Re: [PATCH] LoongArch: Remove unused code to avoid build warning

[Huacai Chen]

On Mon, May 18, 2026 at 9:42 AM Guo Ren <guoren@xxxxxxxxxx> wrote:
>
>
>
> On Sun, May 17, 2026 at 5:25 PM Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
> >
> > After commit feee6b2989165631b1 ("mm/memory_hotplug: shrink zones when
> > offlining memory"), __remove_pages() doesn't need the "zone" parameter
> > so the "page" variable is also unused. Remove the unused code to avoid
> > such build warning:
> >
> > arch/loongarch/mm/init.c: In function 'arch_remove_memory':
> > arch/loongarch/mm/init.c:134:22: warning: variable 'page' set but not used [-Wunused-but-set-variable=]
> >   134 |         struct page *page = pfn_to_page(start_pfn);
> >
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> > ---
> >  arch/loongarch/mm/init.c | 4 ----
> >  1 file changed, 4 deletions(-)
> >
> > diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
> > index 3f9ab54114c5..031b39eb081c 100644
> > --- a/arch/loongarch/mm/init.c
> > +++ b/arch/loongarch/mm/init.c
> > @@ -123,11 +123,7 @@ void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
> >  {
> >         unsigned long start_pfn = start >> PAGE_SHIFT;
> >         unsigned long nr_pages = size >> PAGE_SHIFT;
> > -       struct page *page = pfn_to_page(start_pfn);
> >
> > -       /* With altmap the first mapped page is offset from @start */
> > -       if (altmap)
> > -               page += vmem_altmap_offset(altmap);
> >         __remove_pages(start_pfn, nr_pages, altmap);
>
> Good cleanup, but does LoongArch forget to remove the linear mapping? If the memory is unplugged, the mapping is still there. How does the core fetch data from there?
LoongArch's linear mapping is based on DMW rather than TLB, so
removing linear mapping is unnecessary.


Huacai
>
> --
>
> Best Regards
>
>   GUO Ren