Commit 91b71e78 authored by Yosry Ahmed's avatar Yosry Ahmed Committed by Andrew Morton
Browse files

mm: memcg: add NULL check to obj_cgroup_put() 

9 out of 16 callers perform a NULL check before calling obj_cgroup_put(). 
Move the NULL check in the function, similar to mem_cgroup_put().  The
unlikely() NULL check in current_objcg_update() was left alone to avoid
dropping the unlikey() annotation as this a fast path.

Link: https://lkml.kernel.org/r/20240316015803.2777252-1-yosryahmed@google.com


Signed-off-by: default avatarYosry Ahmed <yosryahmed@google.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5b0a6700

include/linux/memcontrol.h

+2 −1
Original line number Diff line number Diff line
@@ -818,6 +818,7 @@ static inline void obj_cgroup_get_many(struct obj_cgroup *objcg, 


static inline void obj_cgroup_put(struct obj_cgroup *objcg)

{

	if (objcg)

		percpu_ref_put(&objcg->refcnt);

}

kernel/bpf/memalloc.c

+2 −4
Original line number Diff line number Diff line
@@ -759,7 +759,6 @@ void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma) 
			rcu_in_progress += atomic_read(&c->call_rcu_ttrace_in_progress);

			rcu_in_progress += atomic_read(&c->call_rcu_in_progress);

		}

		if (ma->objcg)

		obj_cgroup_put(ma->objcg);

		destroy_mem_alloc(ma, rcu_in_progress);

	}
@@ -776,7 +775,6 @@ void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma) 
				rcu_in_progress += atomic_read(&c->call_rcu_in_progress);

			}

		}

		if (ma->objcg)

		obj_cgroup_put(ma->objcg);

		destroy_mem_alloc(ma, rcu_in_progress);

	}

mm/memcontrol.c

+6 −12
Original line number Diff line number Diff line
@@ -2369,7 +2369,6 @@ static void drain_local_stock(struct work_struct *dummy) 
	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);



	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);

	if (old)

	obj_cgroup_put(old);

}
@@ -3145,7 +3144,6 @@ static struct obj_cgroup *current_objcg_update(void) 
		if (old) {

			old = (struct obj_cgroup *)

				((unsigned long)old & ~CURRENT_OBJCG_UPDATE_FLAG);

			if (old)

			obj_cgroup_put(old);



			old = NULL;
@@ -3418,7 +3416,6 @@ void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, 
		mod_objcg_mlstate(objcg, pgdat, idx, nr);



	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);

	if (old)

	obj_cgroup_put(old);

}
@@ -3546,7 +3543,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, 
	}



	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);

	if (old)

	obj_cgroup_put(old);



	if (nr_pages)
@@ -5468,7 +5464,6 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) 
{

	int node;



	if (memcg->orig_objcg)

	obj_cgroup_put(memcg->orig_objcg);



	for_each_node(node)
@@ -6620,7 +6615,6 @@ static void mem_cgroup_exit(struct task_struct *task) 


	objcg = (struct obj_cgroup *)

		((unsigned long)objcg & ~CURRENT_OBJCG_UPDATE_FLAG);

	if (objcg)

	obj_cgroup_put(objcg);



	/*

mm/zswap.c

+1 −2
Original line number Diff line number Diff line
@@ -1618,7 +1618,6 @@ bool zswap_store(struct folio *folio) 
freepage:

	zswap_entry_cache_free(entry);

reject:

	if (objcg)

	obj_cgroup_put(objcg);

check_old:

	/*