bpf: use __GFP_COMP while allocating page

Helper bpg_msg_pull_data() can allocate multiple pages while
linearizing multiple scatterlist elements into one shared page.
However, if the shared page has size > PAGE_SIZE, using
copy_page_to_iter() causes below warning.

e.g.
[ 6367.019832] WARNING: CPU: 2 PID: 7410 at lib/iov_iter.c:825
page_copy_sane.part.8+0x0/0x8

To avoid above warning, use __GFP_COMP while allocating multiple
contiguous pages.

Fixes: 015632bb30da ("bpf: sk_msg program helper bpf_sk_msg_pull_data")
Signed-off-by: Tushar Dave <tushar.n.dave@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/net/core/filter.c b/net/core/filter.c
index aecdeba..5e00f2b 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2344,7 +2344,8 @@ BPF_CALL_4(bpf_msg_pull_data,
        if (unlikely(bytes_sg_total > copy))
                return -EINVAL;
 
-       page = alloc_pages(__GFP_NOWARN | GFP_ATOMIC, get_order(copy));
+       page = alloc_pages(__GFP_NOWARN | GFP_ATOMIC | __GFP_COMP,
+                          get_order(copy));
        if (unlikely(!page))
                return -ENOMEM;
        p = page_address(page);