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Date:   Tue, 6 Sep 2022 22:49:29 +0800
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Subject: Re: [PATCH v2 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: <20220902024007.58041-1-shaoqin.huang@intel.com>
 <20220902024007.58041-2-shaoqin.huang@intel.com>
 <YxdDqZgSjBKjcvYE@kernel.org>
From:   "Huang, Shaoqin" <shaoqin.huang@intel.com>
In-Reply-To: <YxdDqZgSjBKjcvYE@kernel.org>
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On 9/6/2022 8:57 PM, Mike Rapoport wrote:
> On Fri, Sep 02, 2022 at 10:39:59AM +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 some valid memory region,
>> and add it 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 | 91 ++++++++++++++++++++++++
>>   tools/testing/memblock/tests/common.c    | 15 +++-
>>   tools/testing/memblock/tests/common.h    |  4 ++
>>   3 files changed, 108 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/memblock/tests/basic_api.c b/tools/testing/memblock/tests/basic_api.c
>> index a13a57ba0815..b9877344d3a1 100644
>> --- a/tools/testing/memblock/tests/basic_api.c
>> +++ b/tools/testing/memblock/tests/basic_api.c
>> @@ -423,6 +423,96 @@ 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,
>> +	};
>> +	/* Record these allocated memory, they will be free at the end. */
>> +	phys_addr_t base[INIT_MEMBLOCK_REGIONS + 1];
>> +
>> +	PREFIX_PUSH();
>> +
>> +	reset_memblock_regions();
>> +	memblock_allow_resize();
>> +
>> +	for (i = 0; i < INIT_MEMBLOCK_REGIONS; i++) {
>> +		/* Add some memory region to fulfill the memblock. */
>> +		dummy_physical_memory_init();
>> +		base[i] = dummy_physical_memory_base();
>> +		memblock_add(base[i], MEM_SIZE);
> 
> Looks like we are going in rounds.
> The simulated physical memory is what dummy_physical_memory_init()
> allocates. Every memblock_add() may take a range from that "physical
> memory" and register it with memblock. There is no need to allocate new
> chunk for every memblock_add(), just make sure that
> dummy_physical_memory_init() allocates enough memory.
> 

Do you mean dummy_physical_memory_init() a large memory? And split it 
into 128 regions to fulfill the memory.regions. If so, we may need to 
modify the MEM_SIZE (now is 16K) to a larger size to make double_array() 
succeed due to the new memory.regions will occupy 8K memory.

>> +
>> +		ASSERT_EQ(memblock.memory.cnt, i + 1);
>> +		ASSERT_EQ(memblock.memory.total_size, (i + 1) * MEM_SIZE);
>> +	}
>> +
>> +	orig_region = memblock.memory.regions;
>> +
>> +	/*
>> +	 * This adds the 129 memory_region, and makes it double array. Now
>> +	 * MEM_SIZE is 16K, which is enough, the doubled array will occupy 8K
>> +	 * memory region, so it must success.
>> +	 */
>> +	dummy_physical_memory_init();
>> +	base[i] = dummy_physical_memory_base();
>> +	memblock_add(base[i], MEM_SIZE);
>> +
>> +	ASSERT_EQ(memblock.memory.cnt, INIT_MEMBLOCK_REGIONS + 1);
>> +	ASSERT_EQ(memblock.memory.total_size, (INIT_MEMBLOCK_REGIONS + 1) * MEM_SIZE);
>> +	ASSERT_EQ(memblock.memory.max, INIT_MEMBLOCK_REGIONS * 2);
>> +
>> +	ASSERT_EQ(memblock.reserved.cnt, 1);
>> +	/* This is the size used by new memory.regions. Check it. */
>> +	ASSERT_EQ(memblock.reserved.total_size, PAGE_ALIGN(INIT_MEMBLOCK_REGIONS * 2 *
>> +						sizeof(struct memblock_region)));
>> +
>> +	/*
>> +	 * After double array, we want to make sure the memblock.memory.regions
>> +	 * is actually on a valid memory, so we try to add a memory region which
> 
> What do you mean by "actually on a valid memory"? How would
> memblock_double_array() succeed otherwise?
> 

The code before this line has checked the memblock_double_array() 
succeed. I just want to test after it succeed, add a new memory region 
into it will still succeed. So the "actually on a valid memory" is a 
little confused, I want to modify "After double array, we want to make 
sure the memblock.memory.regions is actually on a valid memory" to "The 
next we want to test if the memblock_add() still succeed after 
memblock_double_array()".

>> +	 * the base is very small, it should be insert to the first region. And
>> +	 * the memory.cnt and memory.total_size will both be changed.
>> +	 * Let's check it.
>> +	 */
>> +	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 + 2) * MEM_SIZE);
>> +	ASSERT_EQ(memblock.memory.max, INIT_MEMBLOCK_REGIONS * 2);
>> +
>> +	/*
>> +	 * Due to we dummy_physical_memory_init() many memory region in this
>> +	 * test, we need to free it. Instead of expose the memory_block and
>> +	 * directly modify it's base, we pass an array which record all the
>> +	 * memory base that we allocated to this function, and let it to do the
>> +	 * clean job.
>> +	 */
>> +	dummy_physical_memory_cleanup_many(base, INIT_MEMBLOCK_REGIONS + 1);
>> +
>> +	/*
>> +	 * 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 +528,7 @@ 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..1fb347c5c099 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 +82,19 @@ void dummy_physical_memory_cleanup(void)
>>   	free(memory_block.base);
>>   }
>>   
>> +void dummy_physical_memory_cleanup_many(phys_addr_t *base, int cnt)
>> +{
>> +	for (int i = 0; i < cnt; i++) {
>> +		memory_block.base = (void *)base[i];
>> +		dummy_physical_memory_cleanup();
>> +	}
>> +}
>> +
>> +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..310f0be2b2a2 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 +106,8 @@ void reset_memblock_attributes(void);
>>   void setup_memblock(void);
>>   void dummy_physical_memory_init(void);
>>   void dummy_physical_memory_cleanup(void);
>> +void dummy_physical_memory_cleanup_many(phys_addr_t *base, int cnt);
>> +phys_addr_t dummy_physical_memory_base(void);
>>   void parse_args(int argc, char **argv);
>>   
>>   void test_fail(void);
>> -- 
>> 2.34.1
>>
>