2024-03-11 13:48:41

by Arnd Bergmann

Subject: Re: [PATCH] fork: Use THREAD_SIZE_ORDER

On Mon, Mar 11, 2024, at 14:44, Geert Uytterhoeven wrote:
> Use the existing THREAD_SIZE_ORDER definition instead of calculating it
> from THREAD_SIZE and PAGE_SIZE.
>
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> ---
> kernel/fork.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 0d944e92a43ffa13..e79fdfe1f0bf4953 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -252,9 +252,9 @@ static int memcg_charge_kernel_stack(struct vm_struct *vm)
> int ret;
> int nr_charged = 0;
>
> - BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
> + BUG_ON(vm->nr_pages != THREAD_SIZE_ORDER);
>

That doesn't look right, THREAD_SIZE_ORDER not the number of
pages but the the log2 of it, right?

I think you want '(1 << THREAD_SIZE_ORDER)', but at that point
it doesn't actually look simpler than the existing code.

Arnd

2024-03-11 14:11:40

by Geert Uytterhoeven

Subject: Re: [PATCH] fork: Use THREAD_SIZE_ORDER

Hi Arnd,

On Mon, Mar 11, 2024 at 2:48 PM Arnd Bergmann <[email protected]> wrote:
> On Mon, Mar 11, 2024, at 14:44, Geert Uytterhoeven wrote:
> > Use the existing THREAD_SIZE_ORDER definition instead of calculating it
> > from THREAD_SIZE and PAGE_SIZE.
> >
> > Signed-off-by: Geert Uytterhoeven <[email protected]>
> > ---
> > kernel/fork.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/fork.c b/kernel/fork.c
> > index 0d944e92a43ffa13..e79fdfe1f0bf4953 100644
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -252,9 +252,9 @@ static int memcg_charge_kernel_stack(struct vm_struct *vm)
> > int ret;
> > int nr_charged = 0;
> >
> > - BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
> > + BUG_ON(vm->nr_pages != THREAD_SIZE_ORDER);
> >
>
> That doesn't look right, THREAD_SIZE_ORDER not the number of
> pages but the the log2 of it, right?
>
> I think you want '(1 << THREAD_SIZE_ORDER)', but at that point
> it doesn't actually look simpler than the existing code.

Thank you for pointing out my silly mistake.

/me hides in a brown paper bag, with a coffee machine.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds