On 6/9/25 3:45 PM, Stanislav Fomichev wrote:
On 06/08, Yonghong Song wrote:
The bpf selftest xdp_adjust_tail/xdp_adjust_frags_tail_grow failed on
arm64 with 64KB page:
xdp_adjust_tail/xdp_adjust_frags_tail_grow:FAIL
In bpf_prog_test_run_xdp(), the xdp->frame_sz is set to 4K, but later on
when constructing frags, with 64K page size, the frag data_len could
be more than 4K. This will cause problems in bpf_xdp_frags_increase_tail().
Limiting the data_len to be 4K for each frag fixed the above test failure.
Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
---
net/bpf/test_run.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index aaf13a7d58ed..5529ec007954 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -1214,6 +1214,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
u32 repeat = kattr->test.repeat;
struct netdev_rx_queue *rxqueue;
struct skb_shared_info *sinfo;
+ const u32 frame_sz = 4096;
struct xdp_buff xdp = {};
int i, ret = -EINVAL;
struct xdp_md *ctx;
@@ -1255,7 +1256,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
headroom -= ctx->data;
}
[..]
- max_data_sz = 4096 - headroom - tailroom;
+ max_data_sz = frame_sz - headroom - tailroom;
I wonder whether we should do s/4096/PAGE_SIZE/ here instead. Have you
tried that? If we are on a 64K page arch, we should not try to preserve
4K page limits.
The user space test_run input looks like below (in prog_tests/xdp_adjust_tail.c):
buf = malloc(16384);
...
topts.data_in = buf;
topts.data_out = buf;
topts.data_size_in = 9000;
topts.data_size_out = 16384;
err = bpf_prog_test_run_opts(prog_fd, &topts);
Allowing s/4096/PAGE_SIZE (64K) will have the test failure for the above
user space input. I think I can increse buf size data_size_in/data_size_out
properly so in the kernel we can do s/4096/PAGE_SIZE.
