On Wed, Jul 17, 2024 at 04:05:35AM +0100, Matthew Wilcox wrote:
>On Wed, Jul 17, 2024 at 03:03:13AM +0000, Wei Yang wrote:
>> On Wed, Jul 17, 2024 at 03:45:40AM +0100, Matthew Wilcox wrote:
>> >On Wed, Jul 17, 2024 at 02:41:26AM +0000, Wei Yang wrote:
>> >> On Wed, Jul 17, 2024 at 03:06:01AM +0100, Matthew Wilcox wrote:
>> >> >On Wed, Jul 17, 2024 at 01:41:42AM +0000, Wei Yang wrote:
>> >> >> The comment here describe the size of struct maple_arange_64.
>> >> >>
>> >> >> The value here is not correct. Fix it with the correct value.
>> >> >
>> >> >You are wrong.
>> >>
>> >> You mean the my value is wrong or my understanding is wrong?
>> >
>> >Yes.
>>
>> I don't get it.
>>
>> Would you mind sharing some light on what 240 bytes stands for? I don't figure
>> out what size it represents.
>
>You first. How did you determine the new value you used?
Sure.
My understanding of the comment is to represent the size of related data
structures, eg. maple_node, maple_range_64 and maple_arange_64.
I add following code in test to the size of those structures.
diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index cea050675da2..93e77dea7f0b 100644
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -3645,6 +3645,10 @@ static int __init maple_tree_seed(void)
5003, 5002};
void *ptr = &set;
+ pr_info("\nsizeof struct maple_node %ld\n", sizeof(struct maple_node));
+ pr_info("\nsizeof struct maple_range_64 %ld\n", sizeof(struct maple_range_64));
+ pr_info("\nsizeof struct maple_arange_64 %ld\n", sizeof(struct maple_arange_64));
Then insert the test module.
$ sudo insmod lib/test_maple_tree.ko
[ 152.152382]
[ 152.152382] sizeof struct maple_node 256
[ 152.153043]
[ 152.153043] sizeof struct maple_range_64 256
[ 152.153561]
[ 152.153561] sizeof struct maple_arange_64 248
The first two is the same as in comment, while the third one is not the same.
The 248 for 64BIT comes from here.
For 32BIT, I copied structure definition to a user space source and compile
with -m32. The size of structure maple_arange_64 is 256. This is where 256
comes from.
--
Wei Yang
Help you, Help me
