[dm-devel] CPU hotplug issue in dm-crypt driver

[mittals at codeaurora.org]

Hi,

We are using dm-crypt driver to encrypt Android Phone on a 2 core target.
We saw random failures (kernel panics) in scatterwalk code when we were
trying to bring secondary cpu online and offline randomly.

I looked into the dm-crypt driver(drivers/md/dm-crypt.c) and put a hack in
the kcryptd_queue_crypt function to acquire hotplug lock (using
get_online_cpus()), just before adding new work in work queue and release
this lock (using put_online_cpus) after completing work in kcryptd_crypt
function.
With this i didn't see any issue during encryption.

So my questions are -

1) Is it a know problem that there is some issue with dm-crypt driver with
cpu hotplug?

2) If yes, then can someone suggest me a cleaner way to resolve this issue?

Thanks in advance!

--Shashank

Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.