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Message-ID: <202304201725.pa3nMNWa-lkp@intel.com>
Date: Thu, 20 Apr 2023 17:44:58 +0800
From: kernel test robot <lkp@...el.com>
To: "zhaoyang.huang" <zhaoyang.huang@...soc.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
Zhaoyang Huang <huangzhaoyang@...il.com>, ke.wang@...soc.com
Cc: oe-kbuild-all@...ts.linux.dev,
Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [PATCHv2] mm: skip CMA pages when they are not available
Hi zhaoyang.huang,
kernel test robot noticed the following build warnings:
[auto build test WARNING 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/20230420-163443
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/1681979577-11360-1-git-send-email-zhaoyang.huang%40unisoc.com
patch subject: [PATCHv2] mm: skip CMA pages when they are not available
config: powerpc-allnoconfig (https://download.01.org/0day-ci/archive/20230420/202304201725.pa3nMNWa-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 12.1.0
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/intel-lab-lkp/linux/commit/2227e95350088b79da6d6b9e6c95a67474593852
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/20230420-163443
git checkout 2227e95350088b79da6d6b9e6c95a67474593852
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304201725.pa3nMNWa-lkp@intel.com/
All warnings (new ones prefixed by >>):
mm/vmscan.c: In function 'isolate_lru_folios':
>> mm/vmscan.c:2295:22: warning: variable 'page' set but not used [-Wunused-but-set-variable]
2295 | struct page *page;
| ^~~~
>> mm/vmscan.c:2294:14: warning: variable 'cma_cap' set but not used [-Wunused-but-set-variable]
2294 | bool cma_cap = true;
| ^~~~~~~
vim +/page +2295 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 *@....
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 #ifdef CONFIG_CMA
2318 || (get_pageblock_migratetype(page) == MIGRATE_CMA && !cma_cap)
2319 #endif
2320 ) {
2321 nr_skipped[folio_zonenum(folio)] += nr_pages;
2322 move_to = &folios_skipped;
2323 goto move;
2324 }
2325 /*
2326 * Do not count skipped folios because that makes the function
2327 * return with no isolated folios if the LRU mostly contains
2328 * ineligible folios. This causes the VM to not reclaim any
2329 * folios, triggering a premature OOM.
2330 * Account all pages in a folio.
2331 */
2332 scan += nr_pages;
2333
2334 if (!folio_test_lru(folio))
2335 goto move;
2336 if (!sc->may_unmap && folio_mapped(folio))
2337 goto move;
2338
2339 /*
2340 * Be careful not to clear the lru flag until after we're
2341 * sure the folio is not being freed elsewhere -- the
2342 * folio release code relies on it.
2343 */
2344 if (unlikely(!folio_try_get(folio)))
2345 goto move;
2346
2347 if (!folio_test_clear_lru(folio)) {
2348 /* Another thread is already isolating this folio */
2349 folio_put(folio);
2350 goto move;
2351 }
2352
2353 nr_taken += nr_pages;
2354 nr_zone_taken[folio_zonenum(folio)] += nr_pages;
2355 move_to = dst;
2356 move:
2357 list_move(&folio->lru, move_to);
2358 }
2359
2360 /*
2361 * Splice any skipped folios to the start of the LRU list. Note that
2362 * this disrupts the LRU order when reclaiming for lower zones but
2363 * we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX
2364 * scanning would soon rescan the same folios to skip and waste lots
2365 * of cpu cycles.
2366 */
2367 if (!list_empty(&folios_skipped)) {
2368 int zid;
2369
2370 list_splice(&folios_skipped, src);
2371 for (zid = 0; zid < MAX_NR_ZONES; zid++) {
2372 if (!nr_skipped[zid])
2373 continue;
2374
2375 __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
2376 skipped += nr_skipped[zid];
2377 }
2378 }
2379 *nr_scanned = total_scan;
2380 trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
2381 total_scan, skipped, nr_taken,
2382 sc->may_unmap ? 0 : ISOLATE_UNMAPPED, lru);
2383 update_lru_sizes(lruvec, lru, nr_zone_taken);
2384 return nr_taken;
2385 }
2386
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
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