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@xxxxxxxxxxxxx> > > AuthorDate: Thu, 05 Mar 2020 13:38:51 +01:00 > > Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > 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
