On Thu, Sep 28, 2017 at 10:29:55AM +0200, Ingo Molnar wrote: > > * Kirill A. Shutemov <[email protected]> wrote: > > > For boot-time switching between paging modes, we need to be able to > > change STACK_TOP_MAX at runtime. > > > > The change is trivial and it doesn't affect kernel image size. > > > > Signed-off-by: Kirill A. Shutemov <[email protected]> > > --- > > arch/x86/include/asm/processor.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/include/asm/processor.h > > b/arch/x86/include/asm/processor.h > > index 3fa26a61eabc..fa9300ccce1b 100644 > > --- a/arch/x86/include/asm/processor.h > > +++ b/arch/x86/include/asm/processor.h > > @@ -871,7 +871,7 @@ static inline void spin_lock_prefetch(const void *x) > > IA32_PAGE_OFFSET : TASK_SIZE_MAX) > > > > #define STACK_TOP TASK_SIZE_LOW > > -#define STACK_TOP_MAX TASK_SIZE_MAX > > +#define STACK_TOP_MAX (pgtable_l5_enabled ? TASK_SIZE_MAX : > > DEFAULT_MAP_WINDOW) > > While it's only used once in fs/exec.c, why doesn't it affect kernel image > size?
Oh. After closer look the patch is redundant. The STACK_TOP_MAX is already dynamic due to dynamic TASK_SIZE_MAX, so gcc generates exactly the same code before and after the patch. I'll drop it. -- Kirill A. Shutemov
