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Date: Thu, 7 Mar 2019 16:26:39 -0300 From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com> To: Stephane Eranian <eranian@...gle.com> Cc: Peter Zijlstra <peterz@...radead.org>, Arnaldo Carvalho de Melo <acme@...hat.com>, Andi Kleen <ak@...ux.intel.com>, Kan Liang <kan.liang@...el.com>, Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...nel.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCH] perf/core: restore mmap record type correctly Em Thu, Mar 07, 2019 at 08:09:39PM +0100, Peter Zijlstra escreveu: > On Thu, Mar 07, 2019 at 04:03:30PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Thu, Mar 07, 2019 at 10:52:33AM -0800, Stephane Eranian escreveu: > > > On mmap(), perf_events generates a RECORD_MMAP record and then checks > > > which events are interested in this record. There are currently 2 versions > > > of mmap records: RECORD_MMAP and RECORD_MMAP2. MMAP2 is larger. The event > > > configuration controls which version the user level tool accepts. If the > > > event->attr.mmap2=1 field then MMAP2 record is returned. The > > > perf_event_mmap_output() takes care of this. It checks attr->mmap2 and corrects > > > the record fields before putting it in the sampling buffer of the event. > > > At the end the function restores the modified MMAP record fields. > > > The problem is that the function restores the size but not the > > > type. Thus, if a subsequent event only accepts MMAP type, then it would > > > instead receive an MMAP2 record with a size of MMAP record. > > > This patch fixes the problem by restoring the record type on exit. > > Right, simple enough, bug fixed, Peter, I'm taking this one, ok? > Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org> BTW, added: Fixes: 13d7a2410fa6 ("perf: Add attr->mmap2 attribute to an event") For the stable guys to pick this up. Please try to add the fixes tag in the future. Thanks, - Arnaldo
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