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---Problem Description---
When run as normal user, 'perf record ls' fails with:

  Perf session creation failed.

The command runs successfully when run as root.
  
---uname output---
Linux ubuntu 3.16.0-16-generic #22-Ubuntu SMP Wed Sep 17 18:45:43 UTC 2014 ppc64le ppc64le ppc64le GNU/Linux
 
Machine Type = POWER8E pvr 004b 0201 

> Maynard,
> 
> Can you check if /proc/sys/kernel/kptr_restrict has 1 in it on your
> system ? 

Yes, the value is '1'.

> 
> On my system it does have 1 and I can repro. Following seems to
> fix:
>     echo 0 > /proc/sys/kernel/kptr_restrict

Yes, changing it to '0' does "fix" it, although that shouldn't be
necessary, as you know.  So something is broken.

I am able to repro with 3.17.0-rc4 based mainline perf tool.

I suspect that the change in behavior was introduced unintentionally by
this upstream commit. machine__create_kernel_maps() now calls
 machine__get_kernel_start_addr() which checks the kptr_restrict state.

---

commit a93f0e551af9e194db38bfe16001e17a3a1d189a
Author: Simon Que <sque@xxxxxxxxxxxx>
Date:   Mon Jun 16 11:32:09 2014 -0700

    perf symbols: Get kernel start address by symbol name

This is being fixed by a recent upstream commit:

    https://lkml.org/lkml/2014/9/27/26

Will Ubuntu pick that fix up automatically ?

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Confirmed


** Tags: architecture-ppc64le bugnameltc-116381 severity-medium targetmilestone-inin---
-- 
'perf record' fails with "Perf session creation failed"
https://bugs.launchpad.net/bugs/1375441
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