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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAGsJ_4ySSn6B+x+4zE0Ld1+AM4q-WnS0LfxzWw22oXr7n5NZ=g@mail.gmail.com>
Date: Tue, 14 Oct 2025 14:43:13 +0800
From: Barry Song <21cnbao@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: corbet@....net, davem@...emloft.net, hannes@...xchg.org, horms@...nel.org, 
	jackmanb@...gle.com, kuba@...nel.org, kuniyu@...gle.com, 
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	linyunsheng@...wei.com, mhocko@...e.com, netdev@...r.kernel.org, 
	pabeni@...hat.com, surenb@...gle.com, v-songbaohua@...o.com, vbabka@...e.cz, 
	willemb@...gle.com, zhouhuacai@...o.com, ziy@...dia.com
Subject: Re: [RFC PATCH] mm: net: disable kswapd for high-order network buffer allocation

> >
> > A problem with the existing sysctl is that it only covers the TX path;
> > for the RX path, we also observe that kswapd consumes significant power.
> > I could add the patch below to make it support the RX path, but it feels
> > like a bit of a layer violation, since the RX path code resides in mm
> > and is intended to serve generic users rather than networking, even
> > though the current callers are primarily network-related.
>
> You might have a buggy driver.

We are observing the RX path as follows:

do_softirq
    taskset_hi_action
       kalPacketAlloc
           __netdev_alloc_skb
               page_frag_alloc_align
                   __page_frag_cache_refill

This appears to be a fairly common stack.

So it is a buggy driver?

>
> High performance drivers use order-0 allocations only.
>

Do you have an example of high-performance drivers that use only order-0 memory?

Thanks
Barry