Re: [PATCH v3 6/6] efi: Disable mirror feature if kernelcore is not specified

[Kefeng Wang]

On 2022/6/10 19:20, Ard Biesheuvel wrote:
> On Tue, 7 Jun 2022 at 11:16, Wupeng Ma <mawupeng1@xxxxxxxxxx> wrote:
> > From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
> >
> > If system have some mirrored memory and mirrored feature is not specified
> > in boot parameter, the basic mirrored feature will be enabled and this will
> > lead to the following situations:
> >
> > - memblock memory allocation prefers mirrored region. This may have some
> >    unexpected influence on numa affinity.
> >
> > - contiguous memory will be split into several parts if parts of them
> >    is mirrored memory via memblock_mark_mirror().
> >
> > To fix this, variable mirrored_kernelcore will be checked before calling
> > efi_find_mirror() which will enable basic mirrored feature and this
> > variable is true if kernelcore=mirror is added in the kernel parameters.
> >
> > Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
> This seems like the wrong place to do this. If mirrored memory is
> irrelevant to memblock, it should ignore the attribute. So I think
> this check belongs in mm/memblock.c instead.

Sound good,  let's add check into memblock_mark_mirror() and retain

the efi memory mirror information printing.

> > ---
> >   drivers/firmware/efi/efi.c | 3 +++
> >   include/linux/mm.h         | 2 ++
> >   mm/page_alloc.c            | 2 +-
> >   3 files changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> > index 79c232e07de7..8a5edcb0dd82 100644
> > --- a/drivers/firmware/efi/efi.c
> > +++ b/drivers/firmware/efi/efi.c
> > @@ -454,6 +454,9 @@ void __init efi_find_mirror(void)
> >          if (!efi_enabled(EFI_MEMMAP))
> >                  return;
> >
> > +       if (!mirrored_kernelcore)
> > +               return;
> > +
> >          for_each_efi_memory_desc(md) {
> >                  unsigned long long start = md->phys_addr;
> >                  unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index bc8f326be0ce..741ac7d022c3 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -2540,6 +2540,8 @@ extern void get_pfn_range_for_nid(unsigned int nid,
> >                          unsigned long *start_pfn, unsigned long *end_pfn);
> >   extern unsigned long find_min_pfn_with_active_regions(void);
> >
> > +extern bool mirrored_kernelcore;
> > +
> >   #ifndef CONFIG_NUMA
> >   static inline int early_pfn_to_nid(unsigned long pfn)
> >   {
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index e008a3df0485..cf6f70aba787 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -356,7 +356,7 @@ static unsigned long required_kernelcore_percent __initdata;
> >   static unsigned long required_movablecore __initdata;
> >   static unsigned long required_movablecore_percent __initdata;
> >   static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
> > -static bool mirrored_kernelcore __meminitdata;
> > +bool mirrored_kernelcore __meminitdata;
> >
> >   /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
> >   int movable_zone;
> > --
> > 2.25.1
> .