Re: blktests failures with v6.12-rc1 kernel

[Jens Axboe <axboe@kernel.dk>]

On 10/4/24 7:26 PM, Zhu Yanjun wrote:
> 
> ? 2024/10/5 0:31, Bart Van Assche ??:
>> On 10/4/24 5:40 AM, Zhu Yanjun wrote:
>>> So I add a jiffies (u64) value into the name.
>>
>> I don't think that embedding the value of the jiffies counter in the kmem cache names is sufficient to make cache names unique. That sounds like a fragile approach to me.
> 
> Sorry. I can not get you. Why jiffies counter is not sufficient to
> make cache names unique? And why is it a fragile approach?

1 jiffy is an eternity, what happens if someone calls
kmem_cache_create() twice in that window?

> I read your latest commit. In your commit, the ida is used to make
> cache names unique. It is a good approach if it can fix this problem.

That seems over-engineered. Seems to me that either these things should
share a slab cache (why do they need one each, if they are the same
sized object?!). And if they really do need one, surely something ala:

static atomic_long_t slab_index;

sprintf(slab_name, "foo-%ld", atomic_inc_return(&slab_index));

would be all you need.

-- 
Jens Axboe