Yanfei Xu <yanfei.xu@xxxxxxxxx> writes:
> [Snip]
>
> On 8/30/2024 3:11 PM, Huang, Ying wrote:
>>> Fixes: 823430c8e9d9 ("memory tier: consolidate the initialization of memory tiers")
>>> Signed-off-by: Yanfei Xu<yanfei.xu@xxxxxxxxx>
>>> ---
>>> mm/memory-tiers.c | 1 -
>>> 1 file changed, 1 deletion(-)
>>>
>>> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
>>> index 4775b3a3dabe..dddcd6b38e28 100644
>>> --- a/mm/memory-tiers.c
>>> +++ b/mm/memory-tiers.c
>>> @@ -895,7 +895,6 @@ static int __init memory_tier_init(void)
>>> WARN_ON(!node_demotion);
>>> #endif
>>> - guard(mutex)(&memory_tier_lock);
>>> /*
>>> * For now we can have 4 faster memory tiers with smaller adistance
>>> * than default DRAM tier.
>> Although it's not absolutely necessary, I still think that it's better
>> to just revert the locking change of memory_tier_init() in commit
>> 823430c8e9d9 ("memory tier: consolidate the initialization of memory
>> tiers"). That is, to use mutex_lock/unlock() and exclude
>> hotplug_memory_notifier() from the locked region. Because we will
>> always hold memory_tier_lock when working on memory tier related data
>> structures in this way.
>
> Thanks for pointing out it. Will do it as below in v2.
>
> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
> index 4775b3a3dabe..ba3738b29cc5 100644
> --- a/mm/memory-tiers.c
> +++ b/mm/memory-tiers.c
> @@ -895,13 +895,14 @@ static int __init memory_tier_init(void)
> WARN_ON(!node_demotion);
> #endif
>
> - guard(mutex)(&memory_tier_lock);
> + mutex_lock(&memory_tier_lock);
> /*
> * For now we can have 4 faster memory tiers with smaller adistance
> * than default DRAM tier.
> */
> default_dram_type =
> mt_find_alloc_memory_type(MEMTIER_ADISTANCE_DRAM,
> &default_memory_types);
> + mutex_unlock(&memory_tier_lock);
> if (IS_ERR(default_dram_type))
> panic("%s() failed to allocate default DRAM tier\n",
> __func__);
>
>
LGTM, feel free to add in the future version.
Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
