On Wed, Oct 09, 2024 at 06:45:08AM +0800, kernel test robot wrote: > Hi Jann, > > kernel test robot noticed the following build errors: > > [auto build test ERROR on 8cf0b93919e13d1e8d4466eb4080a4c4d9d66d7b] > > url: https://github.com/intel-lab-lkp/linux/commits/Jann-Horn/mm-Enforce-a-minimal-stack-gap-even-against-inaccessible-VMAs/20241008-065733 > base: 8cf0b93919e13d1e8d4466eb4080a4c4d9d66d7b > patch link: https://lore.kernel.org/r/20241008-stack-gap-inaccessible-v1-1-848d4d891f21%40google.com > patch subject: [PATCH] mm: Enforce a minimal stack gap even against inaccessible VMAs > config: parisc-randconfig-r072-20241009 (https://download.01.org/0day-ci/archive/20241009/202410090632.brLG8w0b-lkp@xxxxxxxxx/config) > compiler: hppa-linux-gcc (GCC) 14.1.0 > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241009/202410090632.brLG8w0b-lkp@xxxxxxxxx/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@xxxxxxxxx> > | Closes: https://lore.kernel.org/oe-kbuild-all/202410090632.brLG8w0b-lkp@xxxxxxxxx/ > > All errors (new ones prefixed by >>): > > mm/mmap.c: In function 'expand_upwards': > >> mm/mmap.c:1069:39: error: 'prev' undeclared (first use in this function) > 1069 | if (vma_is_accessible(prev)) Suspect this is just a simple typo and should be next rather than prev :>) > | ^~~~ > mm/mmap.c:1069:39: note: each undeclared identifier is reported only once for each function it appears in > > > vim +/prev +1069 mm/mmap.c > > 1036 > 1037 #if defined(CONFIG_STACK_GROWSUP) > 1038 /* > 1039 * PA-RISC uses this for its stack. > 1040 * vma is the last one with address > vma->vm_end. Have to extend vma. > 1041 */ > 1042 static int expand_upwards(struct vm_area_struct *vma, unsigned long address) > 1043 { > 1044 struct mm_struct *mm = vma->vm_mm; > 1045 struct vm_area_struct *next; > 1046 unsigned long gap_addr; > 1047 int error = 0; > 1048 VMA_ITERATOR(vmi, mm, vma->vm_start); > 1049 > 1050 if (!(vma->vm_flags & VM_GROWSUP)) > 1051 return -EFAULT; > 1052 > 1053 /* Guard against exceeding limits of the address space. */ > 1054 address &= PAGE_MASK; > 1055 if (address >= (TASK_SIZE & PAGE_MASK)) > 1056 return -ENOMEM; > 1057 address += PAGE_SIZE; > 1058 > 1059 /* Enforce stack_guard_gap */ > 1060 gap_addr = address + stack_guard_gap; > 1061 > 1062 /* Guard against overflow */ > 1063 if (gap_addr < address || gap_addr > TASK_SIZE) > 1064 gap_addr = TASK_SIZE; > 1065 > 1066 next = find_vma_intersection(mm, vma->vm_end, gap_addr); > 1067 if (next && !(next->vm_flags & VM_GROWSUP)) { > 1068 /* see comments in expand_downwards() */ > > 1069 if (vma_is_accessible(prev)) > 1070 return -ENOMEM; > 1071 if (address == next->vm_start) > 1072 return -ENOMEM; > 1073 } > 1074 > 1075 if (next) > 1076 vma_iter_prev_range_limit(&vmi, address); > 1077 > 1078 vma_iter_config(&vmi, vma->vm_start, address); > 1079 if (vma_iter_prealloc(&vmi, vma)) > 1080 return -ENOMEM; > 1081 > 1082 /* We must make sure the anon_vma is allocated. */ > 1083 if (unlikely(anon_vma_prepare(vma))) { > 1084 vma_iter_free(&vmi); > 1085 return -ENOMEM; > 1086 } > 1087 > 1088 /* Lock the VMA before expanding to prevent concurrent page faults */ > 1089 vma_start_write(vma); > 1090 /* > 1091 * vma->vm_start/vm_end cannot change under us because the caller > 1092 * is required to hold the mmap_lock in read mode. We need the > 1093 * anon_vma lock to serialize against concurrent expand_stacks. > 1094 */ > 1095 anon_vma_lock_write(vma->anon_vma); > 1096 > 1097 /* Somebody else might have raced and expanded it already */ > 1098 if (address > vma->vm_end) { > 1099 unsigned long size, grow; > 1100 > 1101 size = address - vma->vm_start; > 1102 grow = (address - vma->vm_end) >> PAGE_SHIFT; > 1103 > 1104 error = -ENOMEM; > 1105 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { > 1106 error = acct_stack_growth(vma, size, grow); > 1107 if (!error) { > 1108 /* > 1109 * We only hold a shared mmap_lock lock here, so > 1110 * we need to protect against concurrent vma > 1111 * expansions. anon_vma_lock_write() doesn't > 1112 * help here, as we don't guarantee that all > 1113 * growable vmas in a mm share the same root > 1114 * anon vma. So, we reuse mm->page_table_lock > 1115 * to guard against concurrent vma expansions. > 1116 */ > 1117 spin_lock(&mm->page_table_lock); > 1118 if (vma->vm_flags & VM_LOCKED) > 1119 mm->locked_vm += grow; > 1120 vm_stat_account(mm, vma->vm_flags, grow); > 1121 anon_vma_interval_tree_pre_update_vma(vma); > 1122 vma->vm_end = address; > 1123 /* Overwrite old entry in mtree. */ > 1124 vma_iter_store(&vmi, vma); > 1125 anon_vma_interval_tree_post_update_vma(vma); > 1126 spin_unlock(&mm->page_table_lock); > 1127 > 1128 perf_event_mmap(vma); > 1129 } > 1130 } > 1131 } > 1132 anon_vma_unlock_write(vma->anon_vma); > 1133 vma_iter_free(&vmi); > 1134 validate_mm(mm); > 1135 return error; > 1136 } > 1137 #endif /* CONFIG_STACK_GROWSUP */ > 1138 > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki
