Re: [PATCH] mm/slab: Fix undefined init_cache_node_node() for NUMA and !SMP

[Vlastimil Babka]

On 3/21/23 09:50, Geert Uytterhoeven wrote:
> Hi Adrian,
> 
> On Tue, Mar 21, 2023 at 9:47 AM John Paul Adrian Glaubitz
> <glaubitz@xxxxxxxxxxxxxxxxxxx> wrote:
>> On Tue, 2023-03-21 at 09:30 +0100, Geert Uytterhoeven wrote:
>> > sh/migor_defconfig:
>> >
>> >     mm/slab.c: In function ‘slab_memory_callback’:
>> >     mm/slab.c:1127:23: error: implicit declaration of function ‘init_cache_node_node’; did you mean ‘drain_cache_node_node’? [-Werror=implicit-function-declaration]
>> >      1127 |                 ret = init_cache_node_node(nid);
>> >         |                       ^~~~~~~~~~~~~~~~~~~~
>> >         |                       drain_cache_node_node
>> >
>> > The #ifdef condition protecting the definition of init_cache_node_node()
>> > no longer matches the conditions protecting the (multiple) users.
>> >
>> > Fix this by syncing the conditions.
>> >
>> > Fixes: 76af6a054da40553 ("mm/migrate: add CPU hotplug to demotion #ifdef")
>> > Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
>> > Link: https://lore.kernel.org/r/b5bdea22-ed2f-3187-6efe-0c72330270a4@xxxxxxxxxxxxx
>> > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>> > ---
>> >  mm/slab.c | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/mm/slab.c b/mm/slab.c
>> > index ba454246ee13dd4d..de1523a78f2e7367 100644
>> > --- a/mm/slab.c
>> > +++ b/mm/slab.c
>> > @@ -839,7 +839,7 @@ static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp)
>> >       return 0;
>> >  }
>> >
>> > -#if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP)
>> > +#if defined(CONFIG_NUMA) || defined(CONFIG_SMP)
>> >  /*
>> >   * Allocates and initializes node for a node on each slab cache, used for
>> >   * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
>>
>> FWIW, the other #ifdef starting at drain_cache_node_node() closes with "#endif /* CONFIG_NUMA */",
>> while this #ifdef just ends with "#endif". Just in case you want to make this consistent.
> 
> I guess that's fine, as init_cache_node_node() is a small function.
> #endif comments are typically used when the start and end markers
> do not fit on your (80x25 ;-) screen.

Agreed with this reasoning.

>> Reviewed-by: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
> 
> Thanks!

Applied to slab/for-6.3-rc4/fixes, thanks!

> Gr{oetje,eeting}s,
> 
>                         Geert
>