linux-kernel - [PATCH 4.18 092/135] bpf: use __GFP

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Date:   Tue, 16 Oct 2018 19:05:22 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tushar Dave <tushar.n.dave@...cle.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.18 092/135] bpf: use __GFP_COMP while allocating page

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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);