On Sun, Apr 28, 2024 at 09:40:33AM +0300, Mike Rapoport wrote:
>On Thu, Apr 25, 2024 at 07:19:23AM +0000, Wei Yang wrote:
>> This may trigger the case fixed by commit 48c3b583bbdd ("mm/memblock:
>> fix overlapping allocation when doubling reserved array").
>>
>> This is done by adding the 129th reserve region into memblock.memory. If
>> memblock_double_array() use this reserve region as new array, it fails.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
>> ---
>> tools/testing/memblock/tests/basic_api.c | 123 +++++++++++++++++++++++
>> tools/testing/memblock/tests/common.c | 4 +-
>> tools/testing/memblock/tests/common.h | 1 +
>> 3 files changed, 126 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/memblock/tests/basic_api.c b/tools/testing/memblock/tests/basic_api.c
>> index 1ae62272867a..748950e02589 100644
>> --- a/tools/testing/memblock/tests/basic_api.c
>> +++ b/tools/testing/memblock/tests/basic_api.c
>> @@ -991,6 +991,128 @@ static int memblock_reserve_many_check(void)
>> return 0;
>> }
>>
>> +/* Keep the gap so these memory region will not be merged. */
>
>The gap where? What regions should not be merged?
>Also please add a comment with the test description
>
>> +#define MEMORY_BASE_OFFSET(idx, offset) ((offset) + (MEM_SIZE * 2) * (idx))
>> +static int memblock_reserve_many_may_conflict_check(void)
>> +{
>> + int i, skip;
>> + void *orig_region;
>> + struct region r = {
>> + .base = SZ_16K,
>> + .size = SZ_16K,
>> + };
>> + phys_addr_t new_reserved_regions_size;
>> +
>> + /*
>> + * 0 1 129
>> + * +---+ +---+ +---+
>> + * |32K| |32K| .. |32K|
>> + * +---+ +---+ +---+
>> + *
>> + * Pre-allocate the range for 129 memory block + one range for double
>> + * memblock.reserved.regions at idx 0.
>> + * See commit 48c3b583bbdd ("mm/memblock: fix overlapping allocation
>> + * when doubling reserved array")
>
>Sorry, but I'm failing to parse it
>
Sorry for missed this one. You mean how this case is triggered?
Suppose current memblock looks like this:
0 1
memblock.memory +---+ +---+
|32K| |32K|
+---+ +---+
0 2 128
memblock.reserved+---+ +---+ +---+
|32K| |32K| .. |32K|
+---+ +---+ +---+
^
|
Now we want to reserve range 1 here. Since there are 128 blocks in
memblock.reserved, it will double array. Now memblock_double_array() will
"find" available range in memblock.memory.
Since we set top down, it will find memblock.memory.regions[1]. This conflict
the range we want to reserve.
--
Wei Yang
Help you, Help me
