[PATCH bpf] devmap: Use GFP_KERNEL for xdp bulk queue allocation

[PATCH bpf] devmap: Use GFP_KERNEL for xdp bulk queue allocation

[NOMURA JUNICHI(野村 淳一)]

The devmap bulk queue is allocated with GFP_ATOMIC and the allocation may
fail if there is no available space in existing percpu pool.

Since commit 75ccae62cb8d42 ("xdp: Move devmap bulk queue into struct net_device")
moved the bulk queue allocation to NETDEV_REGISTER callback, whose context
is allowed to sleep, use GFP_KERNEL instead of GFP_ATOMIC to let percpu
allocator extend the pool when needed and avoid possible failure of netdev
registration.

As the required alignment is natural, we can simply use alloc_percpu().

Signed-off-by: Jun'ichi Nomura <junichi.nomura@nec.com>

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index f6e9c68afdd4..f4d3fe8e0652 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -803,8 +803,7 @@ static int dev_map_notification(struct notifier_block *notifier,
 
 		/* will be freed in free_netdev() */
 		netdev->xdp_bulkq =
-			__alloc_percpu_gfp(sizeof(struct xdp_dev_bulk_queue),
-					   sizeof(void *), GFP_ATOMIC);
+			alloc_percpu(struct xdp_dev_bulk_queue);
 		if (!netdev->xdp_bulkq)
 			return NOTIFY_BAD;
 

Re: [PATCH bpf] devmap: Use GFP_KERNEL for xdp bulk queue allocation

[Daniel Borkmann]

On 2/9/21 9:24 AM, NOMURA JUNICHI(野村　淳一) wrote:
> The devmap bulk queue is allocated with GFP_ATOMIC and the allocation may
> fail if there is no available space in existing percpu pool.
> 
> Since commit 75ccae62cb8d42 ("xdp: Move devmap bulk queue into struct net_device")
> moved the bulk queue allocation to NETDEV_REGISTER callback, whose context
> is allowed to sleep, use GFP_KERNEL instead of GFP_ATOMIC to let percpu
> allocator extend the pool when needed and avoid possible failure of netdev
> registration.
> 
> As the required alignment is natural, we can simply use alloc_percpu().
> 
> Signed-off-by: Jun'ichi Nomura <junichi.nomura@nec.com>

Applied, thanks!