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Date: Thu, 3 Apr 2025 15:31:29 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?= <toke@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>, Jesper Dangaard Brouer
 <hawk@kernel.org>, Saeed Mahameed <saeedm@nvidia.com>, Leon Romanovsky
 <leon@kernel.org>, Tariq Toukan <tariqt@nvidia.com>, Andrew Lunn
 <andrew+netdev@lunn.ch>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, Ilias Apalodimas <ilias.apalodimas@linaro.org>, Simon
 Horman <horms@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Mina
 Almasry <almasrymina@google.com>, Yonglong Liu <liuyonglong@huawei.com>,
 Yunsheng Lin <linyunsheng@huawei.com>, Pavel Begunkov
 <asml.silence@gmail.com>, Matthew Wilcox <willy@infradead.org>,
 netdev@vger.kernel.org, bpf@vger.kernel.org, linux-rdma@vger.kernel.org,
 linux-mm@kvack.org, Qiuling Ren <qren@redhat.com>, Yuying Ma
 <yuma@redhat.com>
Subject: Re: [PATCH net-next v6 2/2] page_pool: Track DMA-mapped pages and
 unmap them when destroying the pool
Message-ID: <20250403153129.013a7bdd@kernel.org>
In-Reply-To: <20250401-page-pool-track-dma-v6-2-8b83474870d4@redhat.com>
References: <20250401-page-pool-track-dma-v6-0-8b83474870d4@redhat.com>
	<20250401-page-pool-track-dma-v6-2-8b83474870d4@redhat.com>
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On Tue, 01 Apr 2025 11:27:19 +0200 Toke H=C3=B8iland-J=C3=B8rgensen wrote:
> +	if (err) {
> +		WARN_ONCE(1, "couldn't track DMA mapping, please report to netdev@");
>  		goto unmap_failed;

FWIW I second Pavel's concern about the warning being too drastic.
I have the feeling Meta's fleet will hit this.
How about WARN_ONCE(err !=3D -ENOMEM, ... ? I presume you care mostly
about the array filling up so -EBUSY

> +	}
> =20
> +	if (page_pool_set_dma_addr_netmem(netmem, dma)) {
> +		WARN_ONCE(1, "unexpected DMA address, please report to netdev@");
> +		goto unmap_failed;
> +	}

I think this is ever so slightly leaking the id, if it ever happens?