linux-kernel - Re: [RFC PATCH] mm: net: disable kswapd for high-order network buffer allocation

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Message-ID: <aO11jqD6jgNs5h8K@casper.infradead.org>
Date: Mon, 13 Oct 2025 22:56:30 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Barry Song <21cnbao@...il.com>
Cc: netdev@...r.kernel.org, linux-mm@...ck.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, Barry Song <v-songbaohua@...o.com>,
	Jonathan Corbet <corbet@....net>,
	Eric Dumazet <edumazet@...gle.com>,
	Kuniyuki Iwashima <kuniyu@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Willem de Bruijn <willemb@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Simon Horman <horms@...nel.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>,
	Brendan Jackman <jackmanb@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>, Zi Yan <ziy@...dia.com>,
	Yunsheng Lin <linyunsheng@...wei.com>,
	Huacai Zhou <zhouhuacai@...o.com>
Subject: Re: [RFC PATCH] mm: net: disable kswapd for high-order network
 buffer allocation

On Mon, Oct 13, 2025 at 06:16:36PM +0800, Barry Song wrote:
> On phones, we have observed significant phone heating when running apps
> with high network bandwidth. This is caused by the network stack frequently
> waking kswapd for order-3 allocations. As a result, memory reclamation becomes
> constantly active, even though plenty of memory is still available for network
> allocations which can fall back to order-0.

I think we need to understand what's going on here a whole lot more than
this!

So, we try to do an order-3 allocation.  kswapd runs and ... succeeds in
creating order-3 pages?  Or fails to?

If it fails, that's something we need to sort out.

If it succeeds, now we have several order-3 pages, great.  But where do
they all go that we need to run kswapd again?