Re: [PATCH bpf-next v2 01/35] bpf: memcg-based memory accounting for bpf progs

On Mon, Jul 27, 2020 at 03:11:42PM -0700, Song Liu wrote:

On Mon, Jul 27, 2020 at 12:20 PM Roman Gushchin [off-list ref] wrote:

quoted

Include memory used by bpf programs into the memcg-based accounting.
This includes the memory used by programs itself, auxiliary data
and statistics.

Signed-off-by: Roman Gushchin <redacted>
---
 kernel/bpf/core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index bde93344164d..daab8dcafbd4 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c

@@ -77,7 +77,7 @@ void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, uns

 struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flags)
 {
-       gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags;
+       gfp_t gfp_flags = GFP_KERNEL_ACCOUNT | __GFP_ZERO | gfp_extra_flags;
        struct bpf_prog_aux *aux;
        struct bpf_prog *fp;

@@ -86,7 +86,7 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag
        if (fp == NULL)
                return NULL;

-       aux = kzalloc(sizeof(*aux), GFP_KERNEL | gfp_extra_flags);
+       aux = kzalloc(sizeof(*aux), GFP_KERNEL_ACCOUNT | gfp_extra_flags);
        if (aux == NULL) {
                vfree(fp);
                return NULL;

@@ -104,7 +104,7 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag

 struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
 {
-       gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags;
+       gfp_t gfp_flags = GFP_KERNEL_ACCOUNT | __GFP_ZERO | gfp_extra_flags;
        struct bpf_prog *prog;
        int cpu;

@@ -217,7 +217,7 @@ void bpf_prog_free_linfo(struct bpf_prog *prog)
 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
                                  gfp_t gfp_extra_flags)
 {
-       gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags;
+       gfp_t gfp_flags = GFP_KERNEL_ACCOUNT | __GFP_ZERO | gfp_extra_flags;
        struct bpf_prog *fp;
        u32 pages, delta;
        int ret;
--

Hi Song!

Thank you for looking into the patchset!

Do we need similar changes in

bpf_prog_array_copy()
bpf_prog_alloc_jited_linfo()
bpf_prog_clone_create()

and maybe a few more?

I've tried to follow the rlimit-based accounting, so those objects which were
skipped are mostly skipped now and vice versa. The main reason for that is
simple: I don't know many parts of bpf code well enough to decide whether
we need accounting or not.

In general with memcg-based accounting we can easily cover places which were
not covered previously: e.g. the memory used by the verifier. But I guess it's
better to do it case-by-case.

But if you're aware of any big objects which should be accounted for sure,
please, let me know.

Thanks!