Hi John, First bad commit (maybe != root cause): tree: https://android.googlesource.com/kernel/common android12-5.4 head: 82c67a98c7494b4e71dcbea03335509e9ccecfa5 commit: 44008f99d9ca0793e2562967e1da01fa74ee4a41 [4/9] ANDROID: dma-buf: system_heap: Add pagepool support to system heap config: i386-randconfig-s001-20210812 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.3-348-gf0e6938b-dirty git remote add android-common https://android.googlesource.com/kernel/common git fetch --no-tags android-common android12-5.4 git checkout 44008f99d9ca0793e2562967e1da01fa74ee4a41 # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=i386 SHELL=/bin/bash drivers/dma-buf/heaps/ kernel/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) drivers/dma-buf/heaps/page_pool.c:243:5: sparse: sparse: symbol 'dmabuf_page_pool_init_shrinker' was not declared. Should it be static? vim +/pool_shrinker +236 drivers/dma-buf/heaps/page_pool.c bd4db96bfc247a John Stultz 2020-10-02 235 bd4db96bfc247a John Stultz 2020-10-02 @236 struct shrinker pool_shrinker = { bd4db96bfc247a John Stultz 2020-10-02 237 .count_objects = dmabuf_page_pool_shrink_count, bd4db96bfc247a John Stultz 2020-10-02 238 .scan_objects = dmabuf_page_pool_shrink_scan, bd4db96bfc247a John Stultz 2020-10-02 239 .seeks = DEFAULT_SEEKS, bd4db96bfc247a John Stultz 2020-10-02 240 .batch = 0, bd4db96bfc247a John Stultz 2020-10-02 241 }; bd4db96bfc247a John Stultz 2020-10-02 242 :::::: The code at line 236 was first introduced by commit :::::: bd4db96bfc247afdaf7a4cfde85fd8147522f3e6 ANDROID: dma-buf: heaps: Add a shrinker controlled page pool :::::: TO: John Stultz <john.stultz(a)linaro.org&gt; :::::: CC: John Stultz <john.stultz(a)linaro.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org