linux-kernel - Re: [PATCH 1/2] perf: Add munmap callback

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Message-ID: <46719ae1-7095-f3de-02fe-bc30a36ac523@linux.intel.com>
Date:   Tue, 6 Nov 2018 11:47:38 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Stephane Eranian <eranian@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...en8.de>, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/2] perf: Add munmap callback



On 11/6/2018 10:00 AM, Stephane Eranian wrote:
>>> /*
>>> * mmap 1 page at the location of the unmap page (should reuse virtual space)
>>> * This creates a continuous region built from two mmaps and
>>> potentially two different sources
>>> * especially with jitted runtimes
>>> */
>> The two mmaps are both anon. As my understanding, we cannot symbolize
>> from the anonymous address, can we?
> Can't we build the same test case using an actual file mapping (both
> mmap from the same file)?
> 

If they are from same file, both mmap have same symbolization name.
We don't need to distinguish them either.

I thought the symbolization issue can only happen when two mmaps are 
from different sources. Right?

Thanks,
Kan