Re: [PATCH] block: setup bounce bio_sets properly

[Jens Axboe <axboe@kernel.dk>]

On 10/21/18 6:17 AM, Ondrej Zary wrote:
> On Friday 19 October 2018 18:35:00 Jens Axboe wrote:
>> On 10/19/18 3:10 AM, Ming Lei wrote:
>>> On Thu, Oct 18, 2018 at 03:24:47PM -0600, Jens Axboe wrote:
>>>> We're only setting up the bounce bio sets if we happen
>>>> to need bouncing for regular HIGHMEM, not if we only need
>>>> it for ISA devices.
>>>>
>>>> Reported-by: Ondrej Zary <linux@rainbow-software.org>
>>>> Tested-by: Ondrej Zary <linux@rainbow-software.org>
>>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>>>
>>>> diff --git a/block/bounce.c b/block/bounce.c
>>>> index b30071ac4ec6..1356a2f4aae2 100644
>>>> --- a/block/bounce.c
>>>> +++ b/block/bounce.c
>>>> @@ -31,6 +31,24 @@
>>>>  static struct bio_set bounce_bio_set, bounce_bio_split;
>>>>  static mempool_t page_pool, isa_page_pool;
>>>>  
>>>> +static void init_bounce_bioset(void)
>>>> +{
>>>> +	static bool bounce_bs_setup;
>>>> +	int ret;
>>>> +
>>>> +	if (bounce_bs_setup)
>>>> +		return;
>>>> +
>>>> +	ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
>>>> +	BUG_ON(ret);
>>>> +	if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE))
>>>> +		BUG_ON(1);
>>>> +
>>>> +	ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0);
>>>> +	BUG_ON(ret);
>>>> +	bounce_bs_setup = true;
>>>
>>> When initcall is run from do_basic_setup(), all CPUs and scheduler have been up,
>>> it is likely that init_emergency_pool() is run when one driver is calling
>>> blk_queue_bounce_limit() to start init_emergency_isa_pool().
>>>
>>> So the above code might be run twice.
>>
>> Good point, it's actually not even safe right now with the mempool
>> setup. How about the below?
>>
>>
>> diff --git a/block/bounce.c b/block/bounce.c
>> index b30071ac4ec6..ec0d99995f5f 100644
>> --- a/block/bounce.c
>> +++ b/block/bounce.c
>> @@ -31,6 +31,24 @@
>>  static struct bio_set bounce_bio_set, bounce_bio_split;
>>  static mempool_t page_pool, isa_page_pool;
>>  
>> +static void init_bounce_bioset(void)
>> +{
>> +	static bool bounce_bs_setup;
>> +	int ret;
>> +
>> +	if (bounce_bs_setup)
>> +		return;
>> +
>> +	ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
>> +	BUG_ON(ret);
>> +	if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE))
>> +		BUG_ON(1);
>> +
>> +	ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0);
>> +	BUG_ON(ret);
>> +	bounce_bs_setup = true;
>> +}
>> +
>>  #if defined(CONFIG_HIGHMEM)
>>  static __init int init_emergency_pool(void)
>>  {
>> @@ -44,14 +62,7 @@ static __init int init_emergency_pool(void)
>>  	BUG_ON(ret);
>>  	pr_info("pool size: %d pages\n", POOL_SIZE);
>>  
>> -	ret = bioset_init(&bounce_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
>> -	BUG_ON(ret);
>> -	if (bioset_integrity_create(&bounce_bio_set, BIO_POOL_SIZE))
>> -		BUG_ON(1);
>> -
>> -	ret = bioset_init(&bounce_bio_split, BIO_POOL_SIZE, 0, 0);
>> -	BUG_ON(ret);
>> -
>> +	init_bounce_bioset();
>>  	return 0;
>>  }
>>  
>> @@ -86,6 +97,8 @@ static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
>>  	return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
>>  }
>>  
>> +static DEFINE_MUTEX(isa_mutex);
>> +
>>  /*
>>   * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
>>   * as the max address, so check if the pool has already been created.
>> @@ -94,14 +107,20 @@ int init_emergency_isa_pool(void)
>>  {
>>  	int ret;
>>  
>> -	if (mempool_initialized(&isa_page_pool))
>> +	mutex_lock(&isa_mutex);
>> +
>> +	if (mempool_initialized(&isa_page_pool)) {
>> +		mutex_unlock(&isa_mutex);
>>  		return 0;
>> +	}
>>  
>>  	ret = mempool_init(&isa_page_pool, ISA_POOL_SIZE, mempool_alloc_pages_isa,
>>  			   mempool_free_pages, (void *) 0);
>>  	BUG_ON(ret);
>>  
>>  	pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);
>> +	init_bounce_bioset();
>> +	mutex_unlock(&isa_mutex);
>>  	return 0;
>>  }
>>  
> 
> Works for me.

Thanks Ondrej, I'm going to queue it up for 4.20 and mark it for stable.

-- 
Jens Axboe