From: David Carlier <devnexen@gmail.com> stable inclusion from stable-v6.6.140 commit 247ed8a969f981bfba3112fd4bb441eaa6cef59c category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9232 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit fad217e16fded7f3c09f8637b0f6a224d58b5f2e ] When a tracepoint goes through the 0 -> 1 transition, tracepoint_add_func() invokes the subsystem's ext->regfunc() before attempting to install the new probe via func_add(). If func_add() then fails (for example, when allocate_probes() cannot allocate a new probe array under memory pressure and returns -ENOMEM), the function returns the error without calling the matching ext->unregfunc(), leaving the side effects of regfunc() behind with no installed probe to justify them. For syscall tracepoints this is particularly unpleasant: syscall_regfunc() bumps sys_tracepoint_refcount and sets SYSCALL_TRACEPOINT on every task. After a leaked failure, the refcount is stuck at a non-zero value with no consumer, and every task continues paying the syscall trace entry/exit overhead until reboot. Other subsystems providing regfunc()/unregfunc() pairs exhibit similarly scoped persistent state. Mirror the existing 1 -> 0 cleanup and call ext->unregfunc() in the func_add() error path, gated on the same condition used there so the unwind is symmetric with the registration. Fixes: 8cf868affdc4 ("tracing: Have the reg function allow to fail") Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://patch.msgid.link/20260413190601.21993-1-devnexen@gmail.com Signed-off-by: David Carlier <devnexen@gmail.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> [ changed `tp->ext->unregfunc` to `tp->unregfunc` to match older struct layout ] Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Tengda Wu <wutengda2@huawei.com> --- kernel/tracepoint.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 8d1507dd0724..f7a4210d5d5e 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -337,6 +337,8 @@ static int tracepoint_add_func(struct tracepoint *tp, lockdep_is_held(&tracepoints_mutex)); old = func_add(&tp_funcs, func, prio); if (IS_ERR(old)) { + if (tp->unregfunc && !static_key_enabled(&tp->key)) + tp->unregfunc(); WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM); return PTR_ERR(old); } -- 2.34.1