * want to shrink a VM that only started to populate its MMU
3170 * anyway.
3171 */
3172 if (!kvm->arch.n_used_mmu_pages &&
3173 !kvm_shadow_mmu_has_zapped_obsolete_pages(kvm))
3174 continue;
3175
3176 freed = kvm_shadow_mmu_shrink_scan(kvm, sc->nr_to_scan);
3177
3178 /*
3179 * unfair on small ones
3180 * per-vm shrinkers cry out
3181 * sadness comes quickly
3182 */
3183 list_move_tail(&kvm->vm_list, &vm_list);
3184 break;
3185 }
3186
3187 mutex_unlock(&kvm_lock);
3188 return freed;
3189 }
3190

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests