Re: [PATCH] mm: skip CMA pages when they are not available

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

Hi zhaoyang.huang,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/zhaoyang-huang/mm-skip-CMA-pages-when-they-are-not-available/20230419-134421
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/1681882824-17532-1-git-send-email-zhaoyang.huang%40unisoc.com
patch subject: [PATCH] mm: skip CMA pages when they are not available
config: i386-randconfig-a012-20230417 (https://download.01.org/0day-ci/archive/20230419/202304191908.Bqx6phWT-lkp@intel.com/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/346b74f2bf2155cb8be6af66b346157c7681b9c9
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review zhaoyang-huang/mm-skip-CMA-pages-when-they-are-not-available/20230419-134421
        git checkout 346b74f2bf2155cb8be6af66b346157c7681b9c9
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304191908.Bqx6phWT-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/vmscan.c:2317:40: error: use of undeclared identifier 'MIGRATE_CMA'; did you mean 'MIGRATE_SYNC'?
                           (get_pageblock_migratetype(page) == MIGRATE_CMA && !cma_cap)) {
                                                               ^~~~~~~~~~~
                                                               MIGRATE_SYNC
   include/linux/migrate_mode.h:18:2: note: 'MIGRATE_SYNC' declared here
           MIGRATE_SYNC,
           ^
   1 error generated.


vim +2317 mm/vmscan.c

  2261	
  2262	/*
  2263	 * Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
  2264	 *
  2265	 * lruvec->lru_lock is heavily contended.  Some of the functions that
  2266	 * shrink the lists perform better by taking out a batch of pages
  2267	 * and working on them outside the LRU lock.
  2268	 *
  2269	 * For pagecache intensive workloads, this function is the hottest
  2270	 * spot in the kernel (apart from copy_*_user functions).
  2271	 *
  2272	 * Lru_lock must be held before calling this function.
  2273	 *
  2274	 * @nr_to_scan:	The number of eligible pages to look through on the list.
  2275	 * @lruvec:	The LRU vector to pull pages from.
  2276	 * @dst:	The temp list to put pages on to.
  2277	 * @nr_scanned:	The number of pages that were scanned.
  2278	 * @sc:		The scan_control struct for this reclaim session
  2279	 * @lru:	LRU list id for isolating
  2280	 *
  2281	 * returns how many pages were moved onto *@dst.
  2282	 */
  2283	static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
  2284			struct lruvec *lruvec, struct list_head *dst,
  2285			unsigned long *nr_scanned, struct scan_control *sc,
  2286			enum lru_list lru)
  2287	{
  2288		struct list_head *src = &lruvec->lists[lru];
  2289		unsigned long nr_taken = 0;
  2290		unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 };
  2291		unsigned long nr_skipped[MAX_NR_ZONES] = { 0, };
  2292		unsigned long skipped = 0;
  2293		unsigned long scan, total_scan, nr_pages;
  2294		bool cma_cap = true;
  2295		struct page *page;
  2296		LIST_HEAD(folios_skipped);
  2297	
  2298		total_scan = 0;
  2299		scan = 0;
  2300		if ((IS_ENABLED(CONFIG_CMA)) && !current_is_kswapd()
  2301			&& (gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE))
  2302			cma_cap = false;
  2303	
  2304		while (scan < nr_to_scan && !list_empty(src)) {
  2305			struct list_head *move_to = src;
  2306			struct folio *folio;
  2307	
  2308			folio = lru_to_folio(src);
  2309			prefetchw_prev_lru_folio(folio, src, flags);
  2310	
  2311			nr_pages = folio_nr_pages(folio);
  2312			total_scan += nr_pages;
  2313	
  2314			page = &folio->page;
  2315	
  2316			if (folio_zonenum(folio) > sc->reclaim_idx ||
> 2317				(get_pageblock_migratetype(page) == MIGRATE_CMA && !cma_cap)) {
  2318				nr_skipped[folio_zonenum(folio)] += nr_pages;
  2319				move_to = &folios_skipped;
  2320				goto move;
  2321			}
  2322	
  2323			/*
  2324			 * Do not count skipped folios because that makes the function
  2325			 * return with no isolated folios if the LRU mostly contains
  2326			 * ineligible folios.  This causes the VM to not reclaim any
  2327			 * folios, triggering a premature OOM.
  2328			 * Account all pages in a folio.
  2329			 */
  2330			scan += nr_pages;
  2331	
  2332			if (!folio_test_lru(folio))
  2333				goto move;
  2334			if (!sc->may_unmap && folio_mapped(folio))
  2335				goto move;
  2336	
  2337			/*
  2338			 * Be careful not to clear the lru flag until after we're
  2339			 * sure the folio is not being freed elsewhere -- the
  2340			 * folio release code relies on it.
  2341			 */
  2342			if (unlikely(!folio_try_get(folio)))
  2343				goto move;
  2344	
  2345			if (!folio_test_clear_lru(folio)) {
  2346				/* Another thread is already isolating this folio */
  2347				folio_put(folio);
  2348				goto move;
  2349			}
  2350	
  2351			nr_taken += nr_pages;
  2352			nr_zone_taken[folio_zonenum(folio)] += nr_pages;
  2353			move_to = dst;
  2354	move:
  2355			list_move(&folio->lru, move_to);
  2356		}
  2357	
  2358		/*
  2359		 * Splice any skipped folios to the start of the LRU list. Note that
  2360		 * this disrupts the LRU order when reclaiming for lower zones but
  2361		 * we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX
  2362		 * scanning would soon rescan the same folios to skip and waste lots
  2363		 * of cpu cycles.
  2364		 */
  2365		if (!list_empty(&folios_skipped)) {
  2366			int zid;
  2367	
  2368			list_splice(&folios_skipped, src);
  2369			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
  2370				if (!nr_skipped[zid])
  2371					continue;
  2372	
  2373				__count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
  2374				skipped += nr_skipped[zid];
  2375			}
  2376		}
  2377		*nr_scanned = total_scan;
  2378		trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
  2379					    total_scan, skipped, nr_taken,
  2380					    sc->may_unmap ? 0 : ISOLATE_UNMAPPED, lru);
  2381		update_lru_sizes(lruvec, lru, nr_zone_taken);
  2382		return nr_taken;
  2383	}
  2384	

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