Hi, Thank you for the patch! Yet something to improve: [auto build test ERROR on hnaz-mm/master] url: https://github.com/0day-ci/linux/commits/cgel-zte-gmail-com/mm-vmstat-add-events-for-ksm-cow/20220323-111932 base: https://github.com/hnaz/linux-mm master config: nios2-defconfig (https://download.01.org/0day-ci/archive/20220323/202203231454.DszZMI5Y-lkp@xxxxxxxxx/config) compiler: nios2-linux-gcc (GCC) 11.2.0 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/0day-ci/linux/commit/cc1a5f6c95b38b1bebb673c7fe3a2b64e2362acc git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review cgel-zte-gmail-com/mm-vmstat-add-events-for-ksm-cow/20220323-111932 git checkout cc1a5f6c95b38b1bebb673c7fe3a2b64e2362acc # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=nios2 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: In function 'do_wp_page': >> mm/memory.c:3341:40: error: 'KSM_COW_FAIL' undeclared (first use in this function) 3341 | count_vm_event(KSM_COW_FAIL); | ^~~~~~~~~~~~ mm/memory.c:3341:40: note: each undeclared identifier is reported only once for each function it appears in >> mm/memory.c:3343:40: error: 'KSM_COW_SUCCESS' undeclared (first use in this function) 3343 | count_vm_event(KSM_COW_SUCCESS); | ^~~~~~~~~~~~~~~ vim +/KSM_COW_FAIL +3341 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 vm_fault_t ret = 0; 3253 bool ksm = 0; 3254 3255 if (userfaultfd_pte_wp(vma, *vmf->pte)) { 3256 pte_unmap_unlock(vmf->pte, vmf->ptl); 3257 return handle_userfault(vmf, VM_UFFD_WP); 3258 } 3259 3260 /* 3261 * Userfaultfd write-protect can defer flushes. Ensure the TLB 3262 * is flushed in this case before copying. 3263 */ 3264 if (unlikely(userfaultfd_wp(vmf->vma) && 3265 mm_tlb_flush_pending(vmf->vma->vm_mm))) 3266 flush_tlb_page(vmf->vma, vmf->address); 3267 3268 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte); 3269 if (!vmf->page) { 3270 /* 3271 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a 3272 * VM_PFNMAP VMA. 3273 * 3274 * We should not cow pages in a shared writeable mapping. 3275 * Just mark the pages writable and/or call ops->pfn_mkwrite. 3276 */ 3277 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 3278 (VM_WRITE|VM_SHARED)) 3279 return wp_pfn_shared(vmf); 3280 3281 pte_unmap_unlock(vmf->pte, vmf->ptl); 3282 return wp_page_copy(vmf); 3283 } 3284 3285 /* 3286 * Take out anonymous pages first, anonymous shared vmas are 3287 * not dirty accountable. 3288 */ 3289 if (PageAnon(vmf->page)) { 3290 struct page *page = vmf->page; 3291 ksm = PageKsm(page); 3292 3293 /* 3294 * We have to verify under page lock: these early checks are 3295 * just an optimization to avoid locking the page and freeing 3296 * the swapcache if there is little hope that we can reuse. 3297 * 3298 * PageKsm() doesn't necessarily raise the page refcount. 3299 */ 3300 if (ksm || page_count(page) > 3) 3301 goto copy; 3302 if (!PageLRU(page)) 3303 /* 3304 * Note: We cannot easily detect+handle references from 3305 * remote LRU pagevecs or references to PageLRU() pages. 3306 */ 3307 lru_add_drain(); 3308 if (page_count(page) > 1 + PageSwapCache(page)) 3309 goto copy; 3310 if (!trylock_page(page)) 3311 goto copy; 3312 if (PageSwapCache(page)) 3313 try_to_free_swap(page); 3314 if (ksm || page_count(page) != 1) { 3315 unlock_page(page); 3316 goto copy; 3317 } 3318 /* 3319 * Ok, we've got the only page reference from our mapping 3320 * and the page is locked, it's dark out, and we're wearing 3321 * sunglasses. Hit it. 3322 */ 3323 unlock_page(page); 3324 wp_page_reuse(vmf); 3325 return VM_FAULT_WRITE; 3326 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 3327 (VM_WRITE|VM_SHARED))) { 3328 return wp_page_shared(vmf); 3329 } 3330 copy: 3331 /* 3332 * Ok, we need to copy. Oh, well.. 3333 */ 3334 get_page(vmf->page); 3335 3336 pte_unmap_unlock(vmf->pte, vmf->ptl); 3337 ret = wp_page_copy(vmf); 3338 3339 if (ksm) { 3340 if (unlikely(ret & VM_FAULT_ERROR)) > 3341 count_vm_event(KSM_COW_FAIL); 3342 else > 3343 count_vm_event(KSM_COW_SUCCESS); 3344 } 3345 3346 return ret; 3347 } 3348 -- 0-DAY CI Kernel Test Service https://01.org/lkp
