Re: [PATCH 1/1] perf,tools: add time out to force stop endless mmap processing

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: "Liang, Kan" <kan.liang@intel.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Huang, Ying" <ying.huang@intel.com>,
	"andi@firstfloor.org" <andi@firstfloor.org>
Subject: Re: [PATCH 1/1] perf,tools: add time out to force stop endless mmap processing
Date: Thu, 11 Jun 2015 12:37:30 -0300	[thread overview]
Message-ID: <20150611153730.GA3195@kernel.org> (raw)
In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F07701875D03@SHSMSX103.ccr.corp.intel.com>

Em Thu, Jun 11, 2015 at 02:27:40PM +0000, Liang, Kan escreveu:
> > Em Wed, Jun 10, 2015 at 03:46:04AM -0400, kan.liang@intel.com escreveu:
> > > perf top reads all threads' /proc/xxx/maps. If there is any threads
> > > which generating a keeping growing huge /proc/xxx/maps, perf will do
> > > infinite loop in perf_event__synthesize_mmap_events.
> > > This patch fixes this issue by adding a time out to force stop this
> > > kind of endless mmap processing.
> > >
> > > Reported-by: Huang, Ying <ying.huang@intel.com>
> > > Signed-off-by: Kan Liang <kan.liang@intel.com>
> > 
> > So we will silently stop processing those events?
> > 
> > We will make progress, no doubt, but I think the user needs to be warned
> > about this situation, so that later on when/if samples for those maps
> > appear and don't get resolved at least we will know that this is the reason.

> I will add warning message for this kind of time out.

Thanks!

- Arnaldo