On Mon, Jan 05, 2026 at 08:04:22AM -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 <[email protected]>
> ---
> include/trace/events/vmscan.h | 79 ++++++++++++++++++++---------------
> mm/shrinker.c | 2 +-
> mm/vmscan.c | 17 ++++----
> 3 files changed, 56 insertions(+), 42 deletions(-)
>
> diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> index 490958fa10dee..93a9a9ba9405d 100644
> --- a/include/trace/events/vmscan.h
> +++ b/include/trace/events/vmscan.h
> @@ -208,31 +215,34 @@ TRACE_EVENT(mm_shrink_slab_start,
> TP_fast_assign(
> __entry->shr = shr;
> __entry->shrink = shr->scan_objects;
> - __entry->nid = sc->nid;
> __entry->nr_objects_to_shrink = nr_objects_to_shrink;
> __entry->gfp_flags = (__force unsigned long)sc->gfp_mask;
> __entry->cache_items = cache_items;
> __entry->delta = delta;
> __entry->total_scan = total_scan;
> __entry->priority = priority;
> + __entry->nid = sc->nid;
> + __entry->memcg_id = sc->memcg ?
> cgroup_id(sc->memcg->css.cgroup) : 0;
Hi Thomas, this is breaking CONFIG_MEMCG=n builds.
In file included from ./include/trace/define_trace.h:132,
from ./include/trace/events/vmscan.h:569,
from mm/vmscan.c:73:
./include/trace/events/vmscan.h: In function
‘do_trace_event_raw_event_mm_shrink_slab_start’:
./include/trace/events/vmscan.h:248:68: error: invalid use of undefined type
‘struct mem_cgroup’
248 | __entry->memcg_id = sc->memcg ?
cgroup_id(sc->memcg->css.cgroup) : 0;
| ^~
./include/trace/trace_events.h:427:11: note: in definition of macro
‘__DECLARE_EVENT_CLASS’
427 | { assign; }
\
| ^~~~~~
./include/trace/trace_events.h:435:23: note: in expansion of macro ‘PARAMS’
435 | PARAMS(assign), PARAMS(print))
\
| ^~~~~~
./include/trace/trace_events.h:40:9: note: in expansion of macro
‘DECLARE_EVENT_CLASS’
40 | DECLARE_EVENT_CLASS(name, \
| ^~~~~~~~~~~~~~~~~~~
./include/trace/trace_events.h:44:30: note: in expansion of macro ‘PARAMS’
44 | PARAMS(assign), \
| ^~~~~~
./include/trace/events/vmscan.h:214:1: note: in expansion of macro ‘TRACE_EVENT’
214 | TRACE_EVENT(mm_shrink_slab_start,
| ^~~~~~~~~~~
./include/trace/events/vmscan.h:237:9: note: in expansion of macro
‘TP_fast_assign’
237 | TP_fast_assign(
| ^~~~~~~~~~~~~~
./include/trace/events/vmscan.h: In function
‘do_trace_event_raw_event_mm_shrink_slab_end’:
./include/trace/events/vmscan.h:293:56: error: invalid use of undefined type
‘struct mem_cgroup’
293 | __entry->memcg_id = cgroup_id(sc->memcg->css.cgroup);
| ^~
./include/trace/trace_events.h:427:11: note: in definition of macro
‘__DECLARE_EVENT_CLASS’
427 | { assign; }
\
| ^~~~~~
./include/trace/trace_events.h:435:23: note: in expansion of macro ‘PARAMS’
435 | PARAMS(assign), PARAMS(print))
\
| ^~~~~~
./include/trace/trace_events.h:40:9: note: in expansion of macro
‘DECLARE_EVENT_CLASS’
40 | DECLARE_EVENT_CLASS(name, \
| ^~~~~~~~~~~~~~~~~~~
./include/trace/trace_events.h:44:30: note: in expansion of macro ‘PARAMS’
44 | PARAMS(assign), \
| ^~~~~~
./include/trace/events/vmscan.h:266:1: note: in expansion of macro ‘TRACE_EVENT’
266 | TRACE_EVENT(mm_shrink_slab_end,
| ^~~~~~~~~~~
./include/trace/events/vmscan.h:285:9: note: in expansion of macro
‘TP_fast_assign’
285 | TP_fast_assign(
| ^~~~~~~~~~~~~~
In file included from ./include/trace/define_trace.h:133:
./include/trace/events/vmscan.h: In function
‘do_perf_trace_mm_shrink_slab_start’:
./include/trace/events/vmscan.h:248:68: error: invalid use of undefined type
‘struct mem_cgroup’
248 | __entry->memcg_id = sc->memcg ?
cgroup_id(sc->memcg->css.cgroup) : 0;
| ^~
./include/trace/perf.h:51:11: note: in definition of macro
‘__DECLARE_EVENT_CLASS’
51 | { assign; }
\
| ^~~~~~
./include/trace/perf.h:67:23: note: in expansion of macro ‘PARAMS’
67 | PARAMS(assign), PARAMS(print))
\
| ^~~~~~
./include/trace/trace_events.h:40:9: note: in expansion of macro
‘DECLARE_EVENT_CLASS’
40 | DECLARE_EVENT_CLASS(name, \
| ^~~~~~~~~~~~~~~~~~~
./include/trace/trace_events.h:44:30: note: in expansion of macro ‘PARAMS’
44 | PARAMS(assign), \
| ^~~~~~
./include/trace/events/vmscan.h:214:1: note: in expansion of macro ‘TRACE_EVENT’
214 | TRACE_EVENT(mm_shrink_slab_start,
| ^~~~~~~~~~~
./include/trace/events/vmscan.h:237:9: note: in expansion of macro
‘TP_fast_assign’
237 | TP_fast_assign(
| ^~~~~~~~~~~~~~
./include/trace/events/vmscan.h: In function ‘do_perf_trace_mm_shrink_slab_end’:
./include/trace/events/vmscan.h:293:56: error: invalid use of undefined type
‘struct mem_cgroup’
293 | __entry->memcg_id = cgroup_id(sc->memcg->css.cgroup);
| ^~
./include/trace/perf.h:51:11: note: in definition of macro
‘__DECLARE_EVENT_CLASS’
51 | { assign; }
\
| ^~~~~~
./include/trace/perf.h:67:23: note: in expansion of macro ‘PARAMS’
67 | PARAMS(assign), PARAMS(print))
\
| ^~~~~~
./include/trace/trace_events.h:40:9: note: in expansion of macro
‘DECLARE_EVENT_CLASS’
40 | DECLARE_EVENT_CLASS(name, \
| ^~~~~~~~~~~~~~~~~~~
./include/trace/trace_events.h:44:30: note: in expansion of macro ‘PARAMS’
44 | PARAMS(assign), \
| ^~~~~~
./include/trace/events/vmscan.h:266:1: note: in expansion of macro ‘TRACE_EVENT’
266 | TRACE_EVENT(mm_shrink_slab_end,
| ^~~~~~~~~~~
./include/trace/events/vmscan.h:285:9: note: in expansion of macro
‘TP_fast_assign’
285 | TP_fast_assign(
| ^~~~~~~~~~~~~~
CC arch/x86/mm/extable.o
make[3]: *** [scripts/Makefile.build:287: mm/vmscan.o] Error 1
make[2]: *** [scripts/Makefile.build:556: mm] Error 2
make[2]: *** Waiting for unfinished jobs....
--
Cheers,
Harry / Hyeonggon
> ),
>
> - TP_printk("%pS %p: nid: %d objects to shrink %ld gfp_flags %s cache
> items %ld delta %lld total_scan %ld priority %d",
> + TP_printk("%pS %p: nid: %d memcg_id: %u objects to shrink %ld gfp_flags
> %s cache items %ld delta %lld total_scan %ld priority %d",
> __entry->shrink,
> __entry->shr,
> __entry->nid,
> + __entry->memcg_id,
> __entry->nr_objects_to_shrink,
> show_gfp_flags(__entry->gfp_flags),
> __entry->cache_items,
> @@ -242,36 +252,39 @@ TRACE_EVENT(mm_shrink_slab_start,
> );
>
> TRACE_EVENT(mm_shrink_slab_end,
> - TP_PROTO(struct shrinker *shr, int nid, int shrinker_retval,
> + TP_PROTO(struct shrinker *shr, struct shrink_control *sc, int
> shrinker_retval,
> long unused_scan_cnt, long new_scan_cnt, long total_scan),
>
> - TP_ARGS(shr, nid, shrinker_retval, unused_scan_cnt, new_scan_cnt,
> + TP_ARGS(shr, sc, shrinker_retval, unused_scan_cnt, new_scan_cnt,
> total_scan),
>
> TP_STRUCT__entry(
> __field(struct shrinker *, shr)
> - __field(int, nid)
> __field(void *, shrink)
> __field(long, unused_scan)
> __field(long, new_scan)
> - __field(int, retval)
> __field(long, total_scan)
> + __field(int, nid)
> + __field(int, retval)
> + __field(unsigned short, memcg_id)
> ),
>
> TP_fast_assign(
> __entry->shr = shr;
> - __entry->nid = nid;
> __entry->shrink = shr->scan_objects;
> __entry->unused_scan = unused_scan_cnt;
> __entry->new_scan = new_scan_cnt;
> - __entry->retval = shrinker_retval;
> __entry->total_scan = total_scan;
> + __entry->nid = sc->nid;
> + __entry->retval = shrinker_retval;
> + __entry->memcg_id = cgroup_id(sc->memcg->css.cgroup);
> ),
>
> - TP_printk("%pS %p: nid: %d unused scan count %ld new scan count %ld
> total_scan %ld last shrinker return val %d",
> + TP_printk("%pS %p: nid: %d memcg_id: %u unused scan count %ld new scan
> count %ld total_scan %ld last shrinker return val %d",
> __entry->shrink,
> __entry->shr,
> __entry->nid,
> + __entry->memcg_id,
> __entry->unused_scan,
> __entry->new_scan,
> __entry->total_scan,
> @@ -504,9 +517,9 @@ TRACE_EVENT(mm_vmscan_node_reclaim_begin,
>
> DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template,
> mm_vmscan_node_reclaim_end,
>
> - TP_PROTO(unsigned long nr_reclaimed),
> + TP_PROTO(unsigned long nr_reclaimed, unsigned short memcg_id),
>
> - TP_ARGS(nr_reclaimed)
> + TP_ARGS(nr_reclaimed, memcg_id)
> );
>
> TRACE_EVENT(mm_vmscan_throttled,
