ftrace: Do not leak a module's empty page group

When every mcount_loc entry of a module is skipped,
ftrace_process_locs() leaves the module's first page group linked
with no records. ftrace_release_mod() matches a module's groups by
records[0].ip, which is 0 here, so the group is never freed. While
it stays linked, ftrace_free_mem() reads pg->records[pg->index - 1]
with pg->index == 0 on every later module load, as lookup_rec() did
before commit ee92fa443358f ("ftrace: Fix invalid address access in
lookup_rec() when index is 0").

Unlink and free the new page groups when none of them got a record.

Link: https://patch.msgid.link/20260924-b4-arm64-callops-kcfi-v2-1-587865b6d991@linux.dev
Reported-by: sashiko-bot@kernel.org
Closes: https://lore.kernel.org/all/20260904013350.5141B1F000E9@smtp.kernel.org/
Assisted-by: LLM
Signed-off-by: Jose Fernandez (Anthropic) <jose.fernandez@linux.dev>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

0 files changed, 0 insertions, 0 deletions