Re: [PATCH v2 2/3] mm, page_owner: decouple freeing stack trace from debug_pagealloc

Vlastimil Babka
2019-10-01T14:15:21Z

On 10/1/19 3:18 PM, Qian Cai wrote:
> On Tue, 2019-10-01 at 14:35 +0200, Vlastimil Babka wrote:
>> On 10/1/19 2:32 PM, Vlastimil Babka wrote:
>>
>> Or suggest how to replace page_owner=on with something else (page_owner=full?)
>> and I can change that. But I don't want to implement a variant where we store only
>> the freeing stack, though.
>
> I don't know why you think it is a variant. It sounds to me it is a natural
> extension that belongs to page_owner=on that it could always store freeing stack
> to help with debugging. Then, it could make implementation easier without all
> those different combinations you mentioned in the patch description that could
> confuse anyone.
>
> If someone complains about the overhead introduced to the existing page_owner=on
> users, then I think we should have some number to prove that say how much
> overhead there by storing freeing stack in page_owner=on, 10%, 50%?

I'll wait a few days for these overhead objections and if there are none I will
post a version that removes the parameter and stores freeing stack unconditionally.