LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Vince Weaver <vincent.weaver@maine.edu>
To: linux-kernel@vger.kernel.org
Cc: Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Stephane Eranian <eranian@gmail.com>
Subject: perf: bug in rdpmc/mmap accounting after exec
Date: Wed, 26 Jul 2017 15:39:01 -0400 (EDT)
Message-ID: <alpine.DEB.2.20.1707261530320.3810@macbook-air> (raw)

Hello

so one last bug found by the PAPI testsuite.

This one involves the rdpmc auto-disable on last unmap of an event 
feature.

Failing test case:

	fd=perf_event_open();
	addr=mmap(fd);
	exec()  // without closing or unmapping the event
	fd=perf_event_open();
	addr=mmap(fd);
	rdpmc()	// GPFs due to rdpmc being disabled

I won't pretend to be able to follow the rdpmc disabling code, but if I 
add some printks it looks like 
	current->mm->context.perf_rdpmc_allowed
isn't properly being reset on exec?

In fact, current->mm->context.perf_rdpmc_allowed goes negative which seems
like it shouldn't happen?

Anyway, a test case for this can be found in the perf_event_tests,
	tests/rdpmc/rdpmc_exec_papi

Vince

             reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-26 19:39 Vince Weaver [this message]
2017-08-02 17:39 ` Peter Zijlstra
2017-08-03 18:04   ` Vince Weaver
2017-08-04  0:37   ` Andy Lutomirski
2017-08-04  9:17     ` Peter Zijlstra
2017-08-04 11:12       ` Peter Zijlstra
2017-08-10 12:01   ` [tip:perf/core] perf/x86: Fix RDPMC vs. mm_struct tracking tip-bot for Peter Zijlstra

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=alpine.DEB.2.20.1707261530320.3810@macbook-air \
    --to=vincent.weaver@maine.edu \
    --cc=acme@kernel.org \
    --cc=eranian@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git