From: Alexei Starovoitov Date: Thu, 6 Jul 2023 03:34:36 +0000 (-0700) Subject: bpf: Let free_all() return the number of freed elements. X-Git-Tag: microblaze-v6.8~638^2~405^2~6^2~11 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=9de3e81521b4d943c9ec27ae2c871292c12f1409;p=linux-2.6-microblaze.git bpf: Let free_all() return the number of freed elements. Let free_all() helper return the number of freed elements. It's not used in this patch, but helps in debug/development of bpf_mem_alloc. For example this diff for __free_rcu(): - free_all(llist_del_all(&c->waiting_for_gp_ttrace), !!c->percpu_size); + printk("cpu %d freed %d objs after tasks trace\n", raw_smp_processor_id(), + free_all(llist_del_all(&c->waiting_for_gp_ttrace), !!c->percpu_size)); would show how busy RCU tasks trace is. In artificial benchmark where one cpu is allocating and different cpu is freeing the RCU tasks trace won't be able to keep up and the list of objects would keep growing from thousands to millions and eventually OOMing. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Hou Tao Link: https://lore.kernel.org/bpf/20230706033447.54696-4-alexei.starovoitov@gmail.com --- diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index b0011217be6c..693651d2648b 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -223,12 +223,16 @@ static void free_one(void *obj, bool percpu) kfree(obj); } -static void free_all(struct llist_node *llnode, bool percpu) +static int free_all(struct llist_node *llnode, bool percpu) { struct llist_node *pos, *t; + int cnt = 0; - llist_for_each_safe(pos, t, llnode) + llist_for_each_safe(pos, t, llnode) { free_one(pos, percpu); + cnt++; + } + return cnt; } static void __free_rcu(struct rcu_head *head)