linux-kernel - Re: Hard system lock-ups when using encrypted swap and RAM is exhausted

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Message-ID: <fc1d7900-3a5f-4b31-8aa3-8c8cd317d646@redhat.com>
Date: Sun, 11 Jan 2026 14:34:22 +0100
From: Zdenek Kabelac <zkabelac@...hat.com>
To: Askar Safin <safinaskar@...il.com>, Mikulas Patocka <mpatocka@...hat.com>
Cc: adrelanos@...nix.org, arraybolt3@...il.com, cryptsetup@...ts.linux.dev,
 dm-devel@...ts.linux.dev, gmazyland@...il.com, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org
Subject: Re: Hard system lock-ups when using encrypted swap and RAM is
 exhausted

Dne 10. 01. 26 v 8:09 Askar Safin napsal(a):
> On Fri, Jan 2, 2026 at 4:47 PM Mikulas Patocka <mpatocka@...hat.com> wrote:
>> Hi
>>
>> Dm integrity doesn't need to allocate memory when processing I/O requests
> 
> Thank you for answer!
> 
> Unfortunately, my experience shows the opposite thing.
> 
> [[ TL;DR: my experience shows that dm-integrity journaled mode is buggy, and
> non-journaled mode is not. I. e. journaled mode seems to allocate memory, and
> this causes temporary (for 4 minutes) lockups (on high specced
> machine). Or maybe journaled mode has
> some another bug, which causes such lockups. They are not reproducible in
> non-journaled mode. ]]

I think it's important to decipher what and how it's blocked - I kind of 
suspect your system is not blocked on 'dm-integrity' itself - rather some 
userland app being swapped out of CPU.

You probably do need to configure your systemd-oom killer to prevent getting 
your system to it's knees - if you run your system to the moment whether it 
takes 4 minutes to run a task - there is something seriously wrong with the 
configuration - as OOM is supposed to kill userland RAM hogging task much 
earlier (possibly even your overbloated google chrome APP if it run out of 
bounds).

So I think you should also show whole device tree of your system and some more 
information - so there is even 'remote' chance trying to reproduce your scenario.

Regards

Zdenek