From: Greg KH <gregkh@linuxfoundation.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: "stable@vger.kernel.org" <stable@vger.kernel.org>,
linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
x86 <x86@kernel.org>
Subject: Re: [tip: perf/core] perf/core: Fix endless multiplex timer
Date: Thu, 6 Aug 2020 20:53:53 +0200 [thread overview]
Message-ID: <20200806185353.GA2942033@kroah.com> (raw)
In-Reply-To: <abd1dde6-2761-ae91-195c-cd7c4e4515c6@arm.com>
On Thu, Aug 06, 2020 at 07:11:24PM +0100, Robin Murphy wrote:
> On 2020-03-20 12:58, tip-bot2 for Peter Zijlstra wrote:
> > The following commit has been merged into the perf/core branch of tip:
> >
> > Commit-ID: 90c91dfb86d0ff545bd329d3ddd72c147e2ae198
> > Gitweb: https://git.kernel.org/tip/90c91dfb86d0ff545bd329d3ddd72c147e2ae198
> > Author: Peter Zijlstra <peterz@infradead.org>
> > AuthorDate: Thu, 05 Mar 2020 13:38:51 +01:00
> > Committer: Peter Zijlstra <peterz@infradead.org>
> > CommitterDate: Fri, 20 Mar 2020 13:06:22 +01:00
> >
> > perf/core: Fix endless multiplex timer
> >
> > Kan and Andi reported that we fail to kill rotation when the flexible
> > events go empty, but the context does not. XXX moar
> >
> > Fixes: fd7d55172d1e ("perf/cgroups: Don't rotate events for cgroups unnecessarily")
>
> Can this patch (commit 90c91dfb86d0 ("perf/core: Fix endless multiplex
> timer") upstream) be applied to stable please? For PMU drivers built as
> modules, the bug can actually kill the system, since the runaway hrtimer
> loop keeps calling pmu->{enable,disable} after all the events have been
> closed and dropped their references to pmu->module. Thus legitimately
> unloading the module once things have got into this state quickly results in
> a crash when those callbacks disappear.
>
> (FWIW I spent about two days fighting with this while testing a new driver
> as a module against the 5.3 kernel installed on someone else's machine,
> assuming it was a bug in my code...)
What exactly kernel(s) do you wish for it to be applied to? It's
already in the latest stable releases of 5.7.y.
thanks,
greg k-h
next prev parent reply other threads:[~2020-08-06 18:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 20:28 [PATCH] perf/core: Fix endless multiplex timer kan.liang
2020-03-03 21:08 ` Peter Zijlstra
2020-03-04 1:40 ` Liang, Kan
2020-03-04 9:33 ` Peter Zijlstra
2020-03-04 14:20 ` Liang, Kan
2020-03-05 12:38 ` Peter Zijlstra
2020-03-05 17:56 ` Liang, Kan
2020-03-20 12:58 ` [tip: perf/core] " tip-bot2 for Peter Zijlstra
2020-08-06 18:11 ` Robin Murphy
2020-08-06 18:53 ` Greg KH [this message]
2020-08-06 20:40 ` Robin Murphy
2020-03-24 6:00 ` [perf/core] 92b1f046a2: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2020-03-24 12:52 ` Liang, Kan
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