Hello,
I don't know if there is a bug here, but it could e worth checking on. If
the loop on line 1481 is executed, page will not be NULL at the out label
on line 1560. Instead it will have a dummy value. Perhaps the value of
result keeps the if at the out label from being taken.
julia
---------- Forwarded message ----------
Date: Tue, 9 May 2017 23:27:43 +0800
From: kbuild test robot <fengguang.wu@xxxxxxxxx>
To: kbuild@xxxxxx
Cc: Julia Lawall <julia.lawall@xxxxxxx>
Subject: Re: [PATCH v2] mm: fix the memory leak after collapsing the huge page
fails
Hi zhong,
[auto build test WARNING on mmotm/master]
[also build test WARNING on v4.11 next-20170509]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/zhongjiang/mm-fix-the-memory-leak-after-collapsing-the-huge-page-fails/20170509-193011
base: git://git.cmpxchg.org/linux-mmotm.git master
:::::: branch date: 4 hours ago
:::::: commit date: 4 hours ago
>> mm/khugepaged.c:1560:5-9: ERROR: invalid reference to the index variable of the iterator on line 1481
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout a5318ea654d5b764d6e06c6cfbfc21e44ce56e2b
vim +1560 mm/khugepaged.c
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1475 struct zone *zone = page_zone(new_page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1476
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1477 /*
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1478 * Replacing old pages with new one has succeed, now we need to
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1479 * copy the content and free old pages.
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1480 */
f3f0e1d2 Kirill A. Shutemov 2016-07-26 @1481 list_for_each_entry_safe(page, tmp, &pagelist, lru) {
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1482 copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1483 page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1484 list_del(&page->lru);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1485 unlock_page(page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1486 page_ref_unfreeze(page, 1);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1487 page->mapping = NULL;
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1488 ClearPageActive(page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1489 ClearPageUnevictable(page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1490 put_page(page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1491 }
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1492
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1493 local_irq_save(flags);
11fb9989 Mel Gorman 2016-07-28 1494 __inc_node_page_state(new_page, NR_SHMEM_THPS);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1495 if (nr_none) {
11fb9989 Mel Gorman 2016-07-28 1496 __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
11fb9989 Mel Gorman 2016-07-28 1497 __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1498 }
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1499 local_irq_restore(flags);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1500
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1501 /*
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1502 * Remove pte page tables, so we can re-faulti
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1503 * the page as huge.
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1504 */
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1505 retract_page_tables(mapping, start);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1506
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1507 /* Everything is ready, let's unfreeze the new_page */
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1508 set_page_dirty(new_page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1509 SetPageUptodate(new_page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1510 page_ref_unfreeze(new_page, HPAGE_PMD_NR);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1511 mem_cgroup_commit_charge(new_page, memcg, false, true);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1512 lru_cache_add_anon(new_page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1513 unlock_page(new_page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1514
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1515 *hpage = NULL;
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1516 } else {
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1517 /* Something went wrong: rollback changes to the radix-tree */
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1518 shmem_uncharge(mapping->host, nr_none);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1519 spin_lock_irq(&mapping->tree_lock);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1520 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter,
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1521 start) {
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1522 if (iter.index >= end)
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1523 break;
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1524 page = list_first_entry_or_null(&pagelist,
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1525 struct page, lru);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1526 if (!page || iter.index < page->index) {
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1527 if (!nr_none)
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1528 break;
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1529 nr_none--;
59749e6c Johannes Weiner 2016-12-12 1530 /* Put holes back where they were */
59749e6c Johannes Weiner 2016-12-12 1531 radix_tree_delete(&mapping->page_tree,
59749e6c Johannes Weiner 2016-12-12 1532 iter.index);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1533 continue;
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1534 }
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1535
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1536 VM_BUG_ON_PAGE(page->index != iter.index, page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1537
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1538 /* Unfreeze the page. */
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1539 list_del(&page->lru);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1540 page_ref_unfreeze(page, 2);
6d75f366 Johannes Weiner 2016-12-12 1541 radix_tree_replace_slot(&mapping->page_tree,
6d75f366 Johannes Weiner 2016-12-12 1542 slot, page);
148deab2 Matthew Wilcox 2016-12-14 1543 slot = radix_tree_iter_resume(slot, &iter);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1544 spin_unlock_irq(&mapping->tree_lock);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1545 putback_lru_page(page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1546 unlock_page(page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1547 spin_lock_irq(&mapping->tree_lock);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1548 }
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1549 VM_BUG_ON(nr_none);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1550 spin_unlock_irq(&mapping->tree_lock);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1551
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1552 /* Unfreeze new_page, caller would take care about freeing it */
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1553 page_ref_unfreeze(new_page, 1);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1554 mem_cgroup_cancel_charge(new_page, memcg, true);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1555 unlock_page(new_page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1556 new_page->mapping = NULL;
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1557 }
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1558 out:
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1559 VM_BUG_ON(!list_empty(&pagelist));
a5318ea6 zhong jiang 2017-05-09 @1560 if (page != NULL && result != SCAN_SUCCEED)
a5318ea6 zhong jiang 2017-05-09 1561 put_page(new_page);
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1562 /* TODO: tracepoints */
f3f0e1d2 Kirill A. Shutemov 2016-07-26 1563 }
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