netdev - Re: [PATCH net v2] net: airoha: Fix schedule while atomic in airoha_ppe

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Message-ID: <20260108132218.GG345651@kernel.org>
Date: Thu, 8 Jan 2026 13:22:18 +0000
From: Simon Horman <horms@...nel.org>
To: Lorenzo Bianconi <lorenzo@...nel.org>
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, netdev@...r.kernel.org
Subject: Re: [PATCH net v2] net: airoha: Fix schedule while atomic in
 airoha_ppe_deinit()

On Mon, Jan 05, 2026 at 09:43:31AM +0100, Lorenzo Bianconi wrote:
> airoha_ppe_deinit() runs airoha_npu_ppe_deinit() in atomic context.
> airoha_npu_ppe_deinit routine allocates ppe_data buffer with GFP_KERNEL
> flag. Rely on rcu_replace_pointer in airoha_ppe_deinit routine in order
> to fix schedule while atomic issue in airoha_npu_ppe_deinit() since we
> do not need atomic context there.

Hi Lorenzo,

If I understand things correctly the key problem here is that
an allocation with GFP_KERNEL implies GFP_RECLAIM and thus may sleep.
But RCU read-side critical sections are not allowed to sleep in non-RT
kernels.

If so, I think it would be clearer to describe the problem along those
lines. But maybe it is just me.

> 
> Fixes: 00a7678310fe3 ("net: airoha: Introduce flowtable offload support")
> Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
> ---
> Changes in v2:
> - Update commit log.
> - Link to v1: https://lore.kernel.org/r/20251223-airoha-fw-ethtool-v1-1-1dbd1568c585@kernel.org

...