Question about mm/compaction.c/acct_isolated: computing nr_anon, nr_file

Wang Sheng-Hui
2011-11-25T05:43:00Z

Why does it double the number in line 233/234?

222/* Update the number of anon and file isolated pages in the zone */
223static void acct_isolated(struct zone *zone, struct compact_control *cc)
224{
225 struct page *page;
226 unsigned int count[NR_LRU_LISTS] = { 0, };
227
228 list_for_each_entry(page, &cc->migratepages, lru) {
229 int lru = page_lru_base_type(page);
230 count[lru]++;
231 }
232
233 cc->nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
234 cc->nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
235 __mod_zone_page_state(zone, NR_ISOLATED_ANON, cc->nr_anon);
236 __mod_zone_page_state(zone, NR_ISOLATED_FILE, cc->nr_file);
237}

thanks,