bpf: Include verifier memory allocations in memcg statistics

This commit adds __GFP_ACCOUNT flag to verifier induced memory
allocations. The intent is to account for all allocations reachable
from BPF_PROG_LOAD command, which is needed to track verifier memory
consumption in veristat. This includes allocations done in verifier.c,
and some allocations in btf.c, functions in log.c do not allocate.

There is also a utility function bpf_memcg_flags() which selectively
adds GFP_ACCOUNT flag depending on the `cgroup.memory=nobpf` option.
As far as I understand [1], the idea is to remove bpf_prog instances
and maps from memcg accounting as these objects do not strictly belong
to cgroup, hence it should not apply here.

(btf_parse_fields() is reachable from both program load and map
 creation, but allocated record is not persistent as is freed as soon
 as map_check_btf() exits).

[1] https://lore.kernel.org/all/20230210154734.4416-1-laoar.shao@gmail.com/

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250613072147.3938139-2-eddyz87@gmail.com

1 files changed, 8 insertions, 7 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 1d2cf898e21e..682acb1ed234 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3443,7 +3443,8 @@ btf_find_graph_root(const struct btf *btf, const struct btf_type *pt,
 	node_field_name = strstr(value_type, ":");
 	if (!node_field_name)
 		return -EINVAL;
-	value_type = kstrndup(value_type, node_field_name - value_type, GFP_KERNEL | __GFP_NOWARN);
+	value_type = kstrndup(value_type, node_field_name - value_type,
+			      GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
 	if (!value_type)
 		return -ENOMEM;
 	id = btf_find_by_name_kind(btf, value_type, BTF_KIND_STRUCT);
@@ -3958,7 +3959,7 @@ struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type
 	/* This needs to be kzalloc to zero out padding and unused fields, see
 	 * comment in btf_record_equal.
 	 */
-	rec = kzalloc(struct_size(rec, fields, cnt), GFP_KERNEL | __GFP_NOWARN);
+	rec = kzalloc(struct_size(rec, fields, cnt), GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
 	if (!rec)
 		return ERR_PTR(-ENOMEM);
 
@@ -9019,7 +9020,7 @@ static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands,
 		bpf_free_cands_from_cache(*cc);
 		*cc = NULL;
 	}
-	new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL);
+	new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL_ACCOUNT);
 	if (!new_cands) {
 		bpf_free_cands(cands);
 		return ERR_PTR(-ENOMEM);
@@ -9027,7 +9028,7 @@ static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands,
 	/* strdup the name, since it will stay in cache.
 	 * the cands->name points to strings in prog's BTF and the prog can be unloaded.
 	 */
-	new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL);
+	new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL_ACCOUNT);
 	bpf_free_cands(cands);
 	if (!new_cands->name) {
 		kfree(new_cands);
@@ -9111,7 +9112,7 @@ bpf_core_add_cands(struct bpf_cand_cache *cands, const struct btf *targ_btf,
 			continue;
 
 		/* most of the time there is only one candidate for a given kind+name pair */
-		new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL);
+		new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL_ACCOUNT);
 		if (!new_cands) {
 			bpf_free_cands(cands);
 			return ERR_PTR(-ENOMEM);
@@ -9228,7 +9229,7 @@ int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
 	/* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5"
 	 * into arrays of btf_ids of struct fields and array indices.
 	 */
-	specs = kcalloc(3, sizeof(*specs), GFP_KERNEL);
+	specs = kcalloc(3, sizeof(*specs), GFP_KERNEL_ACCOUNT);
 	if (!specs)
 		return -ENOMEM;
 
@@ -9253,7 +9254,7 @@ int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
 			goto out;
 		}
 		if (cc->cnt) {
-			cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL);
+			cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL_ACCOUNT);
 			if (!cands.cands) {
 				err = -ENOMEM;
 				goto out;