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

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] [day] [month] [year] [list]

Message-ID: <81fc481c-5421-42ad-a13a-b9e9c6ededb6@linux.dev>
Date: Fri, 25 Apr 2025 09:40:53 -0700
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Jordan Rife <jordan@...fe.io>,
 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>, 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

On 4/24/25 8:39 AM, Jordan Rife wrote:
>> 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.

No strong opinion on how many retries on GFP_USER, so no objection on trying 
GFP_USER only once and then retry one last time with GFP_NOWAIT|__GFP_NOWARN.

> 
>> 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