linux-kernel - Re: [PATCH v9 3/7] mm,page_owner: Maintain own list of stack

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Date: Thu, 15 Feb 2024 11:55:20 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Oscar Salvador <osalvador@...e.de>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 Michal Hocko <mhocko@...e.com>, Marco Elver <elver@...gle.com>,
 Andrey Konovalov <andreyknvl@...il.com>,
 Alexander Potapenko <glider@...gle.com>
Subject: Re: [PATCH v9 3/7] mm,page_owner: Maintain own list of stack_records
 structs

On 2/14/24 18:01, Oscar Salvador wrote:
> page_owner needs to increment a stack_record refcount when a new allocation
> occurs, and decrement it on a free operation.
> In order to do that, we need to have a way to get a stack_record from a
> handle.
> Implement __stack_depot_get_stack_record() which just does that, and make
> it public so page_owner can use it.
> 
> Also, traversing all stackdepot buckets comes with its own complexity,
> plus we would have to implement a way to mark only those stack_records
> that were originated from page_owner, as those are the ones we are
> interested in.
> For that reason, page_owner maintains its own list of stack_records,
> because traversing that list is faster than traversing all buckets
> while keeping at the same time a low complexity.
> 
> For now, add to stack_list only the stack_records of dummy_handle and
> failure_handle, and set their refcount of 1.
> 
> Further patches will add code to increment or decrement stack_records
> count on allocation and free operation.
> 
> Signed-off-by: Oscar Salvador <osalvador@...e.de>

Reviewed-by: Vlastimil Babka <vbabka@...e.cz>