Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting

From: Heiko Carstens
Date: Tue Jan 26 2016 - 13:19:30 EST


On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> We can use debug_pagealloc_enabled() to check if we can map
> the identity mapping with 1MB/2GB pages as well as to print
> the current setting in dump_stack.
>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> arch/s390/kernel/dumpstack.c | 4 +++-
> arch/s390/mm/vmem.c | 10 ++++------
> 2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> index dc8e204..a1c0530 100644
> --- a/arch/s390/kernel/dumpstack.c
> +++ b/arch/s390/kernel/dumpstack.c
> @@ -11,6 +11,7 @@
> #include <linux/export.h>
> #include <linux/kdebug.h>
> #include <linux/ptrace.h>
> +#include <linux/mm.h>
> #include <linux/module.h>
> #include <linux/sched.h>
> #include <asm/processor.h>
> @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> printk("SMP ");
> #endif
> #ifdef CONFIG_DEBUG_PAGEALLOC
> - printk("DEBUG_PAGEALLOC");
> + printk("DEBUG_PAGEALLOC(%s)",
> + debug_pagealloc_enabled() ? "enabled" : "disabled");
> #endif

I'd prefer if you change this to

if (debug_pagealloc_enabled())
printk("DEBUG_PAGEALLOC");

That way we can get rid of yet another ifdef. Having
"DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.