On Wed, Jan 19, 2022 at 2:03 PM Axel Rasmussen <axelrasmussen@xxxxxxxxxx> wrote: > > On Wed, Jan 19, 2022 at 1:19 PM Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > > > > On Wed, Jan 19, 2022 at 12:39 PM Axel Rasmussen > > <axelrasmussen@xxxxxxxxxx> wrote: > > > > > > Lokesh, I only spent a few moments looking, but my suspicion is that > > > this is the result of an incomplete backport of these patches to the > > > Android kernel? > > > > > > The UFFDIO_CONTINUE patches introduced ioctls_out since the > > > computation of it got more complicated, and those same patches also > > > modified the put_user() on line 1533 here to use ioctls_out. I think > > > Android backported the first part, but left out the second? > > > > The backport https://android-review.googlesource.com/c/kernel/common/+/1652718 > > looks like a mixture of > > 14819305e09fe4 ("userfaultfd: wp: declare _UFFDIO_WRITEPROTECT > > conditionally") and f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE > > ioctl"). > > Not sure why it was done this way, maybe to minimize code changes > > while backporting. > > Simplest fix is probably to add __maybe_unused to ioctls_out declaration. > > Unfortunately, that doesn't quite do it. That would fix the warning, > but the code in the original e-mail is still wrong: we incorrectly > don't report the _UFFDIO_CONTINUE bit, unless we use the value we > computed in ioctls_out. Apologies for the screw up. Actually, since 5.4 kernel didn't already have UFFD_WRITE_PROTECT feature and neither was I interested in it, so I attempted to only backport UFFDIO_CONTINUE feature and there mistakenly missed this one out. Axel, wouldn't doing what Peter did in the following patch the right thing to do? https://lore.kernel.org/lkml/20200220163112.11409-18-peterx@xxxxxxxxxx/ Basically: - if (put_user(basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : - UFFD_API_RANGE_IOCTLS, - &user_uffdio_register->ioctls)) + if (put_user(ioctls_out, &user_uffdio_register->ioctls)) > > > > > > > > > On Sun, Jan 16, 2022 at 10:11 AM kernel test robot <lkp@xxxxxxxxx> wrote: > > > > > > > > Hi Axel, > > > > > > > > FYI, the error/warning still remains. > > > > > > > > tree: https://github.com/ammarfaizi2/linux-block google/android/kernel/common/android12-5.4 > > > > head: bdf17ba628090156b539b1474eb5c636eeaf571b > > > > commit: b69f713e60d03ae448e5c9fd92e5b0b193dea7be [6517/9999] BACKPORT: FROMGIT: userfaultfd: add UFFDIO_CONTINUE ioctl > > > > config: x86_64-randconfig-a012 (https://download.01.org/0day-ci/archive/20220117/202201170247.Cir3moOM-lkp@xxxxxxxxx/config) > > > > compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c63a3175c2947e8c1a2d3bbe16a8586600705c54) > > > > 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/ammarfaizi2/linux-block/commit/b69f713e60d03ae448e5c9fd92e5b0b193dea7be > > > > git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block > > > > git fetch --no-tags ammarfaizi2-block google/android/kernel/common/android12-5.4 > > > > git checkout b69f713e60d03ae448e5c9fd92e5b0b193dea7be > > > > # save the config file to linux build tree > > > > mkdir build_dir > > > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash > > > > > > > > If you fix the issue, kindly add following tag as appropriate > > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > >> fs/userfaultfd.c:1519:9: warning: variable 'ioctls_out' set but not used [-Wunused-but-set-variable] > > > > __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) { > > > > > 1519 __u64 ioctls_out; > > > > 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@xxxxxxxxxxxx > > >
