Hi, Thank you for the patch! Yet something to improve: [auto build test ERROR on hnaz-mm/master] url: https://github.com/intel-lab-lkp/linux/commits/cgel-zte-gmail-com/mm-vmstat-add-events-for-ksm-cow/20220330-162859 base: https://github.com/hnaz/linux-mm master config: hexagon-buildonly-randconfig-r006-20220330 (https://download.01.org/0day-ci/archive/20220330/202203302113.QzkSLwzk-lkp@xxxxxxxxx/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 0f6d9501cf49ce02937099350d08f20c4af86f3d) 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/48bd13bff24d30af750dd9429638a2563b758611 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review cgel-zte-gmail-com/mm-vmstat-add-events-for-ksm-cow/20220330-162859 git checkout 48bd13bff24d30af750dd9429638a2563b758611 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All errors (new ones prefixed by >>): >> mm/memory.c:3336:18: error: use of undeclared identifier 'COW_KSM' count_vm_event(COW_KSM); ^ 1 error generated. vim +/COW_KSM +3336 mm/memory.c 3229 3230 /* 3231 * This routine handles present pages, when users try to write 3232 * to a shared page. It is done by copying the page to a new address 3233 * and decrementing the shared-page counter for the old page. 3234 * 3235 * Note that this routine assumes that the protection checks have been 3236 * done by the caller (the low-level page fault routine in most cases). 3237 * Thus we can safely just mark it writable once we've done any necessary 3238 * COW. 3239 * 3240 * We also mark the page dirty at this point even though the page will 3241 * change only once the write actually happens. This avoids a few races, 3242 * and potentially makes it more efficient. 3243 * 3244 * We enter with non-exclusive mmap_lock (to exclude vma changes, 3245 * but allow concurrent faults), with pte both mapped and locked. 3246 * We return with mmap_lock still held, but pte unmapped and unlocked. 3247 */ 3248 static vm_fault_t do_wp_page(struct vm_fault *vmf) 3249 __releases(vmf->ptl) 3250 { 3251 struct vm_area_struct *vma = vmf->vma; 3252 3253 if (userfaultfd_pte_wp(vma, *vmf->pte)) { 3254 pte_unmap_unlock(vmf->pte, vmf->ptl); 3255 return handle_userfault(vmf, VM_UFFD_WP); 3256 } 3257 3258 /* 3259 * Userfaultfd write-protect can defer flushes. Ensure the TLB 3260 * is flushed in this case before copying. 3261 */ 3262 if (unlikely(userfaultfd_wp(vmf->vma) && 3263 mm_tlb_flush_pending(vmf->vma->vm_mm))) 3264 flush_tlb_page(vmf->vma, vmf->address); 3265 3266 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte); 3267 if (!vmf->page) { 3268 /* 3269 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a 3270 * VM_PFNMAP VMA. 3271 * 3272 * We should not cow pages in a shared writeable mapping. 3273 * Just mark the pages writable and/or call ops->pfn_mkwrite. 3274 */ 3275 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 3276 (VM_WRITE|VM_SHARED)) 3277 return wp_pfn_shared(vmf); 3278 3279 pte_unmap_unlock(vmf->pte, vmf->ptl); 3280 return wp_page_copy(vmf); 3281 } 3282 3283 /* 3284 * Take out anonymous pages first, anonymous shared vmas are 3285 * not dirty accountable. 3286 */ 3287 if (PageAnon(vmf->page)) { 3288 struct page *page = vmf->page; 3289 3290 /* 3291 * We have to verify under page lock: these early checks are 3292 * just an optimization to avoid locking the page and freeing 3293 * the swapcache if there is little hope that we can reuse. 3294 * 3295 * PageKsm() doesn't necessarily raise the page refcount. 3296 */ 3297 if (PageKsm(page) || page_count(page) > 3) 3298 goto copy; 3299 if (!PageLRU(page)) 3300 /* 3301 * Note: We cannot easily detect+handle references from 3302 * remote LRU pagevecs or references to PageLRU() pages. 3303 */ 3304 lru_add_drain(); 3305 if (page_count(page) > 1 + PageSwapCache(page)) 3306 goto copy; 3307 if (!trylock_page(page)) 3308 goto copy; 3309 if (PageSwapCache(page)) 3310 try_to_free_swap(page); 3311 if (PageKsm(page) || page_count(page) != 1) { 3312 unlock_page(page); 3313 goto copy; 3314 } 3315 /* 3316 * Ok, we've got the only page reference from our mapping 3317 * and the page is locked, it's dark out, and we're wearing 3318 * sunglasses. Hit it. 3319 */ 3320 unlock_page(page); 3321 wp_page_reuse(vmf); 3322 return VM_FAULT_WRITE; 3323 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 3324 (VM_WRITE|VM_SHARED))) { 3325 return wp_page_shared(vmf); 3326 } 3327 copy: 3328 /* 3329 * Ok, we need to copy. Oh, well.. 3330 */ 3331 get_page(vmf->page); 3332 3333 pte_unmap_unlock(vmf->pte, vmf->ptl); 3334 #ifdef CONFIG_KSM 3335 if (PageKsm(vmf->page)) > 3336 count_vm_event(COW_KSM); 3337 #endif 3338 return wp_page_copy(vmf); 3339 } 3340 -- 0-DAY CI Kernel Test Service https://01.org/lkp
