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

[Steven Rostedt]

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.

Thanks,

-- Steve