On Wed, Jul 9, 2025, at 15:48, Naresh Kamboju wrote:
On Tue, 8 Jul 2025 at 18:28, Naresh Kamboju naresh.kamboju@linaro.org wrote:
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.
Anders, bisected this down to this commit id, # first bad commit: [9eb22f7fedfc9eb1b7f431a5359abd4d15b0b0cd] fs: add ioctl to query metadata and protection info capabilities
I see the problem now in
+ if (_IOC_NR(cmd) == _IOC_NR(FS_IOC_GETLBMD_CAP)) + return blk_get_meta_cap(bdev, cmd, argp); +
This only compares _IOC_NR() but not _IOC_TYPE, so LOOP_SET_STATUS is treated the same as FS_IOC_GETLBMD_CAP, since both use '2' in the lower 8 bit.
include/uapi/linux/fs.h:#define FS_IOC_GETLBMD_CAP _IOWR(0x15, 2, struct logical_block_metadata_cap) include/uapi/linux/loop.h:#define LOOP_SET_STATUS 0x4C02
I checked a couple of other drivers using _IOC_NR(), and it seems that they many of them have the same bug, e.g.:
drivers/accel/habanalabs/common/habanalabs_ioctl.c drivers/block/ublk_drv.c drivers/dma-buf/dma-heap.c
Arnd