[kbuild-all] [android-common:android12-5.4 14/27] fs/userfaultfd.c:1519:9: warning: variable 'ioctls_out' set but not used

tree: https://android.googlesource.com/kernel/common android12-5.4 head: 2c6775a89bc167ea4c153db9ffc3b081d34a05b8 commit: b69f713e60d03ae448e5c9fd92e5b0b193dea7be [14/27] BACKPORT: FROMGIT: userfaultfd: add UFFDIO_CONTINUE ioctl config: x86_64-randconfig-c001-20210814 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 62df4df41c939205b2dc0a2a3bfb75b8c1ed74fa) 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 git remote add android-common https://android.googlesource.com/kernel/common git fetch --no-tags android-common android12-5.4 git checkout b69f713e60d03ae448e5c9fd92e5b0b193dea7be # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): __u64 ioctls_out; ^ 1 warning generated. vim +/ioctls_out +1519 fs/userfaultfd.c 1311 1312 static int userfaultfd_register(struct userfaultfd_ctx *ctx, 1313 unsigned long arg) 1314 { 1315 struct mm_struct *mm = ctx->mm; 1316 struct vm_area_struct *vma, *prev, *cur; 1317 int ret; 1318 struct uffdio_register uffdio_register; 1319 struct uffdio_register __user *user_uffdio_register; 1320 unsigned long vm_flags, new_flags; 1321 bool found; 1322 bool basic_ioctls; 1323 unsigned long start, end, vma_end; 1324 1325 user_uffdio_register = (struct uffdio_register __user *) arg; 1326 1327 ret = -EFAULT; 1328 if (copy_from_user(&uffdio_register, user_uffdio_register, 1329 sizeof(uffdio_register)-sizeof(__u64))) 1330 goto out; 1331 1332 ret = -EINVAL; 1333 if (!uffdio_register.mode) 1334 goto out; 1335 if (uffdio_register.mode & ~UFFD_API_REGISTER_MODES) 1336 goto out; 1337 vm_flags = 0; 1338 if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) 1339 vm_flags |= VM_UFFD_MISSING; 1340 if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { 1341 vm_flags |= VM_UFFD_WP; 1342 /* 1343 * FIXME: remove the below error constraint by 1344 * implementing the wprotect tracking mode. 1345 */ 1346 ret = -EINVAL; 1347 goto out; 1348 } 1349 if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR) { 1350 #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR 1351 goto out; 1352 #endif 1353 vm_flags |= VM_UFFD_MINOR; 1354 } 1355 1356 ret = validate_range(mm, &uffdio_register.range.start, 1357 uffdio_register.range.len); 1358 if (ret) 1359 goto out; 1360 1361 start = uffdio_register.range.start; 1362 end = start + uffdio_register.range.len; 1363 1364 ret = -ENOMEM; 1365 if (!mmget_not_zero(mm)) 1366 goto out; 1367 1368 down_write(&mm->mmap_sem); 1369 if (!mmget_still_valid(mm)) 1370 goto out_unlock; 1371 vma = find_vma_prev(mm, start, &prev); 1372 if (!vma) 1373 goto out_unlock; 1374 1375 /* check that there's at least one vma in the range */ 1376 ret = -EINVAL; 1377 if (vma->vm_start >= end) 1378 goto out_unlock; 1379 1380 /* 1381 * If the first vma contains huge pages, make sure start address 1382 * is aligned to huge page size. 1383 */ 1384 if (is_vm_hugetlb_page(vma)) { 1385 unsigned long vma_hpagesize = vma_kernel_pagesize(vma); 1386 1387 if (start & (vma_hpagesize - 1)) 1388 goto out_unlock; 1389 } 1390 1391 /* 1392 * Search for not compatible vmas. 1393 */ 1394 found = false; 1395 basic_ioctls = false; 1396 for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) { 1397 cond_resched(); 1398 1399 BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ 1400 !!(cur->vm_flags & __VM_UFFD_FLAGS)); 1401 1402 /* check not compatible vmas */ 1403 ret = -EINVAL; 1404 if (!vma_can_userfault(cur, vm_flags)) 1405 goto out_unlock; 1406 1407 /* 1408 * UFFDIO_COPY will fill file holes even without 1409 * PROT_WRITE. This check enforces that if this is a 1410 * MAP_SHARED, the process has write permission to the backing 1411 * file. If VM_MAYWRITE is set it also enforces that on a 1412 * MAP_SHARED vma: there is no F_WRITE_SEAL and no further 1413 * F_WRITE_SEAL can be taken until the vma is destroyed. 1414 */ 1415 ret = -EPERM; 1416 if (unlikely(!(cur->vm_flags & VM_MAYWRITE))) 1417 goto out_unlock; 1418 1419 /* 1420 * If this vma contains ending address, and huge pages 1421 * check alignment. 1422 */ 1423 if (is_vm_hugetlb_page(cur) && end <= cur->vm_end && 1424 end > cur->vm_start) { 1425 unsigned long vma_hpagesize = vma_kernel_pagesize(cur); 1426 1427 ret = -EINVAL; 1428 1429 if (end & (vma_hpagesize - 1)) 1430 goto out_unlock; 1431 } 1432 1433 /* 1434 * Check that this vma isn't already owned by a 1435 * different userfaultfd. We can't allow more than one 1436 * userfaultfd to own a single vma simultaneously or we 1437 * wouldn't know which one to deliver the userfaults to. 1438 */ 1439 ret = -EBUSY; 1440 if (cur->vm_userfaultfd_ctx.ctx && 1441 cur->vm_userfaultfd_ctx.ctx != ctx) 1442 goto out_unlock; 1443 1444 /* 1445 * Note vmas containing huge pages 1446 */ 1447 if (is_vm_hugetlb_page(cur)) 1448 basic_ioctls = true; 1449 1450 found = true; 1451 } 1452 BUG_ON(!found); 1453 1454 if (vma->vm_start < start) 1455 prev = vma; 1456 1457 ret = 0; 1458 do { 1459 cond_resched(); 1460 1461 BUG_ON(!vma_can_userfault(vma, vm_flags)); 1462 BUG_ON(vma->vm_userfaultfd_ctx.ctx && 1463 vma->vm_userfaultfd_ctx.ctx != ctx); 1464 WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); 1465 1466 /* 1467 * Nothing to do: this vma is already registered into this 1468 * userfaultfd and with the right tracking mode too. 1469 */ 1470 if (vma->vm_userfaultfd_ctx.ctx == ctx && 1471 (vma->vm_flags & vm_flags) == vm_flags) 1472 goto skip; 1473 1474 if (vma->vm_start > start) 1475 start = vma->vm_start; 1476 vma_end = min(end, vma->vm_end); 1477 1478 new_flags = (vma->vm_flags & ~__VM_UFFD_FLAGS) | vm_flags; 1479 prev = vma_merge(mm, prev, start, vma_end, new_flags, 1480 vma->anon_vma, vma->vm_file, vma->vm_pgoff, 1481 vma_policy(vma), 1482 ((struct vm_userfaultfd_ctx){ ctx }), 1483 vma_get_anon_name(vma)); 1484 if (prev) { 1485 vma = prev; 1486 goto next; 1487 } 1488 if (vma->vm_start < start) { 1489 ret = split_vma(mm, vma, start, 1); 1490 if (ret) 1491 break; 1492 } 1493 if (vma->vm_end > end) { 1494 ret = split_vma(mm, vma, end, 0); 1495 if (ret) 1496 break; 1497 } 1498 next: 1499 /* 1500 * In the vma_merge() successful mprotect-like case 8: 1501 * the next vma was merged into the current one and 1502 * the current one has not been updated yet. 1503 */ 1504 vma->vm_flags = new_flags; 1505 vma->vm_userfaultfd_ctx.ctx = ctx; 1506 1507 if (is_vm_hugetlb_page(vma) && uffd_disable_huge_pmd_share(vma)) 1508 hugetlb_unshare_all_pmds(vma); 1509 1510 skip: 1511 prev = vma; 1512 start = vma->vm_end; 1513 vma = vma->vm_next; 1514 } while (vma && vma->vm_start < end); 1515 out_unlock: 1516 up_write(&mm->mmap_sem); 1517 mmput(mm); 1518 if (!ret) { 1520 1521 ioctls_out = basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : 1522 UFFD_API_RANGE_IOCTLS; 1523 1524 /* CONTINUE ioctl is only supported for MINOR ranges. */ 1525 if (!(uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR)) 1526 ioctls_out &= ~((__u64)1 << _UFFDIO_CONTINUE); 1527 1528 /* 1529 * Now that we scanned all vmas we can already tell 1530 * userland which ioctls methods are guaranteed to 1531 * succeed on this range. 1532 */ 1533 if (put_user(basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : 1534 UFFD_API_RANGE_IOCTLS, 1535 &user_uffdio_register->ioctls)) 1536 ret = -EFAULT; 1537 } 1538 out: 1539 return ret; 1540 } 1541 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org