Arnaldo Carvalho de Melo [a...@kernel.org] wrote: | Em Thu, Jun 11, 2015 at 11:00:04PM -0700, Sukadev Bhattiprolu escreveu: | > >From 6669ed960a3ee4f9a02790f60b6a73ffc82fd6de Mon Sep 17 00:00:00 2001 | > From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> | > Date: Fri, 12 Jun 2015 01:28:36 -0400 | > Subject: [PATCH] perf, tools: Fix crash in perf trace | > | > I get following crash on multiple systems and across several releases | > (at least since v3.18). | | Trying it in perf/core I get: |
Ah, I should have based on perf/core. | util/evlist.c: In function ‘perf_evlist__mmap_read’: | util/evlist.c:645:6: error: wrong type argument to unary exclamation | mark | if (!md->refcnt) | | Trying after changing it to !atomic_read(&md->refcnt) | | And it fixes the segfault that I reproduced, but this still looks | strange, i.e. if it hit zero, then it should not have been used at this | point anymore... Will look at it again in the weekend. :-\ I think its a small window - where application has started exiting, and set the PERF_EVENT_STATE_EXIT flag, but has not exited "enough" to issue a SIGCHLD. (Also we check the 'done' flag once - we could get SIGCHLD just after the check?) Anyway, the poll() in this window returns with POLLHUP and we unmap the region. Sukadev -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
