netdev - Re: [PATCH v5 bpf-next 2/6] bpf: udp: Make sure iter->batch always contains a full bucket snapshot

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Message-ID: <kjcasjtjil6br6qton7uz52ql25udddmzbraaw6qmjadbqj5xm@3o5c2rgdt5bt>
Date: Thu, 24 Apr 2025 08:39:21 -0700
From: Jordan Rife <jordan@...fe.io>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Network Development <netdev@...r.kernel.org>, 
	bpf <bpf@...r.kernel.org>, Aditi Ghag <aditi.ghag@...valent.com>, 
	Daniel Borkmann <daniel@...earbox.net>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	Willem de Bruijn <willemdebruijn.kernel@...il.com>, Kuniyuki Iwashima <kuniyu@...zon.com>
Subject: Re: [PATCH v5 bpf-next 2/6] bpf: udp: Make sure iter->batch always
 contains a full bucket snapshot

> It looks like overdesign.
> I think it would be much simpler to do GFP_USER once,

Martin expressed a preference for retrying GFP_USER, so I'll let him
chime in here, but I'm fine the simpler approach. There were some
concerns about maximizing the chances that allocation succeeds, but
this situation should be be rare anyway, so yeah retries are probably
overkill.

> grab the lock and follow with GFP_NOWAIT|__GFP_NOWARN.
> GFP_ATOMIC will deplete memory reserves.
> bpf iterator is certainly not a critical operation, so use GFP_NOWAIT.

Yeah, GFP_NOWAIT makes sense. Will do.

Jordan