Re: [PATCH v3 4/4] mm/page_owner: Record task command name

[Waiman Long <longman@redhat.com>]

On 1/31/22 15:54, Roman Gushchin wrote:
> On Mon, Jan 31, 2022 at 02:23:08PM -0500, Waiman Long wrote:
>> The page_owner information currently includes the pid of the calling
>> task. That is useful as long as the task is still running. Otherwise,
>> the number is meaningless. To have more information about the allocating
>> tasks that had exited by the time the page_owner information is
>> retrieved, we need to store the command name of the task.
>>
>> Add a new comm field into page_owner structure to store the command name
>> and display it when the page_owner information is retrieved. Only the
>> first 15 characters of the command name will be copied, but that should
>> be enough in most cases. Even for those commands with longer names,
>> it shouldn't be hard to guess what they are.
>>
>> Signed-off-by: Waiman Long <longman@redhat.com>
>> ---
>>   mm/page_owner.c | 16 ++++++++++++----
>>   1 file changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/page_owner.c b/mm/page_owner.c
>> index a471c74c7fe0..8b2b381fd986 100644
>> --- a/mm/page_owner.c
>> +++ b/mm/page_owner.c
>> @@ -20,6 +20,7 @@
>>    * to use off stack temporal storage
>>    */
>>   #define PAGE_OWNER_STACK_DEPTH (16)
>> +#define PAGE_OWNER_COMM_LEN	16
> Not sure I understand why not simply use TASK_COMM_LEN ?

Yes, you are right. I thought TASK_COMM_LEN is larger than 16 without 
actually checking it. Will fix that.

Cheers,
Longman