From: Peter Zijlstra <peterz@infradead.org>
To: Andres Freund <andres@anarazel.de>
Cc: linux-kernel@vger.kernel.org,
Stephane Eranian <eranian@google.com>,
acme@kernel.org, jolsa@redhat.com, mingo@elte.hu,
anton@ozlabs.org, namhyung@kernel.org,
Stephane Eranian <eranian@gmail.com>
Subject: Re: perf/jit doesn't cope well with mprotect() to jit containing pages
Date: Mon, 12 Dec 2016 09:49:03 +0100 [thread overview]
Message-ID: <20161212084903.GZ3124@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161210050218.jw4bak5jf766iqpb@alap3.anarazel.de>
On Fri, Dec 09, 2016 at 09:02:18PM -0800, Andres Freund wrote:
>
> I presume the increasing MMAP2 size is triggered by the consecutive
> pages being represented as a single page-range in the kernel?
Yes, we print struct vm_area_struct based information, if vmas get
merged, that shows.
> If I, to work around such consecutive pages, force another page to be
> mmap()ed inbetween, and avoid using MAP_ANONYMOUS, the problem also goes
> away.
This would indeed inhibit vma merging.
> Am I doing something wrong, or is there a bug here?
Expected behaviour afaict
> BTW, it's also a bit weird that those MMAP2 records triggered by
> mprotect/mmap, have prot set to 0...
Yes, mprotect() does: vma->vm_flags = newflags; before calling
perf_event_mmap(vma); which then looks at VM_{READ,WRITE,EXEC} bits in
that word to generate the prot value.
So that being 0 is a bit weird.
next prev parent reply other threads:[~2016-12-12 8:49 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-10 5:02 perf/jit doesn't cope well with mprotect() to jit containing pages Andres Freund
2016-12-12 8:49 ` Peter Zijlstra [this message]
2016-12-12 9:01 ` Andres Freund
2016-12-12 9:28 ` Peter Zijlstra
2017-01-26 1:25 ` Andres Freund
2017-01-26 22:15 ` Peter Zijlstra
2017-01-26 23:04 ` Andres Freund
2017-01-30 11:52 ` [tip:perf/core] perf/core: Fix PERF_RECORD_MMAP2 prot/flags for anonymous memory tip-bot for Peter Zijlstra
2017-01-26 20:32 ` perf/jit doesn't cope well with mprotect() to jit containing pages Stephane Eranian
2017-01-26 21:00 ` Andres Freund
2017-01-26 21:17 ` Stephane Eranian
2017-01-26 21:22 ` Andres Freund
2017-01-26 21:34 ` Stephane Eranian
2017-01-26 21:51 ` Andres Freund
2017-01-26 22:19 ` Peter Zijlstra
2017-01-26 22:26 ` Stephane Eranian
2017-01-26 22:38 ` Andres Freund
2017-01-26 22:51 ` Stephane Eranian
2017-01-26 23:09 ` Andres Freund
2017-01-26 23:16 ` Stephane Eranian
2017-01-27 13:07 ` Peter Zijlstra
2017-01-27 15:43 ` Arnaldo Carvalho de Melo
2017-01-27 17:35 ` Stephane Eranian
2017-01-27 17:38 ` [PATCH] handle munmap records in tools/perf was: " Arnaldo Carvalho de Melo
2017-01-27 17:46 ` Stephane Eranian
2017-01-27 18:05 ` Arnaldo Carvalho de Melo
2017-01-27 18:10 ` Stephane Eranian
2017-01-27 19:18 ` Arnaldo Carvalho de Melo
2017-01-27 19:26 ` Stephane Eranian
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