arm64: unhandled level 3 permission fault on ltp mmap16 test

[Suzuki.Poulose@arm.com (Suzuki K Poulose)]

On 19/05/16 06:34, fixed-term.Oleksij.Rempel wrote:
> Hallo all,
>
> if i run latest ltp tests on any of latest kernel version i get
> fallowing warning:
>
> root at rcar1:/opt/ltp# dmesg
> root at rcar1:/opt/ltp# ./testcases/bin/mmap16
> mmap16      0  TINFO  :  Found free device '/dev/loop0'
> mmap16      0  TINFO  :  Formatting /dev/loop0 with ext4 opts='-b 1024'
> extra opts='10240'
> mke2fs 1.43-WIP (15-Mar-2016)
> [  889.736679] EXT4-fs (loop0): mounted filesystem with ordered data
> mode. Opts: nodelalloc
> [  889.843995] mmap16[2164]: unhandled level 3 permission fault (7) at
> 0x7f8397d400, esr 0x9200004f

IIRC, this is expected. The test performs the access on purpose. It spawns
a child which does this access and expects SIGBUS to be delivered to it. The
parent makes sure that the SIGBUS is delivered to by wait()-ing for it.

See :
                 /*
                  * If child process was killed by SIGBUS, bug is not reproduced.
                  */
                 if (!WIFSIGNALED(status) || WTERMSIG(status) != SIGBUS) {
                         tst_brkm(TBROK | TERRNO, cleanup,
                                  "child process terminate unexpectedly");
                 }

>
> Can some one please help me to understand this? If i see it correctly,
> some thing wrong happened by level 3 address translation. But i have no
> idea how to solve it (if it should be solved)

On arm64 we print unhandled faults to give enough information to debug the
problem, which is why you see those messages in dmesg.

So, you can ignore those messages as long as the faults are generated by
mmap16 and thetest reports success.

Suzuki