Re: [PATCH v2] fork: initialize function graph state before copy_exec_state()

[Jérémy Jean]

On 2026-08-22 17:22, Steven Rostedt wrote:
> On Sat, 22 Aug 2026 08:49:27 +0000
> Jérémy Jean <Jeremy.Jean@xxxxxxxxxxxxxxxxx> wrote:
>
> > dup_task_struct() copies the parent's task_struct, including 
> > ret_stack.
> > ftrace_graph_init_task() clears the copied function graph state, but 
> > it
> > currently runs after copy_exec_state().
> >
> > For non-CLONE_VM forks, copy_exec_state() allocates a new 
> > task_exec_state.
> > If that allocation fails, copy_process() reaches bad_fork_free and
> > free_task() calls ftrace_graph_exit_task(). Since the child still 
> > carries
> > the parent's ret_stack pointer, the unwind frees the parent's active
> > function graph return stack. The parent subsequently accesses freed 
> > memory
> > from function_graph_enter_regs().
>
> As this effects function_graph tracing, please resend and Cc:
> linux-trace-kernel@xxxxxxxxxxxxxxx so that it gets to the proper
> patchwork. It will need to go through my tree so that it gets the
> proper testing.

Hello Steve,

Done. Thanks for the feedback.
Let me know if I can help more.

Regards,
Jérémy