linux-kernel - Re: [PATCH 1/3] mm/page_owner: add option 'print_handle' for 'show

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Message-ID: <d05a76ffe2969b8542db961ef1f41a0e@igalia.com>
Date: Thu, 25 Sep 2025 19:25:59 -0300
From: Mauricio Faria de Oliveira <mfo@...lia.com>
To: Joshua Hahn <joshua.hahnjy@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Vlastimil Babka
 <vbabka@...e.cz>, Oscar Salvador <osalvador@...e.de>, Suren Baghdasaryan
 <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>, Brendan Jackman
 <jackmanb@...gle.com>, Johannes Weiner <hannes@...xchg.org>, Zi Yan
 <ziy@...dia.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 kernel-dev@...lia.com
Subject: Re: [PATCH 1/3] mm/page_owner: add option 'print_handle' for
 'show_stacks'

On 2025-09-25 17:28, Joshua Hahn wrote:
> On Wed, 24 Sep 2025 14:40:21 -0300 Mauricio Faria de Oliveira <mfo@...lia.com> wrote:
> 
>> For monitoring the memory usage per stack trace, it is more efficient to
>> use the handle number as unique identifier of a stack trace than to, for
>> example, read/hash all stack traces to uniquely identify them everytime.
>> 
>> The handle number is a unique identifier for stack traces in stackdepot.
>> 
>> This patch adds the option 'print_handle' to print the handle number of
>> stack traces in 'show_stacks'.
> 
>> @@ -887,6 +887,7 @@ static void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
>>  }
>>  
>>  static unsigned long page_owner_pages_threshold;
>> +static bool page_owner_print_handle;
> 
> Hi Mauricio,
> 
> Quick nit -- If I understand your cover letter correctly, you want
> page_owner_print_handle to be false by default, should we initialize this
> to false?

Hey Joshua,

In this case, it is not needed, as static variables don't need to be
initialized to false/0. This is handled as an error in checkpatch.pl,
so it should not be added even for completeness.

Thanks for checking this.

-- 
Mauricio