[PATCH 4.18 092/135] bpf: use __GFP_COMP while allocating page

Greg Kroah-Hartman
2018-10-16T17:14:26Z

From: Tushar Dave <tushar.n.dave@oracle.com>

[ Upstream commit 4c3d795cb012a378855543a775408fba1ccff6f2 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/filter.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2334,7 +2334,8 @@ 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);