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

[Mikulas Patocka <mpatocka@redhat.com>]

On Thu, 11 Dec 2025, Askar Safin wrote:

> Mikulas Patocka <mpatocka@redhat.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