selftests/mm: fix read_file() return value check

read_file() returns 0 on open/read failures and never returns negative
values.  Existing < 0 error checks never trigger, so read failures are
silently ignored.  Check for zero return to detect read_file() failures.

Also fix misleading error message in get_finfo().  The error string
incorrectly references read_num when reading uevent files.

Link: https://lore.kernel.org/20260807013555.36525-1-hongfu.li@linux.dev
Fixes: e0c13f9761df ("khugepaged: add self test")
Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions