On Sat, 5 Dec 2020 13:01:36 +0800
Mingzhe Yang <cainiao666999@xxxxxxxxx> wrote:
> Prior to kernel 4.9 the thread_info structure was at the bottom of
> the kernel stack. kernel 4.9 moved it into the task_struct.
>
> See commits c65eacb ("sched/core: Allow putting thread_info into
> task_struct"), 15f4eae ("x86: Move thread_info into task_struct")
> and 883d50f ("scripts/gdb: fix get_thread_info").
>
> Signed-off-by: Mingzhe Yang <cainiao666999@xxxxxxxxx>
> ---
> Documentation/x86/kernel-stacks.rst | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/x86/kernel-stacks.rst b/Documentation/x86/kernel-stacks.rst
> index 6b0bcf0..e9097f3 100644
> --- a/Documentation/x86/kernel-stacks.rst
> +++ b/Documentation/x86/kernel-stacks.rst
> @@ -15,7 +15,8 @@ Like all other architectures, x86_64 has a kernel stack for every
> active thread. These thread stacks are THREAD_SIZE (2*PAGE_SIZE) big.
> These stacks contain useful data as long as a thread is alive or a
> zombie. While the thread is in user space the kernel stack is empty
> -except for the thread_info structure at the bottom.
> +except for the thread_info structure at the bottom (since kernel 4.9,
> +the thread_info structure has been moved into task_struct).
So this has been sitting in my inbox for a bit, sorry. This seems worth
fixing, but is this the correct fix? The documentation should reflect the
current kernel, rather than what once was with a "(it's not actually that
way anymore)" note. Is the kernel stack truly empty now? If so we should
just say that; otherwise say what's lurking there in current kernels.
Thanks,
jon
