tree: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable head: df3ae4347aff9be1e9763ffa3b1015fca348bfbd commit: 92e3612279f925881e96dcc89acfb6bf96a2bb2a [83/143] mm/khugepaged: fix vm_lock/i_mmap_rwsem inversion in retract_page_tables config: i386-randconfig-a002 (https://download.01.org/0day-ci/archive/20230304/202303042159.qPwZsZsh-lkp@xxxxxxxxx/config) compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1) 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://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?id=92e3612279f925881e96dcc89acfb6bf96a2bb2a git remote add akpm-mm https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git git fetch --no-tags akpm-mm mm-unstable git checkout 92e3612279f925881e96dcc89acfb6bf96a2bb2a # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Link: https://lore.kernel.org/oe-kbuild-all/202303042159.qPwZsZsh-lkp@xxxxxxxxx/ All errors (new ones prefixed by >>): >> mm/khugepaged.c:1704:9: error: implicit declaration of function 'vma_try_start_write' is invalid in C99 [-Werror,-Wimplicit-function-declaration] if (!vma_try_start_write(vma)) ^ mm/khugepaged.c:1704:9: note: did you mean 'vma_start_write'? include/linux/mm.h:719:20: note: 'vma_start_write' declared here static inline void vma_start_write(struct vm_area_struct *vma) {} ^ 1 error generated. vim +/vma_try_start_write +1704 mm/khugepaged.c 1641 1642 static int retract_page_tables(struct address_space *mapping, pgoff_t pgoff, 1643 struct mm_struct *target_mm, 1644 unsigned long target_addr, struct page *hpage, 1645 struct collapse_control *cc) 1646 { 1647 struct vm_area_struct *vma; 1648 int target_result = SCAN_FAIL; 1649 1650 i_mmap_lock_write(mapping); 1651 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { 1652 int result = SCAN_FAIL; 1653 struct mm_struct *mm = NULL; 1654 unsigned long addr = 0; 1655 pmd_t *pmd; 1656 bool is_target = false; 1657 1658 /* 1659 * Check vma->anon_vma to exclude MAP_PRIVATE mappings that 1660 * got written to. These VMAs are likely not worth investing 1661 * mmap_write_lock(mm) as PMD-mapping is likely to be split 1662 * later. 1663 * 1664 * Note that vma->anon_vma check is racy: it can be set up after 1665 * the check but before we took mmap_lock by the fault path. 1666 * But page lock would prevent establishing any new ptes of the 1667 * page, so we are safe. 1668 * 1669 * An alternative would be drop the check, but check that page 1670 * table is clear before calling pmdp_collapse_flush() under 1671 * ptl. It has higher chance to recover THP for the VMA, but 1672 * has higher cost too. It would also probably require locking 1673 * the anon_vma. 1674 */ 1675 if (READ_ONCE(vma->anon_vma)) { 1676 result = SCAN_PAGE_ANON; 1677 goto next; 1678 } 1679 addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); 1680 if (addr & ~HPAGE_PMD_MASK || 1681 vma->vm_end < addr + HPAGE_PMD_SIZE) { 1682 result = SCAN_VMA_CHECK; 1683 goto next; 1684 } 1685 mm = vma->vm_mm; 1686 is_target = mm == target_mm && addr == target_addr; 1687 result = find_pmd_or_thp_or_none(mm, addr, &pmd); 1688 if (result != SCAN_SUCCEED) 1689 goto next; 1690 /* 1691 * We need exclusive mmap_lock to retract page table. 1692 * 1693 * We use trylock due to lock inversion: we need to acquire 1694 * mmap_lock while holding page lock. Fault path does it in 1695 * reverse order. Trylock is a way to avoid deadlock. 1696 * 1697 * Also, it's not MADV_COLLAPSE's job to collapse other 1698 * mappings - let khugepaged take care of them later. 1699 */ 1700 result = SCAN_PTE_MAPPED_HUGEPAGE; 1701 if ((cc->is_khugepaged || is_target) && 1702 mmap_write_trylock(mm)) { 1703 /* trylock for the same lock inversion as above */ > 1704 if (!vma_try_start_write(vma)) 1705 goto unlock_next; 1706 1707 /* 1708 * Re-check whether we have an ->anon_vma, because 1709 * collapse_and_free_pmd() requires that either no 1710 * ->anon_vma exists or the anon_vma is locked. 1711 * We already checked ->anon_vma above, but that check 1712 * is racy because ->anon_vma can be populated under the 1713 * mmap lock in read mode. 1714 */ 1715 if (vma->anon_vma) { 1716 result = SCAN_PAGE_ANON; 1717 goto unlock_next; 1718 } 1719 /* 1720 * When a vma is registered with uffd-wp, we can't 1721 * recycle the pmd pgtable because there can be pte 1722 * markers installed. Skip it only, so the rest mm/vma 1723 * can still have the same file mapped hugely, however 1724 * it'll always mapped in small page size for uffd-wp 1725 * registered ranges. 1726 */ 1727 if (hpage_collapse_test_exit(mm)) { 1728 result = SCAN_ANY_PROCESS; 1729 goto unlock_next; 1730 } 1731 if (userfaultfd_wp(vma)) { 1732 result = SCAN_PTE_UFFD_WP; 1733 goto unlock_next; 1734 } 1735 collapse_and_free_pmd(mm, vma, addr, pmd); 1736 if (!cc->is_khugepaged && is_target) 1737 result = set_huge_pmd(vma, addr, pmd, hpage); 1738 else 1739 result = SCAN_SUCCEED; 1740 1741 unlock_next: 1742 mmap_write_unlock(mm); 1743 goto next; 1744 } 1745 /* 1746 * Calling context will handle target mm/addr. Otherwise, let 1747 * khugepaged try again later. 1748 */ 1749 if (!is_target) { 1750 khugepaged_add_pte_mapped_thp(mm, addr); 1751 continue; 1752 } 1753 next: 1754 if (is_target) 1755 target_result = result; 1756 } 1757 i_mmap_unlock_write(mapping); 1758 return target_result; 1759 } 1760 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests
