* [akpm-mm:mm-unstable 201/281] mm/rmap.c:1635:14: warning: variable 'pmd_mapped' set but not used
@ 2024-06-14 8:37 kernel test robot
2024-06-14 8:59 ` Lance Yang
0 siblings, 1 reply; 2+ messages in thread
From: kernel test robot @ 2024-06-14 8:37 UTC (permalink / raw)
To: Lance Yang; +Cc: oe-kbuild-all, Andrew Morton, Linux Memory Management List
tree: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
head: 8d0a686ea94347949eb0b689bb2a7c6028c0fa28
commit: fa687ca2801a5b5ec92912abc362507242fd5cbc [201/281] mm-vmscan-avoid-split-lazyfree-thp-during-shrink_folio_list-fix
config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240614/202406141650.B5cBNrbw-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240614/202406141650.B5cBNrbw-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202406141650.B5cBNrbw-lkp@intel.com/
All warnings (new ones prefixed by >>):
mm/rmap.c: In function 'try_to_unmap_one':
>> mm/rmap.c:1635:14: warning: variable 'pmd_mapped' set but not used [-Wunused-but-set-variable]
1635 | bool pmd_mapped = false;
| ^~~~~~~~~~
vim +/pmd_mapped +1635 mm/rmap.c
b06dc281aa99010 David Hildenbrand 2023-12-20 1619
^1da177e4c3f415 Linus Torvalds 2005-04-16 1620 /*
52629506420ce32 Joonsoo Kim 2014-01-21 1621 * @arg: enum ttu_flags will be passed to this argument
^1da177e4c3f415 Linus Torvalds 2005-04-16 1622 */
2f031c6f042cb8a Matthew Wilcox (Oracle 2022-01-29 1623) static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
52629506420ce32 Joonsoo Kim 2014-01-21 1624 unsigned long address, void *arg)
^1da177e4c3f415 Linus Torvalds 2005-04-16 1625 {
^1da177e4c3f415 Linus Torvalds 2005-04-16 1626 struct mm_struct *mm = vma->vm_mm;
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1627) DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
^1da177e4c3f415 Linus Torvalds 2005-04-16 1628 pte_t pteval;
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1629 struct page *subpage;
6c287605fd56466 David Hildenbrand 2022-05-09 1630 bool anon_exclusive, ret = true;
ac46d4f3c43241f Jérôme Glisse 2018-12-28 1631 struct mmu_notifier_range range;
4708f31885a0d3e Palmer Dabbelt 2020-04-06 1632 enum ttu_flags flags = (enum ttu_flags)(long)arg;
c33c794828f2121 Ryan Roberts 2023-06-12 1633 unsigned long pfn;
935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1634 unsigned long hsz = 0;
87b8388b6693bea Lance Yang 2024-06-10 @1635 bool pmd_mapped = false;
^1da177e4c3f415 Linus Torvalds 2005-04-16 1636
732ed55823fc3ad Hugh Dickins 2021-06-15 1637 /*
732ed55823fc3ad Hugh Dickins 2021-06-15 1638 * When racing against e.g. zap_pte_range() on another cpu,
ca1a0746182c3c0 David Hildenbrand 2023-12-20 1639 * in between its ptep_get_and_clear_full() and folio_remove_rmap_*(),
1fb08ac63beedf5 Yang Shi 2021-06-30 1640 * try_to_unmap() may return before page_mapped() has become false,
732ed55823fc3ad Hugh Dickins 2021-06-15 1641 * if page table locking is skipped: use TTU_SYNC to wait for that.
732ed55823fc3ad Hugh Dickins 2021-06-15 1642 */
732ed55823fc3ad Hugh Dickins 2021-06-15 1643 if (flags & TTU_SYNC)
732ed55823fc3ad Hugh Dickins 2021-06-15 1644 pvmw.flags = PVMW_SYNC;
732ed55823fc3ad Hugh Dickins 2021-06-15 1645
369ea8242c0fb52 Jérôme Glisse 2017-08-31 1646 /*
017b1660df89f5f Mike Kravetz 2018-10-05 1647 * For THP, we have to assume the worse case ie pmd for invalidation.
017b1660df89f5f Mike Kravetz 2018-10-05 1648 * For hugetlb, it could be much worse if we need to do pud
017b1660df89f5f Mike Kravetz 2018-10-05 1649 * invalidation in the case of pmd sharing.
017b1660df89f5f Mike Kravetz 2018-10-05 1650 *
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1651) * Note that the folio can not be freed in this function as call of
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1652) * try_to_unmap() must hold a reference on the folio.
369ea8242c0fb52 Jérôme Glisse 2017-08-31 1653 */
2aff7a4755bed28 Matthew Wilcox (Oracle 2022-02-03 1654) range.end = vma_address_end(&pvmw);
7d4a8be0c4b2b7f Alistair Popple 2023-01-10 1655 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
494334e43c16d63 Hugh Dickins 2021-06-15 1656 address, range.end);
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1657) if (folio_test_hugetlb(folio)) {
017b1660df89f5f Mike Kravetz 2018-10-05 1658 /*
017b1660df89f5f Mike Kravetz 2018-10-05 1659 * If sharing is possible, start and end will be adjusted
017b1660df89f5f Mike Kravetz 2018-10-05 1660 * accordingly.
017b1660df89f5f Mike Kravetz 2018-10-05 1661 */
ac46d4f3c43241f Jérôme Glisse 2018-12-28 1662 adjust_range_if_pmd_sharing_possible(vma, &range.start,
ac46d4f3c43241f Jérôme Glisse 2018-12-28 1663 &range.end);
935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1664
935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1665 /* We need the huge page size for set_huge_pte_at() */
935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1666 hsz = huge_page_size(hstate_vma(vma));
017b1660df89f5f Mike Kravetz 2018-10-05 1667 }
ac46d4f3c43241f Jérôme Glisse 2018-12-28 1668 mmu_notifier_invalidate_range_start(&range);
369ea8242c0fb52 Jérôme Glisse 2017-08-31 1669
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1670 while (page_vma_mapped_walk(&pvmw)) {
^1da177e4c3f415 Linus Torvalds 2005-04-16 1671 /*
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1672) * If the folio is in an mlock()d vma, we must not swap it out.
^1da177e4c3f415 Linus Torvalds 2005-04-16 1673 */
efdb6720b44b2f0 Hugh Dickins 2021-07-11 1674 if (!(flags & TTU_IGNORE_MLOCK) &&
efdb6720b44b2f0 Hugh Dickins 2021-07-11 1675 (vma->vm_flags & VM_LOCKED)) {
cea86fe246b694a Hugh Dickins 2022-02-14 1676 /* Restore the mlock which got missed */
1acbc3f936146d1 Yin Fengwei 2023-09-18 1677 if (!folio_test_large(folio))
1acbc3f936146d1 Yin Fengwei 2023-09-18 1678 mlock_vma_folio(folio, vma);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1679 goto walk_done_err;
b87537d9e2feb30 Hugh Dickins 2015-11-05 1680 }
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1681
87b8388b6693bea Lance Yang 2024-06-10 1682 if (!pvmw.pte) {
87b8388b6693bea Lance Yang 2024-06-10 1683 pmd_mapped = true;
87b8388b6693bea Lance Yang 2024-06-10 1684 if (unmap_huge_pmd_locked(vma, pvmw.address, pvmw.pmd,
87b8388b6693bea Lance Yang 2024-06-10 1685 folio))
87b8388b6693bea Lance Yang 2024-06-10 1686 goto walk_done;
87b8388b6693bea Lance Yang 2024-06-10 1687
87b8388b6693bea Lance Yang 2024-06-10 1688 if (flags & TTU_SPLIT_HUGE_PMD) {
df0f2ce432be374 Lance Yang 2024-06-10 1689 /*
87b8388b6693bea Lance Yang 2024-06-10 1690 * We temporarily have to drop the PTL and start
87b8388b6693bea Lance Yang 2024-06-10 1691 * once again from that now-PTE-mapped page
87b8388b6693bea Lance Yang 2024-06-10 1692 * table.
df0f2ce432be374 Lance Yang 2024-06-10 1693 */
87b8388b6693bea Lance Yang 2024-06-10 1694 split_huge_pmd_locked(vma, pvmw.address,
87b8388b6693bea Lance Yang 2024-06-10 1695 pvmw.pmd, false, folio);
df0f2ce432be374 Lance Yang 2024-06-10 1696 flags &= ~TTU_SPLIT_HUGE_PMD;
df0f2ce432be374 Lance Yang 2024-06-10 1697 page_vma_mapped_walk_restart(&pvmw);
df0f2ce432be374 Lance Yang 2024-06-10 1698 continue;
df0f2ce432be374 Lance Yang 2024-06-10 1699 }
87b8388b6693bea Lance Yang 2024-06-10 1700 }
df0f2ce432be374 Lance Yang 2024-06-10 1701
df0f2ce432be374 Lance Yang 2024-06-10 1702 /* Unexpected PMD-mapped THP? */
df0f2ce432be374 Lance Yang 2024-06-10 1703 VM_BUG_ON_FOLIO(!pvmw.pte, folio);
df0f2ce432be374 Lance Yang 2024-06-10 1704
c33c794828f2121 Ryan Roberts 2023-06-12 1705 pfn = pte_pfn(ptep_get(pvmw.pte));
c33c794828f2121 Ryan Roberts 2023-06-12 1706 subpage = folio_page(folio, pfn - folio_pfn(folio));
785373b4c38719f Linus Torvalds 2017-08-29 1707 address = pvmw.address;
6c287605fd56466 David Hildenbrand 2022-05-09 1708 anon_exclusive = folio_test_anon(folio) &&
6c287605fd56466 David Hildenbrand 2022-05-09 1709 PageAnonExclusive(subpage);
785373b4c38719f Linus Torvalds 2017-08-29 1710
dfc7ab57560da38 Baolin Wang 2022-05-09 1711 if (folio_test_hugetlb(folio)) {
0506c31d0a8443a Baolin Wang 2022-06-20 1712 bool anon = folio_test_anon(folio);
0506c31d0a8443a Baolin Wang 2022-06-20 1713
a00a875925a418b Baolin Wang 2022-05-13 1714 /*
a00a875925a418b Baolin Wang 2022-05-13 1715 * The try_to_unmap() is only passed a hugetlb page
a00a875925a418b Baolin Wang 2022-05-13 1716 * in the case where the hugetlb page is poisoned.
a00a875925a418b Baolin Wang 2022-05-13 1717 */
a00a875925a418b Baolin Wang 2022-05-13 1718 VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage);
017b1660df89f5f Mike Kravetz 2018-10-05 1719 /*
54205e9c5425049 Baolin Wang 2022-05-09 1720 * huge_pmd_unshare may unmap an entire PMD page.
54205e9c5425049 Baolin Wang 2022-05-09 1721 * There is no way of knowing exactly which PMDs may
54205e9c5425049 Baolin Wang 2022-05-09 1722 * be cached for this mm, so we must flush them all.
54205e9c5425049 Baolin Wang 2022-05-09 1723 * start/end were already adjusted above to cover this
54205e9c5425049 Baolin Wang 2022-05-09 1724 * range.
017b1660df89f5f Mike Kravetz 2018-10-05 1725 */
ac46d4f3c43241f Jérôme Glisse 2018-12-28 1726 flush_cache_range(vma, range.start, range.end);
54205e9c5425049 Baolin Wang 2022-05-09 1727
dfc7ab57560da38 Baolin Wang 2022-05-09 1728 /*
dfc7ab57560da38 Baolin Wang 2022-05-09 1729 * To call huge_pmd_unshare, i_mmap_rwsem must be
dfc7ab57560da38 Baolin Wang 2022-05-09 1730 * held in write mode. Caller needs to explicitly
dfc7ab57560da38 Baolin Wang 2022-05-09 1731 * do this outside rmap routines.
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1732 *
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1733 * We also must hold hugetlb vma_lock in write mode.
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1734 * Lock order dictates acquiring vma_lock BEFORE
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1735 * i_mmap_rwsem. We can only try lock here and fail
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1736 * if unsuccessful.
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1737 */
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1738 if (!anon) {
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1739 VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
3ee78e6ad3bc52e Lance Yang 2024-06-10 1740 if (!hugetlb_vma_trylock_write(vma))
3ee78e6ad3bc52e Lance Yang 2024-06-10 1741 goto walk_done_err;
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1742 if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) {
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1743 hugetlb_vma_unlock_write(vma);
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1744 flush_tlb_range(vma,
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1745 range.start, range.end);
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1746 /*
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1747 * The ref count of the PMD page was
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1748 * dropped which is part of the way map
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1749 * counting is done for shared PMDs.
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1750 * Return 'true' here. When there is
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1751 * no other sharing, huge_pmd_unshare
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1752 * returns false and we will unmap the
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1753 * actual page and drop map count
017b1660df89f5f Mike Kravetz 2018-10-05 1754 * to zero.
017b1660df89f5f Mike Kravetz 2018-10-05 1755 */
3ee78e6ad3bc52e Lance Yang 2024-06-10 1756 goto walk_done;
017b1660df89f5f Mike Kravetz 2018-10-05 1757 }
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1758 hugetlb_vma_unlock_write(vma);
40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1759 }
a00a875925a418b Baolin Wang 2022-05-13 1760 pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
54205e9c5425049 Baolin Wang 2022-05-09 1761 } else {
c33c794828f2121 Ryan Roberts 2023-06-12 1762 flush_cache_page(vma, address, pfn);
088b8aa537c2c76 David Hildenbrand 2022-09-01 1763 /* Nuke the page table entry. */
088b8aa537c2c76 David Hildenbrand 2022-09-01 1764 if (should_defer_flush(mm, flags)) {
72b252aed506b8f Mel Gorman 2015-09-04 1765 /*
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1766 * We clear the PTE but do not flush so potentially
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1767) * a remote CPU could still be writing to the folio.
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1768 * If the entry was previously clean then the
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1769 * architecture must guarantee that a clear->dirty
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1770 * transition on a cached TLB entry is written through
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1771 * and traps if the PTE is unmapped.
72b252aed506b8f Mel Gorman 2015-09-04 1772 */
785373b4c38719f Linus Torvalds 2017-08-29 1773 pteval = ptep_get_and_clear(mm, address, pvmw.pte);
72b252aed506b8f Mel Gorman 2015-09-04 1774
f73419bb89d606d Barry Song 2023-07-17 1775 set_tlb_ubc_flush_pending(mm, pteval, address);
72b252aed506b8f Mel Gorman 2015-09-04 1776 } else {
785373b4c38719f Linus Torvalds 2017-08-29 1777 pteval = ptep_clear_flush(vma, address, pvmw.pte);
72b252aed506b8f Mel Gorman 2015-09-04 1778 }
a00a875925a418b Baolin Wang 2022-05-13 1779 }
^1da177e4c3f415 Linus Torvalds 2005-04-16 1780
999dad824c39ed1 Peter Xu 2022-05-12 1781 /*
999dad824c39ed1 Peter Xu 2022-05-12 1782 * Now the pte is cleared. If this pte was uffd-wp armed,
999dad824c39ed1 Peter Xu 2022-05-12 1783 * we may want to replace a none pte with a marker pte if
999dad824c39ed1 Peter Xu 2022-05-12 1784 * it's file-backed, so we don't lose the tracking info.
999dad824c39ed1 Peter Xu 2022-05-12 1785 */
999dad824c39ed1 Peter Xu 2022-05-12 1786 pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval);
999dad824c39ed1 Peter Xu 2022-05-12 1787
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1788) /* Set the dirty flag on the folio now the pte is gone. */
^1da177e4c3f415 Linus Torvalds 2005-04-16 1789 if (pte_dirty(pteval))
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1790) folio_mark_dirty(folio);
^1da177e4c3f415 Linus Torvalds 2005-04-16 1791
365e9c87a982c03 Hugh Dickins 2005-10-29 1792 /* Update high watermark before we lower rss */
365e9c87a982c03 Hugh Dickins 2005-10-29 1793 update_hiwater_rss(mm);
365e9c87a982c03 Hugh Dickins 2005-10-29 1794
6da6b1d4a7df8c3 Naoya Horiguchi 2023-02-21 1795 if (PageHWPoison(subpage) && (flags & TTU_HWPOISON)) {
5fd27b8e7dbcab0 Punit Agrawal 2017-07-06 1796 pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1797) if (folio_test_hugetlb(folio)) {
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1798) hugetlb_count_sub(folio_nr_pages(folio), mm);
935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1799 set_huge_pte_at(mm, address, pvmw.pte, pteval,
935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1800 hsz);
5d317b2b6536592 Naoya Horiguchi 2015-11-05 1801 } else {
a23f517b0e15544 Kefeng Wang 2024-01-11 1802 dec_mm_counter(mm, mm_counter(folio));
785373b4c38719f Linus Torvalds 2017-08-29 1803 set_pte_at(mm, address, pvmw.pte, pteval);
5f24ae585be9856 Naoya Horiguchi 2012-12-12 1804 }
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1805
bce73e4842390f7 Christian Borntraeger 2018-07-13 1806 } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
45961722f8e30ce Konstantin Weitz 2013-04-17 1807 /*
45961722f8e30ce Konstantin Weitz 2013-04-17 1808 * The guest indicated that the page content is of no
45961722f8e30ce Konstantin Weitz 2013-04-17 1809 * interest anymore. Simply discard the pte, vmscan
45961722f8e30ce Konstantin Weitz 2013-04-17 1810 * will take care of the rest.
bce73e4842390f7 Christian Borntraeger 2018-07-13 1811 * A future reference will then fault in a new zero
bce73e4842390f7 Christian Borntraeger 2018-07-13 1812 * page. When userfaultfd is active, we must not drop
bce73e4842390f7 Christian Borntraeger 2018-07-13 1813 * this page though, as its main user (postcopy
bce73e4842390f7 Christian Borntraeger 2018-07-13 1814 * migration) will not expect userfaults on already
bce73e4842390f7 Christian Borntraeger 2018-07-13 1815 * copied pages.
45961722f8e30ce Konstantin Weitz 2013-04-17 1816 */
a23f517b0e15544 Kefeng Wang 2024-01-11 1817 dec_mm_counter(mm, mm_counter(folio));
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1818) } else if (folio_test_anon(folio)) {
cfeed8ffe55b37f David Hildenbrand 2023-08-21 1819 swp_entry_t entry = page_swap_entry(subpage);
179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1820 pte_t swp_pte;
^1da177e4c3f415 Linus Torvalds 2005-04-16 1821 /*
^1da177e4c3f415 Linus Torvalds 2005-04-16 1822 * Store the swap location in the pte.
^1da177e4c3f415 Linus Torvalds 2005-04-16 1823 * See handle_pte_fault() ...
^1da177e4c3f415 Linus Torvalds 2005-04-16 1824 */
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1825) if (unlikely(folio_test_swapbacked(folio) !=
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1826) folio_test_swapcache(folio))) {
fa687ca2801a5b5 Lance Yang 2024-06-13 1827 WARN_ON_ONCE(1);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1828 goto walk_done_err;
eb94a8784427b28 Minchan Kim 2017-05-03 1829 }
854e9ed09dedf0c Minchan Kim 2016-01-15 1830
802a3a92ad7ac0b Shaohua Li 2017-05-03 1831 /* MADV_FREE page check */
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1832) if (!folio_test_swapbacked(folio)) {
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1833 int ref_count, map_count;
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1834
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1835 /*
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1836 * Synchronize with gup_pte_range():
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1837 * - clear PTE; barrier; read refcount
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1838 * - inc refcount; barrier; read PTE
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1839 */
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1840 smp_mb();
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1841
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1842 ref_count = folio_ref_count(folio);
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1843 map_count = folio_mapcount(folio);
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1844
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1845 /*
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1846 * Order reads for page refcount and dirty flag
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1847 * (see comments in __remove_mapping()).
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1848 */
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1849 smp_rmb();
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1850
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1851 /*
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1852 * The only page refs must be one from isolation
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1853 * plus the rmap(s) (dropped by discard:).
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1854 */
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1855 if (ref_count == 1 + map_count &&
6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1856 !folio_test_dirty(folio)) {
854e9ed09dedf0c Minchan Kim 2016-01-15 1857 dec_mm_counter(mm, MM_ANONPAGES);
854e9ed09dedf0c Minchan Kim 2016-01-15 1858 goto discard;
854e9ed09dedf0c Minchan Kim 2016-01-15 1859 }
854e9ed09dedf0c Minchan Kim 2016-01-15 1860
802a3a92ad7ac0b Shaohua Li 2017-05-03 1861 /*
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1862) * If the folio was redirtied, it cannot be
802a3a92ad7ac0b Shaohua Li 2017-05-03 1863 * discarded. Remap the page to page table.
802a3a92ad7ac0b Shaohua Li 2017-05-03 1864 */
785373b4c38719f Linus Torvalds 2017-08-29 1865 set_pte_at(mm, address, pvmw.pte, pteval);
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1866) folio_set_swapbacked(folio);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1867 goto walk_done_err;
802a3a92ad7ac0b Shaohua Li 2017-05-03 1868 }
802a3a92ad7ac0b Shaohua Li 2017-05-03 1869
570a335b8e22579 Hugh Dickins 2009-12-14 1870 if (swap_duplicate(entry) < 0) {
785373b4c38719f Linus Torvalds 2017-08-29 1871 set_pte_at(mm, address, pvmw.pte, pteval);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1872 goto walk_done_err;
570a335b8e22579 Hugh Dickins 2009-12-14 1873 }
ca827d55ebaa24d Khalid Aziz 2018-02-21 1874 if (arch_unmap_one(mm, vma, address, pteval) < 0) {
322842ea3c72649 David Hildenbrand 2022-05-09 1875 swap_free(entry);
ca827d55ebaa24d Khalid Aziz 2018-02-21 1876 set_pte_at(mm, address, pvmw.pte, pteval);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1877 goto walk_done_err;
ca827d55ebaa24d Khalid Aziz 2018-02-21 1878 }
088b8aa537c2c76 David Hildenbrand 2022-09-01 1879
e3b4b1374f87c71 David Hildenbrand 2023-12-20 1880 /* See folio_try_share_anon_rmap(): clear PTE first. */
6c287605fd56466 David Hildenbrand 2022-05-09 1881 if (anon_exclusive &&
e3b4b1374f87c71 David Hildenbrand 2023-12-20 1882 folio_try_share_anon_rmap_pte(folio, subpage)) {
6c287605fd56466 David Hildenbrand 2022-05-09 1883 swap_free(entry);
6c287605fd56466 David Hildenbrand 2022-05-09 1884 set_pte_at(mm, address, pvmw.pte, pteval);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1885 goto walk_done_err;
6c287605fd56466 David Hildenbrand 2022-05-09 1886 }
^1da177e4c3f415 Linus Torvalds 2005-04-16 1887 if (list_empty(&mm->mmlist)) {
^1da177e4c3f415 Linus Torvalds 2005-04-16 1888 spin_lock(&mmlist_lock);
f412ac08c9861b4 Hugh Dickins 2005-10-29 1889 if (list_empty(&mm->mmlist))
^1da177e4c3f415 Linus Torvalds 2005-04-16 1890 list_add(&mm->mmlist, &init_mm.mmlist);
^1da177e4c3f415 Linus Torvalds 2005-04-16 1891 spin_unlock(&mmlist_lock);
^1da177e4c3f415 Linus Torvalds 2005-04-16 1892 }
d559db086ff5be9 KAMEZAWA Hiroyuki 2010-03-05 1893 dec_mm_counter(mm, MM_ANONPAGES);
b084d4353ff99d8 KAMEZAWA Hiroyuki 2010-03-05 1894 inc_mm_counter(mm, MM_SWAPENTS);
179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1895 swp_pte = swp_entry_to_pte(entry);
1493a1913e34b0a David Hildenbrand 2022-05-09 1896 if (anon_exclusive)
1493a1913e34b0a David Hildenbrand 2022-05-09 1897 swp_pte = pte_swp_mkexclusive(swp_pte);
179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1898 if (pte_soft_dirty(pteval))
179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1899 swp_pte = pte_swp_mksoft_dirty(swp_pte);
f45ec5ff16a75f9 Peter Xu 2020-04-06 1900 if (pte_uffd_wp(pteval))
f45ec5ff16a75f9 Peter Xu 2020-04-06 1901 swp_pte = pte_swp_mkuffd_wp(swp_pte);
785373b4c38719f Linus Torvalds 2017-08-29 1902 set_pte_at(mm, address, pvmw.pte, swp_pte);
0f10851ea475e08 Jérôme Glisse 2017-11-15 1903 } else {
0f10851ea475e08 Jérôme Glisse 2017-11-15 1904 /*
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1905) * This is a locked file-backed folio,
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1906) * so it cannot be removed from the page
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1907) * cache and replaced by a new folio before
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1908) * mmu_notifier_invalidate_range_end, so no
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1909) * concurrent thread might update its page table
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1910) * to point at a new folio while a device is
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1911) * still using this folio.
0f10851ea475e08 Jérôme Glisse 2017-11-15 1912 *
ee65728e103bb7d Mike Rapoport 2022-06-27 1913 * See Documentation/mm/mmu_notifier.rst
0f10851ea475e08 Jérôme Glisse 2017-11-15 1914 */
6b27cc6c66abf0f Kefeng Wang 2024-01-11 1915 dec_mm_counter(mm, mm_counter_file(folio));
0f10851ea475e08 Jérôme Glisse 2017-11-15 1916 }
854e9ed09dedf0c Minchan Kim 2016-01-15 1917 discard:
e135826b2da0cf2 David Hildenbrand 2023-12-20 1918 if (unlikely(folio_test_hugetlb(folio)))
e135826b2da0cf2 David Hildenbrand 2023-12-20 1919 hugetlb_remove_rmap(folio);
e135826b2da0cf2 David Hildenbrand 2023-12-20 1920 else
ca1a0746182c3c0 David Hildenbrand 2023-12-20 1921 folio_remove_rmap_pte(folio, subpage, vma);
b74355078b65542 Hugh Dickins 2022-02-14 1922 if (vma->vm_flags & VM_LOCKED)
96f97c438f61ddb Lorenzo Stoakes 2023-01-12 1923 mlock_drain_local();
869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1924) folio_put(folio);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1925 continue;
3ee78e6ad3bc52e Lance Yang 2024-06-10 1926 walk_done_err:
3ee78e6ad3bc52e Lance Yang 2024-06-10 1927 ret = false;
3ee78e6ad3bc52e Lance Yang 2024-06-10 1928 walk_done:
3ee78e6ad3bc52e Lance Yang 2024-06-10 1929 page_vma_mapped_walk_done(&pvmw);
3ee78e6ad3bc52e Lance Yang 2024-06-10 1930 break;
c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1931 }
369ea8242c0fb52 Jérôme Glisse 2017-08-31 1932
ac46d4f3c43241f Jérôme Glisse 2018-12-28 1933 mmu_notifier_invalidate_range_end(&range);
369ea8242c0fb52 Jérôme Glisse 2017-08-31 1934
caed0f486e582ee KOSAKI Motohiro 2009-12-14 1935 return ret;
^1da177e4c3f415 Linus Torvalds 2005-04-16 1936 }
^1da177e4c3f415 Linus Torvalds 2005-04-16 1937
:::::: The code at line 1635 was first introduced by commit
:::::: 87b8388b6693beaad43d5d3f41534d5e042f9388 mm/vmscan: avoid split lazyfree THP during shrink_folio_list()
:::::: TO: Lance Yang <ioworker0@gmail.com>
:::::: CC: Andrew Morton <akpm@linux-foundation.org>
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [akpm-mm:mm-unstable 201/281] mm/rmap.c:1635:14: warning: variable 'pmd_mapped' set but not used
2024-06-14 8:37 [akpm-mm:mm-unstable 201/281] mm/rmap.c:1635:14: warning: variable 'pmd_mapped' set but not used kernel test robot
@ 2024-06-14 8:59 ` Lance Yang
0 siblings, 0 replies; 2+ messages in thread
From: Lance Yang @ 2024-06-14 8:59 UTC (permalink / raw)
To: kernel test robot
Cc: oe-kbuild-all, Andrew Morton, Linux Memory Management List
Hi all,
This issue appeared in the v7[1], but it has been fixed in the v8[2],
so there's no need for concern.
[1] https://lore.kernel.org/linux-mm/20240610120809.66601-1-ioworker0@gmail.com
[2] https://lore.kernel.org/linux-mm/20240614015138.31461-4-ioworker0@gmail.com
Thanks,
Lance
On Fri, Jun 14, 2024 at 4:37 PM kernel test robot <lkp@intel.com> wrote:
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
> head: 8d0a686ea94347949eb0b689bb2a7c6028c0fa28
> commit: fa687ca2801a5b5ec92912abc362507242fd5cbc [201/281] mm-vmscan-avoid-split-lazyfree-thp-during-shrink_folio_list-fix
> config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240614/202406141650.B5cBNrbw-lkp@intel.com/config)
> compiler: or1k-linux-gcc (GCC) 13.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240614/202406141650.B5cBNrbw-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202406141650.B5cBNrbw-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> mm/rmap.c: In function 'try_to_unmap_one':
> >> mm/rmap.c:1635:14: warning: variable 'pmd_mapped' set but not used [-Wunused-but-set-variable]
> 1635 | bool pmd_mapped = false;
> | ^~~~~~~~~~
>
>
> vim +/pmd_mapped +1635 mm/rmap.c
>
> b06dc281aa99010 David Hildenbrand 2023-12-20 1619
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1620 /*
> 52629506420ce32 Joonsoo Kim 2014-01-21 1621 * @arg: enum ttu_flags will be passed to this argument
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1622 */
> 2f031c6f042cb8a Matthew Wilcox (Oracle 2022-01-29 1623) static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> 52629506420ce32 Joonsoo Kim 2014-01-21 1624 unsigned long address, void *arg)
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1625 {
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1626 struct mm_struct *mm = vma->vm_mm;
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1627) DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1628 pte_t pteval;
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1629 struct page *subpage;
> 6c287605fd56466 David Hildenbrand 2022-05-09 1630 bool anon_exclusive, ret = true;
> ac46d4f3c43241f Jérôme Glisse 2018-12-28 1631 struct mmu_notifier_range range;
> 4708f31885a0d3e Palmer Dabbelt 2020-04-06 1632 enum ttu_flags flags = (enum ttu_flags)(long)arg;
> c33c794828f2121 Ryan Roberts 2023-06-12 1633 unsigned long pfn;
> 935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1634 unsigned long hsz = 0;
> 87b8388b6693bea Lance Yang 2024-06-10 @1635 bool pmd_mapped = false;
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1636
> 732ed55823fc3ad Hugh Dickins 2021-06-15 1637 /*
> 732ed55823fc3ad Hugh Dickins 2021-06-15 1638 * When racing against e.g. zap_pte_range() on another cpu,
> ca1a0746182c3c0 David Hildenbrand 2023-12-20 1639 * in between its ptep_get_and_clear_full() and folio_remove_rmap_*(),
> 1fb08ac63beedf5 Yang Shi 2021-06-30 1640 * try_to_unmap() may return before page_mapped() has become false,
> 732ed55823fc3ad Hugh Dickins 2021-06-15 1641 * if page table locking is skipped: use TTU_SYNC to wait for that.
> 732ed55823fc3ad Hugh Dickins 2021-06-15 1642 */
> 732ed55823fc3ad Hugh Dickins 2021-06-15 1643 if (flags & TTU_SYNC)
> 732ed55823fc3ad Hugh Dickins 2021-06-15 1644 pvmw.flags = PVMW_SYNC;
> 732ed55823fc3ad Hugh Dickins 2021-06-15 1645
> 369ea8242c0fb52 Jérôme Glisse 2017-08-31 1646 /*
> 017b1660df89f5f Mike Kravetz 2018-10-05 1647 * For THP, we have to assume the worse case ie pmd for invalidation.
> 017b1660df89f5f Mike Kravetz 2018-10-05 1648 * For hugetlb, it could be much worse if we need to do pud
> 017b1660df89f5f Mike Kravetz 2018-10-05 1649 * invalidation in the case of pmd sharing.
> 017b1660df89f5f Mike Kravetz 2018-10-05 1650 *
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1651) * Note that the folio can not be freed in this function as call of
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1652) * try_to_unmap() must hold a reference on the folio.
> 369ea8242c0fb52 Jérôme Glisse 2017-08-31 1653 */
> 2aff7a4755bed28 Matthew Wilcox (Oracle 2022-02-03 1654) range.end = vma_address_end(&pvmw);
> 7d4a8be0c4b2b7f Alistair Popple 2023-01-10 1655 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
> 494334e43c16d63 Hugh Dickins 2021-06-15 1656 address, range.end);
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1657) if (folio_test_hugetlb(folio)) {
> 017b1660df89f5f Mike Kravetz 2018-10-05 1658 /*
> 017b1660df89f5f Mike Kravetz 2018-10-05 1659 * If sharing is possible, start and end will be adjusted
> 017b1660df89f5f Mike Kravetz 2018-10-05 1660 * accordingly.
> 017b1660df89f5f Mike Kravetz 2018-10-05 1661 */
> ac46d4f3c43241f Jérôme Glisse 2018-12-28 1662 adjust_range_if_pmd_sharing_possible(vma, &range.start,
> ac46d4f3c43241f Jérôme Glisse 2018-12-28 1663 &range.end);
> 935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1664
> 935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1665 /* We need the huge page size for set_huge_pte_at() */
> 935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1666 hsz = huge_page_size(hstate_vma(vma));
> 017b1660df89f5f Mike Kravetz 2018-10-05 1667 }
> ac46d4f3c43241f Jérôme Glisse 2018-12-28 1668 mmu_notifier_invalidate_range_start(&range);
> 369ea8242c0fb52 Jérôme Glisse 2017-08-31 1669
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1670 while (page_vma_mapped_walk(&pvmw)) {
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1671 /*
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1672) * If the folio is in an mlock()d vma, we must not swap it out.
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1673 */
> efdb6720b44b2f0 Hugh Dickins 2021-07-11 1674 if (!(flags & TTU_IGNORE_MLOCK) &&
> efdb6720b44b2f0 Hugh Dickins 2021-07-11 1675 (vma->vm_flags & VM_LOCKED)) {
> cea86fe246b694a Hugh Dickins 2022-02-14 1676 /* Restore the mlock which got missed */
> 1acbc3f936146d1 Yin Fengwei 2023-09-18 1677 if (!folio_test_large(folio))
> 1acbc3f936146d1 Yin Fengwei 2023-09-18 1678 mlock_vma_folio(folio, vma);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1679 goto walk_done_err;
> b87537d9e2feb30 Hugh Dickins 2015-11-05 1680 }
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1681
> 87b8388b6693bea Lance Yang 2024-06-10 1682 if (!pvmw.pte) {
> 87b8388b6693bea Lance Yang 2024-06-10 1683 pmd_mapped = true;
> 87b8388b6693bea Lance Yang 2024-06-10 1684 if (unmap_huge_pmd_locked(vma, pvmw.address, pvmw.pmd,
> 87b8388b6693bea Lance Yang 2024-06-10 1685 folio))
> 87b8388b6693bea Lance Yang 2024-06-10 1686 goto walk_done;
> 87b8388b6693bea Lance Yang 2024-06-10 1687
> 87b8388b6693bea Lance Yang 2024-06-10 1688 if (flags & TTU_SPLIT_HUGE_PMD) {
> df0f2ce432be374 Lance Yang 2024-06-10 1689 /*
> 87b8388b6693bea Lance Yang 2024-06-10 1690 * We temporarily have to drop the PTL and start
> 87b8388b6693bea Lance Yang 2024-06-10 1691 * once again from that now-PTE-mapped page
> 87b8388b6693bea Lance Yang 2024-06-10 1692 * table.
> df0f2ce432be374 Lance Yang 2024-06-10 1693 */
> 87b8388b6693bea Lance Yang 2024-06-10 1694 split_huge_pmd_locked(vma, pvmw.address,
> 87b8388b6693bea Lance Yang 2024-06-10 1695 pvmw.pmd, false, folio);
> df0f2ce432be374 Lance Yang 2024-06-10 1696 flags &= ~TTU_SPLIT_HUGE_PMD;
> df0f2ce432be374 Lance Yang 2024-06-10 1697 page_vma_mapped_walk_restart(&pvmw);
> df0f2ce432be374 Lance Yang 2024-06-10 1698 continue;
> df0f2ce432be374 Lance Yang 2024-06-10 1699 }
> 87b8388b6693bea Lance Yang 2024-06-10 1700 }
> df0f2ce432be374 Lance Yang 2024-06-10 1701
> df0f2ce432be374 Lance Yang 2024-06-10 1702 /* Unexpected PMD-mapped THP? */
> df0f2ce432be374 Lance Yang 2024-06-10 1703 VM_BUG_ON_FOLIO(!pvmw.pte, folio);
> df0f2ce432be374 Lance Yang 2024-06-10 1704
> c33c794828f2121 Ryan Roberts 2023-06-12 1705 pfn = pte_pfn(ptep_get(pvmw.pte));
> c33c794828f2121 Ryan Roberts 2023-06-12 1706 subpage = folio_page(folio, pfn - folio_pfn(folio));
> 785373b4c38719f Linus Torvalds 2017-08-29 1707 address = pvmw.address;
> 6c287605fd56466 David Hildenbrand 2022-05-09 1708 anon_exclusive = folio_test_anon(folio) &&
> 6c287605fd56466 David Hildenbrand 2022-05-09 1709 PageAnonExclusive(subpage);
> 785373b4c38719f Linus Torvalds 2017-08-29 1710
> dfc7ab57560da38 Baolin Wang 2022-05-09 1711 if (folio_test_hugetlb(folio)) {
> 0506c31d0a8443a Baolin Wang 2022-06-20 1712 bool anon = folio_test_anon(folio);
> 0506c31d0a8443a Baolin Wang 2022-06-20 1713
> a00a875925a418b Baolin Wang 2022-05-13 1714 /*
> a00a875925a418b Baolin Wang 2022-05-13 1715 * The try_to_unmap() is only passed a hugetlb page
> a00a875925a418b Baolin Wang 2022-05-13 1716 * in the case where the hugetlb page is poisoned.
> a00a875925a418b Baolin Wang 2022-05-13 1717 */
> a00a875925a418b Baolin Wang 2022-05-13 1718 VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage);
> 017b1660df89f5f Mike Kravetz 2018-10-05 1719 /*
> 54205e9c5425049 Baolin Wang 2022-05-09 1720 * huge_pmd_unshare may unmap an entire PMD page.
> 54205e9c5425049 Baolin Wang 2022-05-09 1721 * There is no way of knowing exactly which PMDs may
> 54205e9c5425049 Baolin Wang 2022-05-09 1722 * be cached for this mm, so we must flush them all.
> 54205e9c5425049 Baolin Wang 2022-05-09 1723 * start/end were already adjusted above to cover this
> 54205e9c5425049 Baolin Wang 2022-05-09 1724 * range.
> 017b1660df89f5f Mike Kravetz 2018-10-05 1725 */
> ac46d4f3c43241f Jérôme Glisse 2018-12-28 1726 flush_cache_range(vma, range.start, range.end);
> 54205e9c5425049 Baolin Wang 2022-05-09 1727
> dfc7ab57560da38 Baolin Wang 2022-05-09 1728 /*
> dfc7ab57560da38 Baolin Wang 2022-05-09 1729 * To call huge_pmd_unshare, i_mmap_rwsem must be
> dfc7ab57560da38 Baolin Wang 2022-05-09 1730 * held in write mode. Caller needs to explicitly
> dfc7ab57560da38 Baolin Wang 2022-05-09 1731 * do this outside rmap routines.
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1732 *
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1733 * We also must hold hugetlb vma_lock in write mode.
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1734 * Lock order dictates acquiring vma_lock BEFORE
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1735 * i_mmap_rwsem. We can only try lock here and fail
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1736 * if unsuccessful.
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1737 */
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1738 if (!anon) {
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1739 VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1740 if (!hugetlb_vma_trylock_write(vma))
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1741 goto walk_done_err;
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1742 if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) {
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1743 hugetlb_vma_unlock_write(vma);
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1744 flush_tlb_range(vma,
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1745 range.start, range.end);
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1746 /*
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1747 * The ref count of the PMD page was
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1748 * dropped which is part of the way map
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1749 * counting is done for shared PMDs.
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1750 * Return 'true' here. When there is
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1751 * no other sharing, huge_pmd_unshare
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1752 * returns false and we will unmap the
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1753 * actual page and drop map count
> 017b1660df89f5f Mike Kravetz 2018-10-05 1754 * to zero.
> 017b1660df89f5f Mike Kravetz 2018-10-05 1755 */
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1756 goto walk_done;
> 017b1660df89f5f Mike Kravetz 2018-10-05 1757 }
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1758 hugetlb_vma_unlock_write(vma);
> 40549ba8f8e0ed1 Mike Kravetz 2022-09-14 1759 }
> a00a875925a418b Baolin Wang 2022-05-13 1760 pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
> 54205e9c5425049 Baolin Wang 2022-05-09 1761 } else {
> c33c794828f2121 Ryan Roberts 2023-06-12 1762 flush_cache_page(vma, address, pfn);
> 088b8aa537c2c76 David Hildenbrand 2022-09-01 1763 /* Nuke the page table entry. */
> 088b8aa537c2c76 David Hildenbrand 2022-09-01 1764 if (should_defer_flush(mm, flags)) {
> 72b252aed506b8f Mel Gorman 2015-09-04 1765 /*
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1766 * We clear the PTE but do not flush so potentially
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1767) * a remote CPU could still be writing to the folio.
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1768 * If the entry was previously clean then the
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1769 * architecture must guarantee that a clear->dirty
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1770 * transition on a cached TLB entry is written through
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1771 * and traps if the PTE is unmapped.
> 72b252aed506b8f Mel Gorman 2015-09-04 1772 */
> 785373b4c38719f Linus Torvalds 2017-08-29 1773 pteval = ptep_get_and_clear(mm, address, pvmw.pte);
> 72b252aed506b8f Mel Gorman 2015-09-04 1774
> f73419bb89d606d Barry Song 2023-07-17 1775 set_tlb_ubc_flush_pending(mm, pteval, address);
> 72b252aed506b8f Mel Gorman 2015-09-04 1776 } else {
> 785373b4c38719f Linus Torvalds 2017-08-29 1777 pteval = ptep_clear_flush(vma, address, pvmw.pte);
> 72b252aed506b8f Mel Gorman 2015-09-04 1778 }
> a00a875925a418b Baolin Wang 2022-05-13 1779 }
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1780
> 999dad824c39ed1 Peter Xu 2022-05-12 1781 /*
> 999dad824c39ed1 Peter Xu 2022-05-12 1782 * Now the pte is cleared. If this pte was uffd-wp armed,
> 999dad824c39ed1 Peter Xu 2022-05-12 1783 * we may want to replace a none pte with a marker pte if
> 999dad824c39ed1 Peter Xu 2022-05-12 1784 * it's file-backed, so we don't lose the tracking info.
> 999dad824c39ed1 Peter Xu 2022-05-12 1785 */
> 999dad824c39ed1 Peter Xu 2022-05-12 1786 pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval);
> 999dad824c39ed1 Peter Xu 2022-05-12 1787
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1788) /* Set the dirty flag on the folio now the pte is gone. */
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1789 if (pte_dirty(pteval))
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1790) folio_mark_dirty(folio);
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1791
> 365e9c87a982c03 Hugh Dickins 2005-10-29 1792 /* Update high watermark before we lower rss */
> 365e9c87a982c03 Hugh Dickins 2005-10-29 1793 update_hiwater_rss(mm);
> 365e9c87a982c03 Hugh Dickins 2005-10-29 1794
> 6da6b1d4a7df8c3 Naoya Horiguchi 2023-02-21 1795 if (PageHWPoison(subpage) && (flags & TTU_HWPOISON)) {
> 5fd27b8e7dbcab0 Punit Agrawal 2017-07-06 1796 pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1797) if (folio_test_hugetlb(folio)) {
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1798) hugetlb_count_sub(folio_nr_pages(folio), mm);
> 935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1799 set_huge_pte_at(mm, address, pvmw.pte, pteval,
> 935d4f0c6dc8b35 Ryan Roberts 2023-09-22 1800 hsz);
> 5d317b2b6536592 Naoya Horiguchi 2015-11-05 1801 } else {
> a23f517b0e15544 Kefeng Wang 2024-01-11 1802 dec_mm_counter(mm, mm_counter(folio));
> 785373b4c38719f Linus Torvalds 2017-08-29 1803 set_pte_at(mm, address, pvmw.pte, pteval);
> 5f24ae585be9856 Naoya Horiguchi 2012-12-12 1804 }
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1805
> bce73e4842390f7 Christian Borntraeger 2018-07-13 1806 } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
> 45961722f8e30ce Konstantin Weitz 2013-04-17 1807 /*
> 45961722f8e30ce Konstantin Weitz 2013-04-17 1808 * The guest indicated that the page content is of no
> 45961722f8e30ce Konstantin Weitz 2013-04-17 1809 * interest anymore. Simply discard the pte, vmscan
> 45961722f8e30ce Konstantin Weitz 2013-04-17 1810 * will take care of the rest.
> bce73e4842390f7 Christian Borntraeger 2018-07-13 1811 * A future reference will then fault in a new zero
> bce73e4842390f7 Christian Borntraeger 2018-07-13 1812 * page. When userfaultfd is active, we must not drop
> bce73e4842390f7 Christian Borntraeger 2018-07-13 1813 * this page though, as its main user (postcopy
> bce73e4842390f7 Christian Borntraeger 2018-07-13 1814 * migration) will not expect userfaults on already
> bce73e4842390f7 Christian Borntraeger 2018-07-13 1815 * copied pages.
> 45961722f8e30ce Konstantin Weitz 2013-04-17 1816 */
> a23f517b0e15544 Kefeng Wang 2024-01-11 1817 dec_mm_counter(mm, mm_counter(folio));
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1818) } else if (folio_test_anon(folio)) {
> cfeed8ffe55b37f David Hildenbrand 2023-08-21 1819 swp_entry_t entry = page_swap_entry(subpage);
> 179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1820 pte_t swp_pte;
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1821 /*
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1822 * Store the swap location in the pte.
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1823 * See handle_pte_fault() ...
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1824 */
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1825) if (unlikely(folio_test_swapbacked(folio) !=
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1826) folio_test_swapcache(folio))) {
> fa687ca2801a5b5 Lance Yang 2024-06-13 1827 WARN_ON_ONCE(1);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1828 goto walk_done_err;
> eb94a8784427b28 Minchan Kim 2017-05-03 1829 }
> 854e9ed09dedf0c Minchan Kim 2016-01-15 1830
> 802a3a92ad7ac0b Shaohua Li 2017-05-03 1831 /* MADV_FREE page check */
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1832) if (!folio_test_swapbacked(folio)) {
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1833 int ref_count, map_count;
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1834
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1835 /*
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1836 * Synchronize with gup_pte_range():
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1837 * - clear PTE; barrier; read refcount
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1838 * - inc refcount; barrier; read PTE
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1839 */
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1840 smp_mb();
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1841
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1842 ref_count = folio_ref_count(folio);
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1843 map_count = folio_mapcount(folio);
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1844
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1845 /*
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1846 * Order reads for page refcount and dirty flag
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1847 * (see comments in __remove_mapping()).
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1848 */
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1849 smp_rmb();
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1850
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1851 /*
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1852 * The only page refs must be one from isolation
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1853 * plus the rmap(s) (dropped by discard:).
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1854 */
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1855 if (ref_count == 1 + map_count &&
> 6c8e2a256915a22 Mauricio Faria de Oliveira 2022-03-24 1856 !folio_test_dirty(folio)) {
> 854e9ed09dedf0c Minchan Kim 2016-01-15 1857 dec_mm_counter(mm, MM_ANONPAGES);
> 854e9ed09dedf0c Minchan Kim 2016-01-15 1858 goto discard;
> 854e9ed09dedf0c Minchan Kim 2016-01-15 1859 }
> 854e9ed09dedf0c Minchan Kim 2016-01-15 1860
> 802a3a92ad7ac0b Shaohua Li 2017-05-03 1861 /*
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1862) * If the folio was redirtied, it cannot be
> 802a3a92ad7ac0b Shaohua Li 2017-05-03 1863 * discarded. Remap the page to page table.
> 802a3a92ad7ac0b Shaohua Li 2017-05-03 1864 */
> 785373b4c38719f Linus Torvalds 2017-08-29 1865 set_pte_at(mm, address, pvmw.pte, pteval);
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1866) folio_set_swapbacked(folio);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1867 goto walk_done_err;
> 802a3a92ad7ac0b Shaohua Li 2017-05-03 1868 }
> 802a3a92ad7ac0b Shaohua Li 2017-05-03 1869
> 570a335b8e22579 Hugh Dickins 2009-12-14 1870 if (swap_duplicate(entry) < 0) {
> 785373b4c38719f Linus Torvalds 2017-08-29 1871 set_pte_at(mm, address, pvmw.pte, pteval);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1872 goto walk_done_err;
> 570a335b8e22579 Hugh Dickins 2009-12-14 1873 }
> ca827d55ebaa24d Khalid Aziz 2018-02-21 1874 if (arch_unmap_one(mm, vma, address, pteval) < 0) {
> 322842ea3c72649 David Hildenbrand 2022-05-09 1875 swap_free(entry);
> ca827d55ebaa24d Khalid Aziz 2018-02-21 1876 set_pte_at(mm, address, pvmw.pte, pteval);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1877 goto walk_done_err;
> ca827d55ebaa24d Khalid Aziz 2018-02-21 1878 }
> 088b8aa537c2c76 David Hildenbrand 2022-09-01 1879
> e3b4b1374f87c71 David Hildenbrand 2023-12-20 1880 /* See folio_try_share_anon_rmap(): clear PTE first. */
> 6c287605fd56466 David Hildenbrand 2022-05-09 1881 if (anon_exclusive &&
> e3b4b1374f87c71 David Hildenbrand 2023-12-20 1882 folio_try_share_anon_rmap_pte(folio, subpage)) {
> 6c287605fd56466 David Hildenbrand 2022-05-09 1883 swap_free(entry);
> 6c287605fd56466 David Hildenbrand 2022-05-09 1884 set_pte_at(mm, address, pvmw.pte, pteval);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1885 goto walk_done_err;
> 6c287605fd56466 David Hildenbrand 2022-05-09 1886 }
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1887 if (list_empty(&mm->mmlist)) {
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1888 spin_lock(&mmlist_lock);
> f412ac08c9861b4 Hugh Dickins 2005-10-29 1889 if (list_empty(&mm->mmlist))
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1890 list_add(&mm->mmlist, &init_mm.mmlist);
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1891 spin_unlock(&mmlist_lock);
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1892 }
> d559db086ff5be9 KAMEZAWA Hiroyuki 2010-03-05 1893 dec_mm_counter(mm, MM_ANONPAGES);
> b084d4353ff99d8 KAMEZAWA Hiroyuki 2010-03-05 1894 inc_mm_counter(mm, MM_SWAPENTS);
> 179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1895 swp_pte = swp_entry_to_pte(entry);
> 1493a1913e34b0a David Hildenbrand 2022-05-09 1896 if (anon_exclusive)
> 1493a1913e34b0a David Hildenbrand 2022-05-09 1897 swp_pte = pte_swp_mkexclusive(swp_pte);
> 179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1898 if (pte_soft_dirty(pteval))
> 179ef71cbc08525 Cyrill Gorcunov 2013-08-13 1899 swp_pte = pte_swp_mksoft_dirty(swp_pte);
> f45ec5ff16a75f9 Peter Xu 2020-04-06 1900 if (pte_uffd_wp(pteval))
> f45ec5ff16a75f9 Peter Xu 2020-04-06 1901 swp_pte = pte_swp_mkuffd_wp(swp_pte);
> 785373b4c38719f Linus Torvalds 2017-08-29 1902 set_pte_at(mm, address, pvmw.pte, swp_pte);
> 0f10851ea475e08 Jérôme Glisse 2017-11-15 1903 } else {
> 0f10851ea475e08 Jérôme Glisse 2017-11-15 1904 /*
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1905) * This is a locked file-backed folio,
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1906) * so it cannot be removed from the page
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1907) * cache and replaced by a new folio before
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1908) * mmu_notifier_invalidate_range_end, so no
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1909) * concurrent thread might update its page table
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1910) * to point at a new folio while a device is
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1911) * still using this folio.
> 0f10851ea475e08 Jérôme Glisse 2017-11-15 1912 *
> ee65728e103bb7d Mike Rapoport 2022-06-27 1913 * See Documentation/mm/mmu_notifier.rst
> 0f10851ea475e08 Jérôme Glisse 2017-11-15 1914 */
> 6b27cc6c66abf0f Kefeng Wang 2024-01-11 1915 dec_mm_counter(mm, mm_counter_file(folio));
> 0f10851ea475e08 Jérôme Glisse 2017-11-15 1916 }
> 854e9ed09dedf0c Minchan Kim 2016-01-15 1917 discard:
> e135826b2da0cf2 David Hildenbrand 2023-12-20 1918 if (unlikely(folio_test_hugetlb(folio)))
> e135826b2da0cf2 David Hildenbrand 2023-12-20 1919 hugetlb_remove_rmap(folio);
> e135826b2da0cf2 David Hildenbrand 2023-12-20 1920 else
> ca1a0746182c3c0 David Hildenbrand 2023-12-20 1921 folio_remove_rmap_pte(folio, subpage, vma);
> b74355078b65542 Hugh Dickins 2022-02-14 1922 if (vma->vm_flags & VM_LOCKED)
> 96f97c438f61ddb Lorenzo Stoakes 2023-01-12 1923 mlock_drain_local();
> 869f7ee6f647734 Matthew Wilcox (Oracle 2022-02-15 1924) folio_put(folio);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1925 continue;
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1926 walk_done_err:
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1927 ret = false;
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1928 walk_done:
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1929 page_vma_mapped_walk_done(&pvmw);
> 3ee78e6ad3bc52e Lance Yang 2024-06-10 1930 break;
> c7ab0d2fdc84026 Kirill A. Shutemov 2017-02-24 1931 }
> 369ea8242c0fb52 Jérôme Glisse 2017-08-31 1932
> ac46d4f3c43241f Jérôme Glisse 2018-12-28 1933 mmu_notifier_invalidate_range_end(&range);
> 369ea8242c0fb52 Jérôme Glisse 2017-08-31 1934
> caed0f486e582ee KOSAKI Motohiro 2009-12-14 1935 return ret;
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1936 }
> ^1da177e4c3f415 Linus Torvalds 2005-04-16 1937
>
> :::::: The code at line 1635 was first introduced by commit
> :::::: 87b8388b6693beaad43d5d3f41534d5e042f9388 mm/vmscan: avoid split lazyfree THP during shrink_folio_list()
>
> :::::: TO: Lance Yang <ioworker0@gmail.com>
> :::::: CC: Andrew Morton <akpm@linux-foundation.org>
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 2+ messages in thread
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