Since SLOB was removed and since commit 6c6c47b063b5 ("mm, slab: call kvfree_rcu_barrier() from kmem_cache_destroy()"), it is not necessary to use call_rcu when the callback only performs kmem_cache_free. Use kfree_rcu() directly. The changes were done using the following Coccinelle semantic patch. This semantic patch is designed to ignore cases where the callback function is used in another way. // <smpl> #spatch --all-includes --include-headers @r@ expression e; local idexpression e2; identifier cb,f,g; position p; @@ ( call_rcu(...,e2) | call_rcu(&e->f,cb@p) | call_rcu(&e->f.g,cb@p) ) @r1@ type T,T1; identifier x,r.cb; @@ cb(...) { ( kmem_cache_free(...); | T x = ...; kmem_cache_free(...,(T1)x); | T x; x = ...; kmem_cache_free(...,(T1)x); ) } @s depends on r1@ position p != r.p; identifier r.cb; @@ cb@p @script:ocaml@ cb << r.cb; p << s.p; @@ Printf.eprintf "Other use of %s at %s:%d\n" cb (List.hd p).file (List.hd p).line @depends on r1 && !s@ expression e; identifier r.cb,f,g; position r.p; @@ ( - call_rcu(&e->f,cb@p) + kfree_rcu(e,f) | - call_rcu(&e->f.g,cb@p) + kfree_rcu(e,f.g) ) @r1a depends on !s@ type T,T1; identifier x,r.cb; @@ - cb(...) { ( - kmem_cache_free(...); | - T x = ...; - kmem_cache_free(...,(T1)x); | - T x; - x = ...; - kmem_cache_free(...,(T1)x); ) - } @r2 depends on !r1@ identifier r.cb; @@ cb(...) { ... } @script:ocaml depends on !r1 && !r2@ cb << r.cb; @@ Printf.eprintf "need definition for %s\n" cb // </smpl> --- arch/powerpc/kvm/book3s_mmu_hpte.c | 8 ------ block/blk-ioc.c | 9 ------ drivers/net/wireguard/allowedips.c | 9 +----- fs/ecryptfs/dentry.c | 8 ------ fs/nfsd/nfs4state.c | 9 ------ kernel/time/posix-timers.c | 9 ------ net/batman-adv/translation-table.c | 47 ++---------------------------------- net/bridge/br_fdb.c | 9 ------ net/can/gw.c | 13 ++------- net/ipv4/fib_trie.c | 8 ------ net/ipv4/inetpeer.c | 9 +----- net/ipv6/ip6_fib.c | 9 ------ net/ipv6/xfrm6_tunnel.c | 8 ------ net/kcm/kcmsock.c | 10 ------- net/netfilter/nf_conncount.c | 10 ------- net/netfilter/nf_conntrack_expect.c | 10 ------- net/netfilter/xt_hashlimit.c | 9 ------ 17 files changed, 23 insertions(+), 171 deletions(-)