Re: [PATCH 6.10 000/809] 6.10.3-rc3 review

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, Aug 07 2024 at 18:07, Guenter Roeck wrote:
> On 8/6/24 16:24, Thomas Gleixner wrote:
> diff --git a/mm/slub.c b/mm/slub.c
> index 4927edec6a8c..b8a33966d858 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1385,6 +1385,9 @@ static int check_slab(struct kmem_cache *s, struct slab *slab)
>          }
>
>          maxobj = order_objects(slab_order(slab), s->size);
> +
> +       pr_info_once("##### slab->objects=%u maxobj=%u\n", slab->objects, maxobj);
> +
>          if (slab->objects > maxobj) {
>                  slab_err(s, slab, "objects %u > max %u",
>                          slab->objects, maxobj);
>
> results in:
>
> ##### slab->objects=21 maxobj=21
> =============================================================================
> BUG kmem_cache_node (Not tainted): objects 21 > max 16

Careful vs. the pr_once(). It's not necessarily the first allocation
which trips up. I removed slab_err() in that condition and just printed
the data:

[    0.000000] Order: 1 Size:  384 Nobj: 21 Maxobj: 16 21 Inuse: 14
[    0.000000] Order: 0 Size:  168 Nobj: 24 Maxobj: 16 24 Inuse:  1
[    0.000000] Order: 1 Size:  320 Nobj: 25 Maxobj: 16 25 Inuse: 18
[    0.000000] Order: 1 Size:  320 Nobj: 25 Maxobj: 16 25 Inuse: 19
[    0.000000] Order: 1 Size:  320 Nobj: 25 Maxobj: 16 25 Inuse: 20
[    0.000000] Order: 0 Size:  160 Nobj: 25 Maxobj: 16 25 Inuse:  5
[    0.000000] Order: 2 Size:  672 Nobj: 24 Maxobj: 16 24 Inuse:  1
[    0.000000] Order: 3 Size: 1536 Nobj: 21 Maxobj: 16 21 Inuse:  1
[    0.000000] Order: 3 Size: 1536 Nobj: 21 Maxobj: 16 21 Inuse:  2
[    0.000000] Order: 3 Size: 1536 Nobj: 21 Maxobj: 16 21 Inuse: 10

The maxobj column shows the failed result and the result from the second
invocation inside of the printk().

Let's wait for PARISC people to run it on actual hardware.

Thanks,

        tglx