[PATCH 14/17] blk-mq: move the srcu_struct used for quiescing to the tagset

[Sagi Grimberg]

>>>> +
>>>> +    if (set->flags & BLK_MQ_F_BLOCKING) {
>>>> +        set->srcu = kmalloc(sizeof(*set->srcu), GFP_KERNEL);
>>> Memory with contiguous physical addresses is not necessary, maybe it 
>>> is a better choice to use kvmalloc,
>>> because sizeof(*set->srcu) is a little large.
>>> kvmalloc() is more friendly to scenarios where memory is insufficient 
>>> and running for a long time.
>>
>> Huh?
>>
>> (gdb) p sizeof(struct srcu_struct)
>> $1 = 392
> I double recheck it. What I remember in my head is the old version of 
> the size.
> The size of the latest version is the size that you show.
> Change the srcu_node array to a pointer in April 2022.
> The link:
> https://github.com/torvalds/linux/commit/2ec303113d978931ef368886c4c6bc854493e8bf
> 
> Therefore, kvmalloc() is a better choice for older versions.
> For the latest version, static data member or kmalloc() are OK.

We can keep it dynamic allocation IMO.