[dpdk-dev] [PATCH v3] eal: fix create user mem map repeatedly when it exists

[Burakov, Anatoly]

On 20-Oct-20 3:09 PM, Thomas Monjalon wrote:
> 16/10/2020 11:28, wangyunjian:
>> From: Yunjian Wang <wangyunjian at huawei.com>
>>
>> Currently, a issue that a container has many devices and the
>> application will map the same memory many times. The kernel
>> driver returns EEXIST as long as there are overlapping memory
>> areas. As a result, we repeatedly create new user mem map entry
>> for the same memory segment and this will lead to no more space
>> for other user mem maps.
>>
>> To resolve the issue, add support to remove the same entry in
>> the function compact_user_maps().
> 
> Sorry I don't understand the explanations above.
> Anatoly, please could you help in rewording?
> 
> 
> 

Apologies for delay, fell through the cracks.

Suggested rewording:

Currently, user mem maps will check if the newly mapped area is adjacent 
to any existing mapping, but will not check if the mapping is identical 
because it assumes that the API will never get called with the same 
mapping twice. This will result in duplicate entries in the user mem 
maps list.

Fix it by also checking for duplicate mappings, and skipping them if 
they are found.

-- 
Thanks,
Anatoly