netdev - [PATCH bpf-next] bpf: use kvmalloc in map_lookup

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Message-Id: <20210816164832.1743675-1-sdf@google.com>
Date:   Mon, 16 Aug 2021 09:48:32 -0700
From:   Stanislav Fomichev <sdf@...gle.com>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf-next] bpf: use kvmalloc in map_lookup_elem

Use kvmalloc/kvfree for temporary value when looking up a map.
kmalloc might not be sufficient for percpu maps where the value is big.

Can be reproduced with netcnt test on qemu with "-smp 255".

Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
 kernel/bpf/syscall.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 9a2068e39d23..ae0b1c1c8ece 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1076,7 +1076,7 @@ static int map_lookup_elem(union bpf_attr *attr)
 	value_size = bpf_map_value_size(map);
 
 	err = -ENOMEM;
-	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
+	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
 	if (!value)
 		goto free_key;
 
@@ -1091,7 +1091,7 @@ static int map_lookup_elem(union bpf_attr *attr)
 	err = 0;
 
 free_value:
-	kfree(value);
+	kvfree(value);
 free_key:
 	kfree(key);
 err_put:
-- 
2.33.0.rc1.237.g0d66db33f3-goog