From: Alexei Starovoitov <ast@kernel.org>
Date: Wed, 5 Jul 2023 20:34:42 -0700
Subject: bpf: Allow reuse from waiting_for_gp_ttrace list.
Patch-mainline: v6.6-rc1
Git-commit: 04fabf00b4d3aff5d010ecb617001814e409e24a
References: jsc#PED-6811
alloc_bulk() can reuse elements from free_by_rcu_ttrace.
Let it reuse from waiting_for_gp_ttrace as well to avoid unnecessary kmalloc().
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230706033447.54696-10-alexei.starovoitov@gmail.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
kernel/bpf/memalloc.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -212,6 +212,15 @@ static void alloc_bulk(struct bpf_mem_ca
if (i >= cnt)
return;
+ for (; i < cnt; i++) {
+ obj = llist_del_first(&c->waiting_for_gp_ttrace);
+ if (!obj)
+ break;
+ add_obj_to_free_list(c, obj);
+ }
+ if (i >= cnt)
+ return;
+
memcg = get_memcg(c);
old_memcg = set_active_memcg(memcg);
for (; i < cnt; i++) {
@@ -295,12 +304,7 @@ static void do_call_rcu_ttrace(struct bp
WARN_ON_ONCE(!llist_empty(&c->waiting_for_gp_ttrace));
llist_for_each_safe(llnode, t, llist_del_all(&c->free_by_rcu_ttrace))
- /* There is no concurrent __llist_add(waiting_for_gp_ttrace) access.
- * It doesn't race with llist_del_all either.
- * But there could be two concurrent llist_del_all(waiting_for_gp_ttrace):
- * from __free_rcu() and from drain_mem_cache().
- */
- __llist_add(llnode, &c->waiting_for_gp_ttrace);
+ llist_add(llnode, &c->waiting_for_gp_ttrace);
if (unlikely(READ_ONCE(c->draining))) {
__free_rcu(&c->rcu_ttrace);