Re: [PATCH net v3] mptcp: only set DATA_FIN when a mapping is present

[Matthieu Baerts]

On 10/07/2026 19:17, Michael Bommarito wrote:
> On Fri, Jul 10, 2026 at 12:19 PM Matthieu Baerts <matttbe@xxxxxxxxxx> wrote:
>>
>> I tried to reproduce it on my side using packetdrill-mptcp [1], but I
>> was not able to test with KMSAN: my kernel boot, but is stuck when KMSAN
>> is enabled... By chance, if you can try this reproducer on your side,
>> with and without your patched kernel, that would be great :)
>>
>> [1] https://github.com/multipath-tcp/packetdrill/pull/203
> 
> Can you try with more RAM and make sure that you have these set too?
> 
> CONFIG_CRYPTO_USER_API=y
> CONFIG_CRYPTO_USER_API_HASH=y

Thank you for the suggestion. Yes, I did use more RAM (just tried with
8G just to be sure), and with the CRYPTO_USER_API (needed for
packetdrill), but the VM stalls at boot time:

  Starting KernelMemorySanitizer
  ATTENTION: KMSAN is a debugging tool! Do not use it on production
machines!

I didn't investigate more, but I'm using KMSAN on another similar
machine with syzkaller without issues.
> I was able to get your PR #203 test to trigger after using -m 8G +
> AF_ALG under vng

Nice, thank you for having checked that! I guess I can merge this PR then.

Cheers,
Matt
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