Commit 9d3edf96 authored by Shakeel Butt's avatar Shakeel Butt Committed by Andrew Morton
Browse files

memcg: add nmi-safe update for MEMCG_KMEM 

The objcg based kmem charging and uncharging code path needs to update
MEMCG_KMEM appropriately.  Let's add support to update MEMCG_KMEM in
nmi-safe way for those code paths.

Link: https://lkml.kernel.org/r/20250519063142.111219-4-shakeel.butt@linux.dev


Signed-off-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 940b01fc

mm/memcontrol.c

+19 −2
Original line number Diff line number Diff line
@@ -2715,6 +2715,23 @@ struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio) 
	return objcg;

}



#ifdef CONFIG_MEMCG_NMI_SAFETY_REQUIRES_ATOMIC

static inline void account_kmem_nmi_safe(struct mem_cgroup *memcg, int val)

{

	if (likely(!in_nmi())) {

		mod_memcg_state(memcg, MEMCG_KMEM, val);

	} else {

		/* TODO: add to cgroup update tree once it is nmi-safe. */

		atomic_add(val, &memcg->kmem_stat);

	}

}

#else

static inline void account_kmem_nmi_safe(struct mem_cgroup *memcg, int val)

{

	mod_memcg_state(memcg, MEMCG_KMEM, val);

}

#endif



/*

 * obj_cgroup_uncharge_pages: uncharge a number of kernel pages from a objcg

 * @objcg: object cgroup to uncharge
@@ -2727,7 +2744,7 @@ static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg, 


	memcg = get_mem_cgroup_from_objcg(objcg);



	mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages);

	account_kmem_nmi_safe(memcg, -nr_pages);

	memcg1_account_kmem(memcg, -nr_pages);

	if (!mem_cgroup_is_root(memcg))

		refill_stock(memcg, nr_pages);
@@ -2755,7 +2772,7 @@ static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp, 
	if (ret)

		goto out;



	mod_memcg_state(memcg, MEMCG_KMEM, nr_pages);

	account_kmem_nmi_safe(memcg, nr_pages);

	memcg1_account_kmem(memcg, nr_pages);

out:

	css_put(&memcg->css);