Hi Peter, Thank you for the patch! Yet something to improve: [auto build test ERROR on hnaz-mm/master] [cannot apply to arnd-asm-generic/master linus/master linux/master v5.18-rc1 next-20220406] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/intel-lab-lkp/linux/commits/Peter-Xu/userfaultfd-wp-Support-shmem-and-hugetlbfs/20220405-100136 base: https://github.com/hnaz/linux-mm master config: s390-randconfig-r044-20220406 (https://download.01.org/0day-ci/archive/20220406/202204062154.2txNJyaf-lkp@xxxxxxxxx/config) compiler: s390-linux-gcc (GCC) 11.2.0 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://github.com/intel-lab-lkp/linux/commit/e7e7aaec811e2817cd169f0cc1d8f81bdf1f05c3 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Peter-Xu/userfaultfd-wp-Support-shmem-and-hugetlbfs/20220405-100136 git checkout e7e7aaec811e2817cd169f0cc1d8f81bdf1f05c3 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=s390 SHELL=/bin/bash If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All errors (new ones prefixed by >>): mm/hugetlb.c: In function 'hugetlb_fault': >> mm/hugetlb.c:5678:13: error: implicit declaration of function 'huge_pte_none_mostly'; did you mean 'pte_none_mostly'? [-Werror=implicit-function-declaration] 5678 | if (huge_pte_none_mostly(entry)) { | ^~~~~~~~~~~~~~~~~~~~ | pte_none_mostly cc1: some warnings being treated as errors vim +5678 mm/hugetlb.c 5616 5617 vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 5618 unsigned long address, unsigned int flags) 5619 { 5620 pte_t *ptep, entry; 5621 spinlock_t *ptl; 5622 vm_fault_t ret; 5623 u32 hash; 5624 pgoff_t idx; 5625 struct page *page = NULL; 5626 struct page *pagecache_page = NULL; 5627 struct hstate *h = hstate_vma(vma); 5628 struct address_space *mapping; 5629 int need_wait_lock = 0; 5630 unsigned long haddr = address & huge_page_mask(h); 5631 5632 ptep = huge_pte_offset(mm, haddr, huge_page_size(h)); 5633 if (ptep) { 5634 /* 5635 * Since we hold no locks, ptep could be stale. That is 5636 * OK as we are only making decisions based on content and 5637 * not actually modifying content here. 5638 */ 5639 entry = huge_ptep_get(ptep); 5640 if (unlikely(is_hugetlb_entry_migration(entry))) { 5641 migration_entry_wait_huge(vma, mm, ptep); 5642 return 0; 5643 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) 5644 return VM_FAULT_HWPOISON_LARGE | 5645 VM_FAULT_SET_HINDEX(hstate_index(h)); 5646 } 5647 5648 /* 5649 * Acquire i_mmap_rwsem before calling huge_pte_alloc and hold 5650 * until finished with ptep. This serves two purposes: 5651 * 1) It prevents huge_pmd_unshare from being called elsewhere 5652 * and making the ptep no longer valid. 5653 * 2) It synchronizes us with i_size modifications during truncation. 5654 * 5655 * ptep could have already be assigned via huge_pte_offset. That 5656 * is OK, as huge_pte_alloc will return the same value unless 5657 * something has changed. 5658 */ 5659 mapping = vma->vm_file->f_mapping; 5660 i_mmap_lock_read(mapping); 5661 ptep = huge_pte_alloc(mm, vma, haddr, huge_page_size(h)); 5662 if (!ptep) { 5663 i_mmap_unlock_read(mapping); 5664 return VM_FAULT_OOM; 5665 } 5666 5667 /* 5668 * Serialize hugepage allocation and instantiation, so that we don't 5669 * get spurious allocation failures if two CPUs race to instantiate 5670 * the same page in the page cache. 5671 */ 5672 idx = vma_hugecache_offset(h, vma, haddr); 5673 hash = hugetlb_fault_mutex_hash(mapping, idx); 5674 mutex_lock(&hugetlb_fault_mutex_table[hash]); 5675 5676 entry = huge_ptep_get(ptep); 5677 /* PTE markers should be handled the same way as none pte */ > 5678 if (huge_pte_none_mostly(entry)) { 5679 ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, 5680 entry, flags); 5681 goto out_mutex; 5682 } 5683 5684 ret = 0; 5685 5686 /* 5687 * entry could be a migration/hwpoison entry at this point, so this 5688 * check prevents the kernel from going below assuming that we have 5689 * an active hugepage in pagecache. This goto expects the 2nd page 5690 * fault, and is_hugetlb_entry_(migration|hwpoisoned) check will 5691 * properly handle it. 5692 */ 5693 if (!pte_present(entry)) 5694 goto out_mutex; 5695 5696 /* 5697 * If we are going to COW/unshare the mapping later, we examine the 5698 * pending reservations for this page now. This will ensure that any 5699 * allocations necessary to record that reservation occur outside the 5700 * spinlock. For private mappings, we also lookup the pagecache 5701 * page now as it is used to determine if a reservation has been 5702 * consumed. 5703 */ 5704 if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) && 5705 !huge_pte_write(entry)) { 5706 if (vma_needs_reservation(h, vma, haddr) < 0) { 5707 ret = VM_FAULT_OOM; 5708 goto out_mutex; 5709 } 5710 /* Just decrements count, does not deallocate */ 5711 vma_end_reservation(h, vma, haddr); 5712 5713 if (!(vma->vm_flags & VM_MAYSHARE)) 5714 pagecache_page = hugetlbfs_pagecache_page(h, 5715 vma, haddr); 5716 } 5717 5718 ptl = huge_pte_lock(h, mm, ptep); 5719 5720 /* Check for a racing update before calling hugetlb_wp() */ 5721 if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) 5722 goto out_ptl; 5723 5724 /* Handle userfault-wp first, before trying to lock more pages */ 5725 if (userfaultfd_wp(vma) && huge_pte_uffd_wp(huge_ptep_get(ptep)) && 5726 (flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) { 5727 struct vm_fault vmf = { 5728 .vma = vma, 5729 .address = haddr, 5730 .real_address = address, 5731 .flags = flags, 5732 }; 5733 5734 spin_unlock(ptl); 5735 if (pagecache_page) { 5736 unlock_page(pagecache_page); 5737 put_page(pagecache_page); 5738 } 5739 mutex_unlock(&hugetlb_fault_mutex_table[hash]); 5740 i_mmap_unlock_read(mapping); 5741 return handle_userfault(&vmf, VM_UFFD_WP); 5742 } 5743 5744 /* 5745 * hugetlb_wp() requires page locks of pte_page(entry) and 5746 * pagecache_page, so here we need take the former one 5747 * when page != pagecache_page or !pagecache_page. 5748 */ 5749 page = pte_page(entry); 5750 if (page != pagecache_page) 5751 if (!trylock_page(page)) { 5752 need_wait_lock = 1; 5753 goto out_ptl; 5754 } 5755 5756 get_page(page); 5757 5758 if (flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) { 5759 if (!huge_pte_write(entry)) { 5760 ret = hugetlb_wp(mm, vma, address, ptep, flags, 5761 pagecache_page, ptl); 5762 goto out_put_page; 5763 } else if (likely(flags & FAULT_FLAG_WRITE)) { 5764 entry = huge_pte_mkdirty(entry); 5765 } 5766 } 5767 entry = pte_mkyoung(entry); 5768 if (huge_ptep_set_access_flags(vma, haddr, ptep, entry, 5769 flags & FAULT_FLAG_WRITE)) 5770 update_mmu_cache(vma, haddr, ptep); 5771 out_put_page: 5772 if (page != pagecache_page) 5773 unlock_page(page); 5774 put_page(page); 5775 out_ptl: 5776 spin_unlock(ptl); 5777 5778 if (pagecache_page) { 5779 unlock_page(pagecache_page); 5780 put_page(pagecache_page); 5781 } 5782 out_mutex: 5783 mutex_unlock(&hugetlb_fault_mutex_table[hash]); 5784 i_mmap_unlock_read(mapping); 5785 /* 5786 * Generally it's safe to hold refcount during waiting page lock. But 5787 * here we just wait to defer the next page fault to avoid busy loop and 5788 * the page is not used after unlocked before returning from the current 5789 * page fault. So we are safe from accessing freed page, even if we wait 5790 * here without taking refcount. 5791 */ 5792 if (need_wait_lock) 5793 wait_on_page_locked(page); 5794 return ret; 5795 } 5796 -- 0-DAY CI Kernel Test Service https://01.org/lkp
