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Date:   Thu, 1 Sep 2022 16:43:40 +0800
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Subject: Re: [PATCH 2/3] memblock test: Add test to memblock_reserve() 129th
 region
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To:     Mike Rapoport <rppt@kernel.org>
CC:     Karolina Drobnik <karolinadrobnik@gmail.com>,
        Rebecca Mckeever <remckee0@gmail.com>,
        David Hildenbrand <david@redhat.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
References: <20220830014925.162718-1-shaoqin.huang@intel.com>
 <20220830014925.162718-3-shaoqin.huang@intel.com>
 <YxBogSb3qDMoXcrc@kernel.org>
From:   "Huang, Shaoqin" <shaoqin.huang@intel.com>
In-Reply-To: <YxBogSb3qDMoXcrc@kernel.org>
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On 9/1/2022 4:08 PM, Mike Rapoport wrote:
> On Tue, Aug 30, 2022 at 09:49:18AM +0800, shaoqin.huang@intel.com wrote:
>> From: Shaoqin Huang <shaoqin.huang@intel.com>
>>
>> Reserve 129th region in the memblock, and this will trigger the
>> memblock_double_array() function, this needs valid memory regions. So
>> using dummy_physical_memory_init() to allocate a valid memory region.
>> At the same time, reserve 128 faked memory region, and make sure these
>> reserved region not intersect with the valid memory region. So
>> memblock_double_array() will choose the valid memory region, and it will
>> success.
>>
>> Also need to restore the reserved.regions after memblock_double_array(),
>> to make sure the subsequent tests can run as normal.
>>
>> Signed-off-by: Shaoqin Huang <shaoqin.huang@intel.com>
>> ---
>>   tools/testing/memblock/tests/basic_api.c | 87 ++++++++++++++++++++++++
>>   1 file changed, 87 insertions(+)
>>
>> diff --git a/tools/testing/memblock/tests/basic_api.c b/tools/testing/memblock/tests/basic_api.c
>> index c8e201156cdc..d8defc9866cb 100644
>> --- a/tools/testing/memblock/tests/basic_api.c
>> +++ b/tools/testing/memblock/tests/basic_api.c
>> @@ -686,6 +686,92 @@ static int memblock_reserve_twice_check(void)
>>   	return 0;
>>   }
>>   
>> +/*
>> + * A test that tries to reserve the 129th memory block.
>> + * Expect to trigger memblock_double_array() to double the
>> + * memblock.memory.max, find a new valid memory as
>> + * reserved.regions.
>> + */
>> +static int memblock_reserve_many_check(void)
>> +{
>> +	int i;
>> +	void *orig_region;
>> +	struct region r = {
>> +		.base = SZ_16K,
>> +		.size = MEM_SIZE,
>> +	};
>> +	phys_addr_t memory_base = SZ_128K;
>> +	phys_addr_t new_reserved_regions_size;
>> +
>> +	PREFIX_PUSH();
>> +
>> +	reset_memblock_regions();
>> +	memblock_allow_resize();
>> +
>> +	/* Add a valid memory region used by double_array(). */
>> +	dummy_physical_memory_init();
>> +	memblock_add((phys_addr_t)get_memory_block_base(), MEM_SIZE);
>> +
>> +	for (i = 0; i < INIT_MEMBLOCK_REGIONS; i++) {
>> +		/* Reserve some fakes memory region to fulfill the memblock. */
>> +		memblock_reserve(memory_base, MEM_SIZE);
>> +
>> +		ASSERT_EQ(memblock.reserved.cnt, i + 1);
>> +		ASSERT_EQ(memblock.reserved.total_size, (i + 1) * MEM_SIZE);
>> +
>> +		/* Keep the gap so these memory region will not be merged. */
>> +		memory_base += MEM_SIZE * 2;
>> +	}
>> +
>> +	orig_region = memblock.reserved.regions;
>> +
>> +	/* This reserve the 129 memory_region, and makes it double array. */
>> +	memblock_reserve(memory_base, MEM_SIZE);
>> +
>> +	/*
>> +	 * This is the memory region size used by the doubled reserved.regions,
>> +	 * and it has been reserved due to it has been used. The size is used to
>> +	 * calculate the total_size that the memblock.reserved have now.
>> +	 */
>> +	new_reserved_regions_size = PAGE_ALIGN((INIT_MEMBLOCK_REGIONS * 2) *
>> +					sizeof(struct memblock_region));
>> +	/*
>> +	 * The double_array() will find a free memory region as the new
>> +	 * reserved.regions, and the used memory region will be reserved, so
>> +	 * there will be one more region exist in the reserved memblock. And the
>> +	 * one more reserved region's size is new_reserved_regions_size.
>> +	 */
>> +	ASSERT_EQ(memblock.reserved.cnt, INIT_MEMBLOCK_REGIONS + 1 + 1);
> 
>                                                     +2 would be fine ^
> 

Yes. It actually is +2. first +1 is the 129th region, second +1 is the 
reserved region used by double_array().

>> +	ASSERT_EQ(memblock.reserved.total_size, (INIT_MEMBLOCK_REGIONS + 1) * MEM_SIZE +
>> +						new_reserved_regions_size);
>> +	ASSERT_EQ(memblock.reserved.max, INIT_MEMBLOCK_REGIONS * 2);
>> +
> 
> Can you please elaborate what does the below sequence check?
> 

After the double_array(), we can reserve more memory region. The below 
is aimed to check it can reserve more. So this reserve a memory region 
with small base which will be put at the first reserved.regions, and I 
checked if it will be reserved ok.

>> +	/* The base is very small, so it should be insert to the first region. */
>> +	memblock_reserve(r.base, r.size);
>> +	ASSERT_EQ(memblock.reserved.regions[0].base, r.base);
>> +	ASSERT_EQ(memblock.reserved.regions[0].size, r.size);
>> +
>> +	ASSERT_EQ(memblock.reserved.cnt, INIT_MEMBLOCK_REGIONS + 2 + 1);
>> +	ASSERT_EQ(memblock.reserved.total_size, (INIT_MEMBLOCK_REGIONS + 2) * MEM_SIZE +
>> +						new_reserved_regions_size);
>> +	ASSERT_EQ(memblock.reserved.max, INIT_MEMBLOCK_REGIONS * 2);
>> +
>> +	dummy_physical_memory_cleanup();
>> +
>> +	/*
>> +	 * The current reserved.regions is occupying a range of memory that
>> +	 * allocated from dummy_physical_memory_init(). After free the memory,
>> +	 * we must not use it. So restore the origin memory region to make sure
>> +	 * the tests can run as normal and not affected by the double array.
>> +	 */
>> +	memblock.reserved.regions = orig_region;
>> +	memblock.reserved.cnt = INIT_MEMBLOCK_REGIONS;
>> +
>> +	test_pass_pop();
>> +
>> +	return 0;
>> +}
>> +
>>   static int memblock_reserve_checks(void)
>>   {
>>   	prefix_reset();
>> @@ -698,6 +784,7 @@ static int memblock_reserve_checks(void)
>>   	memblock_reserve_overlap_bottom_check();
>>   	memblock_reserve_within_check();
>>   	memblock_reserve_twice_check();
>> +	memblock_reserve_many_check();
>>   
>>   	prefix_pop();
>>   
>> -- 
>> 2.34.1
>>
>