Regressions were observed while testing LTP syscalls cachestat01 and other related tests on the next-20250702 Linux kernel across several devices.

The issue appears to be related to the inability to configure /dev/loop0 via the LOOP_SET_STATUS ioctl, which returned EOPNOTSUPP (Operation not supported). This results in a TBROK condition, causing the test to fail.

Test environments: - arm64 - qemu-x86_64 - qemu-riscv

Regression Analysis: - New regression? Yes - Reproducibility? Yes

Regressions started from next-20250702 ( next-20250708) Good: next-20250701 Bad: next-20250702

Test regression: Linux next-20250702 TWARN ioctl(/dev/loop0, LOOP_SET_STATUS, test_dev.img) failed EOPNOTSUPP (95) TBROK Failed to acquire device

Reported-by: Linux Kernel Functional Testing lkft@linaro.org

## Test log tst_buffers.c:57: TINFO: Test is using guarded buffers tst_tmpdir.c:316: TINFO: Using /tmp/LTP_cacQ9AfS0 as tmpdir (tmpfs filesystem) tst_device.c:98: TINFO: Found free device 0 '/dev/loop0' tst_device.c:190: TWARN: ioctl(/dev/loop0, LOOP_SET_STATUS, test_dev.img) failed: EOPNOTSUPP (95) tst_device.c:362: TBROK: Failed to acquire device

## Source * Kernel version: 6.16.0-rc4-next-20250702 * Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git * Git sha: 50c8770a42faf8b1c7abe93e7c114337f580a97d * Git describe: next-20250702 * Project: https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20250704/tes... * Architectures: arm64, x86_64, riscv64. * Toolchains: gcc-13 and clang-20 * Kconfigs: defconfig+ltp

## Build * Test log: https://qa-reports.linaro.org/api/testruns/28986655/log_file/ * Test details: https://regressions.linaro.org/lkft/linux-next-master/next-20250702/ltp-sysc... * Test history: https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20250704/tes... * Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/2zJjY2EmRMul6P0UgjdOm... * Kernel config: https://storage.tuxsuite.com/public/linaro/lkft/builds/2zJjY2EmRMul6P0UgjdOm...

## List of tests - cachestat01 - cachestat04 - chdir01 - chmod09 - close_range01 - copy_file_range01 - copy_file_range02 - creat09 - fallocate04 - fallocate05 - fallocate06 - fanotify01 - fanotify05 - fanotify06 - fanotify10 - fanotify13 - fanotify14 - fanotify15 - fanotify16 - fanotify17 - fanotify18 - fanotify19 - fanotify20 - fanotify21 - fanotify22 - fanotify23 - fchmodat2_01 - fdatasync03 - fgetxattr01 - fremovexattr01 - fremovexattr02 - fsetxattr01 - fsmount01 - fsmount02 - fsopen01 - fsopen02 - fspick01 - fspick02 - fsskipig01 - fsskipig02 - fsskipig03 - fstatfs01 - fstatfs01_64 - fsync01 - fsync04 - getdents01 - getdents02 - getxattr02 - getxattr03 - inotify03 - ioctl04 - ioctl05 - ioctl06 - ioctl_ficlone02 - ioctl_fiemap01 - ioctl_loop01 - lchown03 - linkat02 - listmount01 - listmount02 - lremovexattr01 - lstat03 - lstat03_64 - mkdir09 - mknodat02 - mmap16 - mount01 - mount02 - mount03 - mount04 - mount05 - mount06 - mount07 - mount_setattr01 - move_mount01 - move_mount02 - msync04 - open_tree01 - open_tree02 - prctl06 - preadv03 - preadv03_64 - preadv203 - preadv203_64 - pwritev03 - pwritev03_64 - quotactl01 - quotactl04 - quotactl06 - quotactl08 - quotactl09 - readahead02 - readdir01 - rename01 - rename03 - rename04 - rename05 - rename06 - rename07 - rename08 - rename10 - rename11 - rename12 - rename13 - rename15 - renameat01 - setxattr01 - stat04 - stat04_64 - statfs01 - statfs01_64 - statmount01 - statmount02 - statmount04 - statmount05 - statmount06 - statmount07 - statvfs01 - statx06 - statx08 - statx10 - statx11 - statx12 - sync01 - syncfs01 - umount01 - umount02 - umount03 - umount2_01 - umount2_02 - unlink09 - utime01 - utime02 - utime03 - utime04 - utime05 - utimensat01 - writev03

-- Linaro LKFT https://lkft.linaro.org