Re: [PATCH RFC 3/4] mm: percpu: Add generic pcpu_fc_alloc/free funciton

[Kefeng Wang]

On 2021/11/30 6:45, Dennis Zhou wrote:
> On Sun, Nov 21, 2021 at 05:35:56PM +0800, Kefeng Wang wrote:
> > With previous patch, we could add a generic pcpu first chunk
> > allocation and free function to cleanup the duplicated definations
> > on each architecture.
> >
> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > ---
> >   arch/mips/mm/init.c            | 16 +--------
> >   arch/powerpc/kernel/setup_64.c | 51 ++------------------------
> >   arch/sparc/kernel/smp_64.c     | 50 +-------------------------
> >   arch/x86/kernel/setup_percpu.c | 59 +-----------------------------
> >   drivers/base/arch_numa.c       | 19 +---------
> >   include/linux/percpu.h         |  9 +----
> >   mm/percpu.c                    | 66 ++++++++++++++++++----------------
> >   7 files changed, 42 insertions(+), 228 deletions(-)
...
> > diff --git a/include/linux/percpu.h b/include/linux/percpu.h
> > index 41bb54715b0c..d73c97ef4ff4 100644
> > --- a/include/linux/percpu.h
> > +++ b/include/linux/percpu.h
> > @@ -95,9 +95,6 @@ extern const char * const pcpu_fc_names[PCPU_FC_NR];
> >   extern enum pcpu_fc pcpu_chosen_fc;
> >   
> >   typedef int (pcpu_fc_cpu_to_node_fn_t)(int cpu);
> > -typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size, size_t align,
> > -				     pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);
> > -typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
> >   typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
> >   typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
> >   
> > @@ -112,15 +109,11 @@ extern void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
> >   extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
> >   				size_t atom_size,
> >   				pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
> > -				pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn,
> > -				pcpu_fc_alloc_fn_t alloc_fn,
> > -				pcpu_fc_free_fn_t free_fn);
> > +				pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);
> >   #endif
> >   
> >   #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
> >   extern int __init pcpu_page_first_chunk(size_t reserved_size,
> > -				pcpu_fc_alloc_fn_t alloc_fn,
> > -				pcpu_fc_free_fn_t free_fn,
> >   				pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn,
> >   				pcpu_fc_populate_pte_fn_t populate_pte_fn);
> >   #endif
> > diff --git a/mm/percpu.c b/mm/percpu.c
> > index 3f6cf1ff0be2..efaa1cbaf73d 100644
> > --- a/mm/percpu.c
> > +++ b/mm/percpu.c
> > @@ -2992,6 +2992,30 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
> >   
> >   	return ai;
> >   }
> > +
> > +static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align,
> > +				   pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
> > +{
> > +	const unsigned long goal = __pa(MAX_DMA_ADDRESS);
> > +	int node = NUMA_NO_NODE;
> > +	void *ptr;
> > +
> > +	if (cpu_to_nd_fn)
> > +		node = cpu_to_nd_fn(cpu);
> > +
> > +	if (node == NUMA_NO_NODE || !node_online(node) || !NODE_DATA(node)) {
> > +		ptr = memblock_alloc_from(size, align, goal);
> > +	} else {
> > +		ptr = memblock_alloc_try_nid(size, align, goal,
> > +					     MEMBLOCK_ALLOC_ACCESSIBLE, node);
> > +	}
> > +	return ptr;
> > +}
> My preference here would be to keep this identical to the x86
> implementation where we #ifdef CONFIG_NUMA.

I will add back '#ifdef CONFIG_NUMA',  also will add back the 
pr_debug/pr_info part as x86 does,

> Overall this makes sense.
>
> Thanks,
> Dennis
> .