Date: Wed, 11 Sep 2013 07:55:03 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: linux-kernel@vger.kernel.org,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Andi Kleen <ak@linux.intel.com>, David Ahern <dsahern@gmail.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@elte.hu>,
        Jiri Olsa <jolsa@redhat.com>, Mike Galbraith <efault@gmx.de>,
        Namhyung Kim <namhyung@gmail.com>, Paul Mackerras <paulus@samba.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Stephane Eranian <eranian@google.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [GIT PULL 0/5] perf/urgent fixes
Message-ID: <20130911055503.GB15395@gmail.com>
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Hm, after this pull request, 'perf top' started misbehaving on older 
kernels:
             
             ┌─Error:────────────────────────────────────────────────────────────────────────────────────┐
             │The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cycles).  │
             │/bin/dmesg may provide additional information.                                             │
             │No CONFIG_PERF_EVENTS=y kernel support configured?                                         │

But:

 $ cat /proc/sys/kernel/perf_event_paranoid 
 -1

The syscall really fails:

 16645 perf_event_open(0x1eb7f00, 0xffffffff, 0, 0xffffffff, 0) = -1 EINVAL (Invalid argument)
 16645 perf_event_open(0x1eb7f00, 0xffffffff, 0, 0xffffffff, 0) = -1 EINVAL (Invalid argument)
 16645 perf_event_open(0x1eb7f00, 0xffffffff, 0, 0xffffffff, 0) = -1 EINVAL (Invalid argument)

Caused by:

 575a9aab0f85 perf tools: Add attr->mmap2 support

We must not force mmap2 support to be present on the kernel side - new 
perf top should work on older kernels just as well.

So I've unpulled the tree for now.

Thanks,

	Ingo
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