linux-kernel - [PATCH AUTOSEL 4.18 30/48] bpf: use __GFP

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Message-Id: <20181005161424.20521-30-sashal@kernel.org>
Date:   Fri,  5 Oct 2018 12:14:06 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Tushar Dave <tushar.n.dave@...cle.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 30/48] bpf: use __GFP_COMP while allocating page

From: Tushar Dave <tushar.n.dave@...cle.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@...cle.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 net/core/filter.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 9dfd145eedcc..e361583e2378 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2328,7 +2328,8 @@ BPF_CALL_4(bpf_msg_pull_data,
 	if (unlikely(copy < end - start))
 		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);
-- 
2.17.1