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

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Message-ID: <eb3a9746-83a0-8271-6bd6-867ecfa49aad@redhat.com>
Date: Fri, 2 Jan 2026 14:46:44 +0100 (CET)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Askar Safin <safinaskar@...il.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



On Thu, 11 Dec 2025, Askar Safin wrote:

> Mikulas Patocka <mpatocka@...hat.com>:
> > So, this is what happened to you - the machine runs out of memory, it 
> > needs to swap out some pages, dm-crypt encrypts the pages and generates 
> > write bios, the write bios are directed to the loop device, the loop 
> > device directs them to the filesystem, the filesystem attempts to allocate 
> > more memory => deadlock.
> 
> Does similar thing happen in my case? I. e. swap on top of dm-integrity on
> top of partition? Is my use case supported? (I'm not talking about
> hibernation now, just about swap.)
> 
> -- 
> Askar Safin

Hi

Dm integrity doesn't need to allocate memory when processing I/O requests 
(it reserves some memory using mempools). So, dm-integrity on the top of a 
partition should be safe.

Mikulas