Re: [PATCH] rhashtable: Use irq work for shrinking

[Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>]

On 6/4/26 3:17 AM, Herbert Xu wrote:
> On Wed, Jun 03, 2026 at 02:08:25PM +0100, Mykyta Yatsenko wrote:
>>
>> For v7 I'm dropping automatic_shrinking, because it adds a risk of
>> calling schedule_work() on element deletion path (__rhashtable_remove_fast_one())
>> when hashtable size drops below 30% of the capacity.
> 
> Now that expansion uses irq work I think shrinking should switch
> to that as well.
> 

Makes sense, thanks, I'll include your patch below in this series then.

> ---8<---
> Use irq work for automatic shrinking so that this may be called
> in NMI context.
> 
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> 
> diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
> index ef5230cece36..0693bce6f890 100644
> --- a/include/linux/rhashtable.h
> +++ b/include/linux/rhashtable.h
> @@ -1117,7 +1117,7 @@ static __always_inline int __rhashtable_remove_fast_one(
>  		atomic_dec(&ht->nelems);
>  		if (unlikely(ht->p.automatic_shrinking &&
>  			     rht_shrink_below_30(ht, tbl)))
> -			schedule_work(&ht->run_work);
> +			irq_work_queue(&ht->run_irq_work);
>  		err = 0;
>  	}
>  
> Cheers,