[PATCH] [A|B/master][SRU] Fix soft lockup on thunderx_zip driver

Paolo Pisati paolo.pisati at canonical.com
Tue Mar 27 10:31:52 UTC 2018

BugLink: http://bugs.launchpad.net/bugs/1755073

Enabling virtual mapped kernel stacks breaks the thunderx_zip driver. On
compression or decompression the executing CPU hangs in an endless loop. The
reason for this is the usage of __pa() by the driver that does not work for an
address that is not part of the 1:1 mapping.

== Fix ==

The attached patch fixes the driver - it's not an upstream patch (hence i marked
it as SAUCE) and it came from Cavim itself.

To reproduce the bug (and test the fixed kernel):

# modprobe zram
# echo 1 > /sys/block/zram0/reset
# echo deflate > /sys/block/zram0/comp_algorithm
# echo 128M > /sys/block/zram0/disksize
# mkfs.ext4 -F /dev/zram0

if the above sequence completes, your kernel is good.

== Regression Potential ==

The patch affects only the thunderx_zip driver (that is already in a completely
broken state), so the regression potential is low.

Tested on a thunderx board, proposing for artful/master and bionic/master.

Jan Glauber (1):
  SAUCE: crypto: thunderx_zip: Fix fallout from CONFIG_VMAP_STACK

 drivers/crypto/cavium/zip/zip_crypto.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)


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