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Message-ID: <202408221703.ioeASthY-lkp@intel.com>
Date: Thu, 22 Aug 2024 17:26:58 +0800
From: kernel test robot <lkp@...el.com>
To: Qi Zheng <zhengqi.arch@...edance.com>, david@...hat.com,
hughd@...gle.com, willy@...radead.org, muchun.song@...ux.dev,
vbabka@...nel.org, akpm@...ux-foundation.org, rppt@...nel.org,
vishal.moola@...il.com, peterx@...hat.com, ryan.roberts@....com
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
linuxppc-dev@...ts.ozlabs.org,
Qi Zheng <zhengqi.arch@...edance.com>
Subject: Re: [PATCH 08/14] mm: copy_pte_range() use
pte_offset_map_maywrite_nolock()
Hi Qi,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on powerpc/next powerpc/fixes linus/master v6.11-rc4 next-20240822]
[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#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Qi-Zheng/mm-pgtable-introduce-pte_offset_map_-readonly-maywrite-_nolock/20240821-162312
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/05c311498fc8e7e9b2143c7b5fef6dc624cfc49f.1724226076.git.zhengqi.arch%40bytedance.com
patch subject: [PATCH 08/14] mm: copy_pte_range() use pte_offset_map_maywrite_nolock()
config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240822/202408221703.ioeASthY-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240822/202408221703.ioeASthY-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408221703.ioeASthY-lkp@intel.com/
All warnings (new ones prefixed by >>):
mm/memory.c: In function 'copy_pte_range':
>> mm/memory.c:1086:15: warning: unused variable 'pmdval' [-Wunused-variable]
1086 | pmd_t pmdval;
| ^~~~~~
vim +/pmdval +1086 mm/memory.c
1076
1077 static int
1078 copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1079 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1080 unsigned long end)
1081 {
1082 struct mm_struct *dst_mm = dst_vma->vm_mm;
1083 struct mm_struct *src_mm = src_vma->vm_mm;
1084 pte_t *orig_src_pte, *orig_dst_pte;
1085 pte_t *src_pte, *dst_pte;
> 1086 pmd_t pmdval;
1087 pte_t ptent;
1088 spinlock_t *src_ptl, *dst_ptl;
1089 int progress, max_nr, ret = 0;
1090 int rss[NR_MM_COUNTERS];
1091 swp_entry_t entry = (swp_entry_t){0};
1092 struct folio *prealloc = NULL;
1093 int nr;
1094
1095 again:
1096 progress = 0;
1097 init_rss_vec(rss);
1098
1099 /*
1100 * copy_pmd_range()'s prior pmd_none_or_clear_bad(src_pmd), and the
1101 * error handling here, assume that exclusive mmap_lock on dst and src
1102 * protects anon from unexpected THP transitions; with shmem and file
1103 * protected by mmap_lock-less collapse skipping areas with anon_vma
1104 * (whereas vma_needs_copy() skips areas without anon_vma). A rework
1105 * can remove such assumptions later, but this is good enough for now.
1106 */
1107 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1108 if (!dst_pte) {
1109 ret = -ENOMEM;
1110 goto out;
1111 }
1112 src_pte = pte_offset_map_maywrite_nolock(src_mm, src_pmd, addr, NULL,
1113 &src_ptl);
1114 if (!src_pte) {
1115 pte_unmap_unlock(dst_pte, dst_ptl);
1116 /* ret == 0 */
1117 goto out;
1118 }
1119 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1120 orig_src_pte = src_pte;
1121 orig_dst_pte = dst_pte;
1122 arch_enter_lazy_mmu_mode();
1123
1124 do {
1125 nr = 1;
1126
1127 /*
1128 * We are holding two locks at this point - either of them
1129 * could generate latencies in another task on another CPU.
1130 */
1131 if (progress >= 32) {
1132 progress = 0;
1133 if (need_resched() ||
1134 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1135 break;
1136 }
1137 ptent = ptep_get(src_pte);
1138 if (pte_none(ptent)) {
1139 progress++;
1140 continue;
1141 }
1142 if (unlikely(!pte_present(ptent))) {
1143 ret = copy_nonpresent_pte(dst_mm, src_mm,
1144 dst_pte, src_pte,
1145 dst_vma, src_vma,
1146 addr, rss);
1147 if (ret == -EIO) {
1148 entry = pte_to_swp_entry(ptep_get(src_pte));
1149 break;
1150 } else if (ret == -EBUSY) {
1151 break;
1152 } else if (!ret) {
1153 progress += 8;
1154 continue;
1155 }
1156 ptent = ptep_get(src_pte);
1157 VM_WARN_ON_ONCE(!pte_present(ptent));
1158
1159 /*
1160 * Device exclusive entry restored, continue by copying
1161 * the now present pte.
1162 */
1163 WARN_ON_ONCE(ret != -ENOENT);
1164 }
1165 /* copy_present_ptes() will clear `*prealloc' if consumed */
1166 max_nr = (end - addr) / PAGE_SIZE;
1167 ret = copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte,
1168 ptent, addr, max_nr, rss, &prealloc);
1169 /*
1170 * If we need a pre-allocated page for this pte, drop the
1171 * locks, allocate, and try again.
1172 */
1173 if (unlikely(ret == -EAGAIN))
1174 break;
1175 if (unlikely(prealloc)) {
1176 /*
1177 * pre-alloc page cannot be reused by next time so as
1178 * to strictly follow mempolicy (e.g., alloc_page_vma()
1179 * will allocate page according to address). This
1180 * could only happen if one pinned pte changed.
1181 */
1182 folio_put(prealloc);
1183 prealloc = NULL;
1184 }
1185 nr = ret;
1186 progress += 8 * nr;
1187 } while (dst_pte += nr, src_pte += nr, addr += PAGE_SIZE * nr,
1188 addr != end);
1189
1190 arch_leave_lazy_mmu_mode();
1191 pte_unmap_unlock(orig_src_pte, src_ptl);
1192 add_mm_rss_vec(dst_mm, rss);
1193 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1194 cond_resched();
1195
1196 if (ret == -EIO) {
1197 VM_WARN_ON_ONCE(!entry.val);
1198 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1199 ret = -ENOMEM;
1200 goto out;
1201 }
1202 entry.val = 0;
1203 } else if (ret == -EBUSY) {
1204 goto out;
1205 } else if (ret == -EAGAIN) {
1206 prealloc = folio_prealloc(src_mm, src_vma, addr, false);
1207 if (!prealloc)
1208 return -ENOMEM;
1209 } else if (ret < 0) {
1210 VM_WARN_ON_ONCE(1);
1211 }
1212
1213 /* We've captured and resolved the error. Reset, try again. */
1214 ret = 0;
1215
1216 if (addr != end)
1217 goto again;
1218 out:
1219 if (unlikely(prealloc))
1220 folio_put(prealloc);
1221 return ret;
1222 }
1223
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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