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Date:   Sun, 18 Sep 2022 17:48:47 +0800
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Subject: Re: [PATCH v3 1/3] memblock test: Add test to memblock_add() 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: <20220913064138.407601-1-shaoqin.huang@intel.com>
 <20220913064138.407601-2-shaoqin.huang@intel.com>
 <YybkBdrHgo07uxj7@kernel.org>
From:   "Huang, Shaoqin" <shaoqin.huang@intel.com>
In-Reply-To: <YybkBdrHgo07uxj7@kernel.org>
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On 9/18/2022 5:25 PM, Mike Rapoport wrote:
> On Tue, Sep 13, 2022 at 02:41:30PM +0800, shaoqin.huang@intel.com wrote:
>> From: Shaoqin Huang <shaoqin.huang@intel.com>
>>
>> Add 129th region into 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 large enough memory
>> region, and split it into a large enough memory which can be choosed by
>> memblock_double_array(), and the left memory will be split into small
>> memory region, and add them into the memblock. It make sure the
>> memblock_double_array() will always choose the valid memory region that
>> is allocated by the dummy_physical_memory_init().
>> So memblock_double_array() must success.
>>
>> Another thing should be done is to restore the memory.regions after
>> memblock_double_array(), due to now the memory.regions is pointing to a
>> memory region allocated by dummy_physical_memory_init(). And it will
>> affect the subsequent tests if we don't restore the memory region. So
>> simply record the origin region, and restore it after the test.
>>
>> Signed-off-by: Shaoqin Huang <shaoqin.huang@intel.com>
>> ---
>>   tools/testing/memblock/tests/basic_api.c | 96 ++++++++++++++++++++++++
>>   tools/testing/memblock/tests/common.c    |  7 +-
>>   tools/testing/memblock/tests/common.h    |  3 +
>>   3 files changed, 104 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/memblock/tests/basic_api.c b/tools/testing/memblock/tests/basic_api.c
>> index a13a57ba0815..7120fd8e47b1 100644
>> --- a/tools/testing/memblock/tests/basic_api.c
>> +++ b/tools/testing/memblock/tests/basic_api.c
>> @@ -423,6 +423,101 @@ static int memblock_add_near_max_check(void)
>>   	return 0;
>>   }
>>   
>> +/*
>> + * A test that trying to add the 129th memory block.
>> + * Expect to trigger memblock_double_array() to double the
>> + * memblock.memory.max, find a new valid memory as
>> + * memory.regions.
>> + */
>> +static int memblock_add_many_check(void)
>> +{
>> +	int i;
>> +	void *orig_region;
>> +	struct region r = {
>> +		.base = SZ_16K,
>> +		.size = MEM_SIZE,
>> +	};
>> +	phys_addr_t new_memory_regions_size;
>> +	phys_addr_t base, size, block_size;
>> +
>> +	PREFIX_PUSH();
>> +
>> +	reset_memblock_regions();
>> +	memblock_allow_resize();
>> +
>> +	dummy_physical_memory_init();
>> +	/*
>> +	 * We allocated enough memory by using dummy_physical_memory_init(), and
>> +	 * split it into small block. First we split a large enough memory block
>> +	 * as the memory region which will be choosed by memblock_double_array().
>> +	 */
>> +	base = PAGE_ALIGN(dummy_physical_memory_base());
>> +	new_memory_regions_size = PAGE_ALIGN(INIT_MEMBLOCK_REGIONS * 2 *
>> +					     sizeof(struct memblock_region));
>> +	memblock_add(base, new_memory_regions_size);
> 
> Why don't you simply increase MEM_SIZE, to say 1M?
> This will make all the calculations here way simpler.
> 

Ok. I will increase MEM_SIZE. That can clean the calculation.

>> +
>> +	/*
>> +	 * For the left memory, we split them into small block and add them into
>> +	 * memblock later.
>> +	 */
>> +	base += new_memory_regions_size;
>> +	size = MEM_SIZE - new_memory_regions_size;
>> +	block_size = size / (INIT_MEMBLOCK_REGIONS * 2);
>> +
>> +	orig_region = memblock.memory.regions;
>> +
>> +	for (i = 0; i < INIT_MEMBLOCK_REGIONS; i++) {
>> +		/*
>> +		 * Add these small block to fulfill the memblock. We keep an
>> +		 * interval between the nearby memory to avoid being merged.
>> +		 */
>> +		memblock_add(base + block_size * (2 * i + 1), block_size);
>> +
>> +		ASSERT_EQ(memblock.memory.cnt, i + 2);
>> +		ASSERT_EQ(memblock.memory.total_size, new_memory_regions_size +
>> +						      (i + 1) * block_size);
>> +	}
>> +
>> +	/*
>> +	 * At there, memblock_double_array() has been succeed, check if it
>> +	 * update the memory.max.
>> +	 */
>> +	ASSERT_EQ(memblock.memory.max, INIT_MEMBLOCK_REGIONS * 2);
>> +
>> +	/* memblock_double_array() will reserve the memory it used. Check it. */
>> +	ASSERT_EQ(memblock.reserved.cnt, 1);
>> +	ASSERT_EQ(memblock.reserved.total_size, new_memory_regions_size);
>> +
>> +	/*
>> +	 * Now memblock_double_array() works fine. Let's check after the
>> +	 * double_array(), the memblock_add() still works as normal.
>> +	 */
>> +	memblock_add(r.base, r.size);
>> +	ASSERT_EQ(memblock.memory.regions[0].base, r.base);
>> +	ASSERT_EQ(memblock.memory.regions[0].size, r.size);
>> +
>> +	ASSERT_EQ(memblock.memory.cnt, INIT_MEMBLOCK_REGIONS + 2);
>> +	ASSERT_EQ(memblock.memory.total_size, INIT_MEMBLOCK_REGIONS * block_size +
>> +					      new_memory_regions_size +
>> +					      MEM_SIZE);
>> +	ASSERT_EQ(memblock.memory.max, INIT_MEMBLOCK_REGIONS * 2);
>> +
>> +	dummy_physical_memory_cleanup();
>> +
>> +	/*
>> +	 * The current memory.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.memory.regions = orig_region;
>> +	memblock.memory.cnt = INIT_MEMBLOCK_REGIONS;
>> +
>> +	test_pass_pop();
>> +
>> +	return 0;
>> +}
>> +
>>   static int memblock_add_checks(void)
>>   {
>>   	prefix_reset();
>> @@ -438,6 +533,7 @@ static int memblock_add_checks(void)
>>   	memblock_add_twice_check();
>>   	memblock_add_between_check();
>>   	memblock_add_near_max_check();
>> +	memblock_add_many_check();
>>   
>>   	prefix_pop();
>>   
>> diff --git a/tools/testing/memblock/tests/common.c b/tools/testing/memblock/tests/common.c
>> index eec6901081af..2de6a2b6efd2 100644
>> --- a/tools/testing/memblock/tests/common.c
>> +++ b/tools/testing/memblock/tests/common.c
>> @@ -5,8 +5,6 @@
>>   #include <linux/memory_hotplug.h>
>>   #include <linux/build_bug.h>
>>   
>> -#define INIT_MEMBLOCK_REGIONS			128
>> -#define INIT_MEMBLOCK_RESERVED_REGIONS		INIT_MEMBLOCK_REGIONS
>>   #define PREFIXES_MAX				15
>>   #define DELIM					": "
>>   
>> @@ -84,6 +82,11 @@ void dummy_physical_memory_cleanup(void)
>>   	free(memory_block.base);
>>   }
>>   
>> +phys_addr_t dummy_physical_memory_base(void)
>> +{
>> +	return (phys_addr_t)memory_block.base;
>> +}
>> +
>>   static void usage(const char *prog)
>>   {
>>   	BUILD_BUG_ON(ARRAY_SIZE(help_opts) != ARRAY_SIZE(long_opts) - 1);
>> diff --git a/tools/testing/memblock/tests/common.h b/tools/testing/memblock/tests/common.h
>> index 78128e109a95..ba14dc989ae9 100644
>> --- a/tools/testing/memblock/tests/common.h
>> +++ b/tools/testing/memblock/tests/common.h
>> @@ -11,6 +11,8 @@
>>   #include <../selftests/kselftest.h>
>>   
>>   #define MEM_SIZE SZ_16K
>> +#define INIT_MEMBLOCK_REGIONS			128
>> +#define INIT_MEMBLOCK_RESERVED_REGIONS		INIT_MEMBLOCK_REGIONS
>>   
>>   enum test_flags {
>>   	/* No special request. */
>> @@ -104,6 +106,7 @@ void reset_memblock_attributes(void);
>>   void setup_memblock(void);
>>   void dummy_physical_memory_init(void);
>>   void dummy_physical_memory_cleanup(void);
>> +phys_addr_t dummy_physical_memory_base(void);
>>   void parse_args(int argc, char **argv);
>>   
>>   void test_fail(void);
>> -- 
>> 2.34.1
>>
>>
>