Re: [PATCH v4 07/12] x86/mtrr: allocate mtrr_value array dynamically

[Juergen Gross]

On 20.03.23 13:25, Huang, Kai wrote:
> On Mon, 2023-03-06 at 17:34 +0100, Juergen Gross wrote:
> > The mtrr_value[] array is a static variable, which is used only in a
> > few configurations. Consuming 6kB is ridiculous for this case,
> > especially as the array doesn't need to be that large and it can easily
> > be allocated dynamically.
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > ---
> >   arch/x86/kernel/cpu/mtrr/mtrr.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c
> > index 0c83990501f5..50cd2287b6e1 100644
> > --- a/arch/x86/kernel/cpu/mtrr/mtrr.c
> > +++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
> > @@ -581,7 +581,7 @@ struct mtrr_value {
> >   	unsigned long	lsize;
> >   };
> >   
> > -static struct mtrr_value mtrr_value[MTRR_MAX_VAR_RANGES];
> > +static struct mtrr_value *mtrr_value;
> >   
> >   static int mtrr_save(void)
> >   {
> > @@ -750,6 +750,7 @@ static int __init mtrr_init_finialize(void)
> >   	 * TBD: is there any system with such CPU which supports
> >   	 * suspend/resume? If no, we should remove the code.
> >   	 */
> > +	mtrr_value = kcalloc(num_var_ranges, sizeof(*mtrr_value), GFP_KERNEL);
>
> Theoretically dynamic allocation can fail, although it should not happen as this
> happens during kernel boot and the size is small.  Maybe a WARN()?

Fine with me.


Juergen

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