Re: [PATCH net v8 03/15] net: cache snapshot entries for ndo_set_rx_mode_async

[Paolo Abeni <pabeni@redhat.com>]

On 4/21/26 11:52 AM, Paolo Abeni wrote:
> On 4/16/26 8:57 PM, Stanislav Fomichev wrote:
>> Add a per-device netdev_hw_addr_list cache (rx_mode_addr_cache) that
>> allows __hw_addr_list_snapshot() and __hw_addr_list_reconcile() to
>> reuse previously allocated entries instead of hitting GFP_ATOMIC on
>> every snapshot cycle.
>>
>> snapshot pops entries from the cache when available, falling back to
>> __hw_addr_create(). reconcile splices both snapshot lists back into
>> the cache via __hw_addr_splice(). The cache is flushed in
>> free_netdev().
>>
>> Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
>> (cherry picked from commit ba3ab1832a511f660fdc6231245b14bf610c05bd)
> 
> Are you backporting from 7.2 via time machine??? :-P
> 
>> @@ -611,8 +633,8 @@ void __hw_addr_list_reconcile(struct netdev_hw_addr_list *real_list,
>>  		}
>>  	}
>>  
>> -	__hw_addr_flush(work);
>> -	__hw_addr_flush(ref);
>> +	__hw_addr_splice(cache, work);
>> +	__hw_addr_splice(cache, ref);
> 
> I think here sashiko has a point, with the cache size being unbounded. I
> guess syzkaller or the like will find a way to make it grow too much.
> 
> What about hard-limit it to some reasonable value?!?

There are a few more remarks from sashiko at the driver level, but
AFAICS are all pre-existing issues.

I think even the above one it's better handled as a follow-up, so I'm
applying the series as-is (I'll just drop the cherry-pick statement above).

/P