Messages in this thread | | | Subject | Re: [tip: perf/core] perf/core: Fix endless multiplex timer | From | Robin Murphy <> | Date | Thu, 6 Aug 2020 21:40:17 +0100 |
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On 2020-08-06 19:53, Greg KH wrote: > 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.
Sorry, I implicitly meant 5.4.y there - the buggy commit was merged in 5.3, the fix in 5.7, so I think that's the only "stable" branch in between that warrants explicit action. Apologies if I'm getting the terminology wrong.
Cheers, Robin.
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