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Date: Thu, 1 Sep 2022 16:43:40 +0800
From: "Huang, Shaoqin" <shaoqin.huang@...el.com>
To: Mike Rapoport <rppt@...nel.org>
CC: Karolina Drobnik <karolinadrobnik@...il.com>,
Rebecca Mckeever <remckee0@...il.com>,
David Hildenbrand <david@...hat.com>, <linux-mm@...ck.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] memblock test: Add test to memblock_reserve() 129th
region
On 9/1/2022 4:08 PM, Mike Rapoport wrote:
> On Tue, Aug 30, 2022 at 09:49:18AM +0800, shaoqin.huang@...el.com wrote:
>> From: Shaoqin Huang <shaoqin.huang@...el.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@...el.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
>>
>
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