linux-kernel - Re: [PATCH] vsock/virtio: use GFP

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Message-ID: <20241003-inkompatibel-bankraub-c63b9ca506f5@brauner>
Date: Thu, 3 Oct 2024 11:09:16 +0200
From: Christian Brauner <brauner@...nel.org>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: linux-kernel@...r.kernel.org, Stefano Garzarella <sgarzare@...hat.com>, 
	Luigi Leonardi <luigi.leonardi@...look.com>, Jason Wang <jasowang@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez <eperezma@...hat.com>, 
	Stefan Hajnoczi <stefanha@...hat.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Marco Pinna <marco.pinn95@...il.com>, 
	virtualization@...ts.linux.dev, kvm@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] vsock/virtio: use GFP_ATOMIC under RCU read lock

On Wed, Oct 02, 2024 at 09:41:42AM GMT, Michael S. Tsirkin wrote:
> virtio_transport_send_pkt in now called on transport fast path,
> under RCU read lock. In that case, we have a bug: virtio_add_sgs
> is called with GFP_KERNEL, and might sleep.
> 
> Pass the gfp flags as an argument, and use GFP_ATOMIC on
> the fast path.
> 
> Link: https://lore.kernel.org/all/hfcr2aget2zojmqpr4uhlzvnep4vgskblx5b6xf2ddosbsrke7@nt34bxgp7j2x
> Fixes: efcd71af38be ("vsock/virtio: avoid queuing packets when intermediate queue is empty")
> Reported-by: Christian Brauner <brauner@...nel.org>
> Cc: Stefano Garzarella <sgarzare@...hat.com>
> Cc: Luigi Leonardi <luigi.leonardi@...look.com>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> ---
> 
> Lightly tested. Christian, could you pls confirm this fixes the problem
> for you? Stefano, it's a holiday here - could you pls help test!
> Thanks!

Thank you for the quick fix:
Reviewed-by: Christian Brauner <brauner@...nel.org>