While analyzing

        LTP: madvise11 sometimes fails with madvise(..., MADV_SOFT_OFFLINE) returning -EBUSY

        https://issues.redhat.com/browse/RHEL-9292

I noticed that the test fails whenever the madvise() request to soft offline (MADV_SOFT_OFFLINE) pages receives an eventual -EBUSY. This is not a kernel problem as -EBUSY is a valid value. The problem is that the test stops with a failure report.

The details for the cases where -EBUSY can be returned are described in RHEL-9292.

The error handling in madvise11.c is:

https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/madvise/madvise11.c#L130C1-L136C5

            if (madvise(ptrs[num_alloc], pagesize, MADV_SOFT_OFFLINE) == -1) {
                if (errno != EINVAL)
                    tst_res(TFAIL | TERRNO, "madvise failed");
                if (errno == EINVAL)
                    tst_res(TCONF, "madvise() didn't support MADV_SOFT_OFFLINE");
                return errno;
            } 

As a side note, there is an associated issue that the man-pages for madvise(2) do not mention -EBUSY as a possible return for madvise soft offlining requests. https://issues.redhat.com/browse/RHEL-34105