Re: [PATCH v5 2/3] mm: vmscan: add cgroup IDs to vmscan tracepoints

[Shakeel Butt <shakeel.butt@linux.dev>]

On Thu, Jan 22, 2026 at 10:25:09AM -0800, Thomas Ballasi wrote:
> Memory reclaim events are currently difficult to attribute to
> specific cgroups, making debugging memory pressure issues
> challenging.  This patch adds memory cgroup ID (memcg_id) to key
> vmscan tracepoints to enable better correlation and analysis.
> 
> For operations not associated with a specific cgroup, the field
> is defaulted to 0.
> 
> Signed-off-by: Thomas Ballasi <tballasi@linux.microsoft.com>
> ---
>  include/trace/events/vmscan.h | 83 ++++++++++++++++++++---------------
>  mm/shrinker.c                 |  6 ++-
>  mm/vmscan.c                   | 17 +++----
>  3 files changed, 61 insertions(+), 45 deletions(-)
> 
> diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> index 490958fa10dee..20160e79eb0d7 100644
> --- a/include/trace/events/vmscan.h
> +++ b/include/trace/events/vmscan.h
> @@ -114,85 +114,92 @@ TRACE_EVENT(mm_vmscan_wakeup_kswapd,
>  
>  DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_begin_template,
>  
> -	TP_PROTO(int order, gfp_t gfp_flags),
> +	TP_PROTO(gfp_t gfp_flags, int order, u64 memcg_id),
>  
> -	TP_ARGS(order, gfp_flags),
> +	TP_ARGS(gfp_flags, order, memcg_id),
>  
>  	TP_STRUCT__entry(
> -		__field(	int,	order		)
>  		__field(	unsigned long,	gfp_flags	)
> +		__field(	u64,	memcg_id	)
> +		__field(	int,	order		)
>  	),
>  
>  	TP_fast_assign(
> -		__entry->order		= order;
>  		__entry->gfp_flags	= (__force unsigned long)gfp_flags;
> +		__entry->order		= order;
> +		__entry->memcg_id	= memcg_id;

Please pass memcg pointer to tracepoints and call mem_cgroup_id(memcg)
here.