[dm-devel] [4.4, 4.5, 4.6] Regression: encrypted swap (dm-crypt) freezes system while under memory pressure and swapping

[Matthias Dahl]

Hello Ondrej...

Thanks for taking the time.

On 27/04/16 17:13, Ondrej Kozina wrote:

> I observe that putting swap on top of dm-crypt (tested in current 4.6-rc
> kernel) have some unexpected side effects. Most notably it seems to me
> that oom killer joins the party quite prematurely even when there
> remains plenty of free swap space (almost all). But I didn't experience
> any permanent system freeze or crash. Just, let us dig deeper for a
> while...

Yes, 4.6-rc* behaves different from 4.4.x and >= 4.5-rc3 but it still
does not work correctly at all. You may want to try the little test
program I created and attached. I used it quite a lot to stress the system.

With that, you should have no problem seeing the described behavior on
the affected kernels. You may have to adjust the sleep a bit, depending
on your machine, though.

If there is anything else I can do to help, please let me know.

Have a nice day,
Matthias

-- 
Dipl.-Inf. (FH) Matthias Dahl | Software Engineer | binary-island.eu
 services: custom software [desktop, mobile, web], server administration
-------------- next part --------------
A non-text attachment was scrubbed...
Name: main.cpp
Type: text/x-c++src
Size: 849 bytes
Desc: not available
URL: <http://listman.redhat.com/archives/dm-devel/attachments/20160428/0de39b1b/attachment.bin>