Hello Matthew Wilcox,
The patch d31429cb560d: "mm: Convert collapse_shmem to XArray" from
Dec 4, 2017, leads to the following static checker warning:
mm/khugepaged.c:1435 collapse_shmem()
error: double unlock 'irq:'
mm/khugepaged.c
1398 xas_unlock_irq(&xas);
1399
1400 if (isolate_lru_page(page)) {
1401 result = SCAN_DEL_PAGE_LRU;
1402 goto out_isolate_failed;
1403 }
1404
1405 if (page_mapped(page))
1406 unmap_mapping_pages(mapping, index, 1, false);
1407
1408 xas_lock(&xas);
^^^^^^^^^^^^^^
This used to disable IRQs.
1409 xas_set(&xas, index);
1410
1411 VM_BUG_ON_PAGE(page != xas_load(&xas), page);
1412 VM_BUG_ON_PAGE(page_mapped(page), page);
1413
1414 /*
1415 * The page is expected to have page_count() == 3:
1416 * - we hold a pin on it;
1417 * - one reference from page cache;
1418 * - one from isolate_lru_page;
1419 */
1420 if (!page_ref_freeze(page, 3)) {
1421 result = SCAN_PAGE_COUNT;
1422 goto out_lru;
1423 }
1424
1425 /*
1426 * Add the page to the list to be able to undo the collapse if
1427 * something go wrong.
1428 */
1429 list_add_tail(&page->lru, &pagelist);
1430
1431 /* Finally, replace with the new page. */
1432 xas_store(&xas, new_page + (index % HPAGE_PMD_NR));
1433 continue;
1434 out_lru:
1435 xas_unlock_irq(&xas);
^^^^^^^^^^^^^^^^^^^
So I guess we should change this to xas_unlock(&xas);?
1436 putback_lru_page(page);
1437 out_isolate_failed:
1438 unlock_page(page);
1439 put_page(page);
1440 goto xa_unlocked;
1441 out_unlock:
regards,
dan carpenter
