This is a note to let you know that I've just added the patch titled timers, sched_clock: Update timeout for clock wrap to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: timers-sched_clock-update-timeout-for-clock-wrap.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sun Mar 18 16:55:33 CET 2018 From: David Engraf <david.engraf@xxxxxxxxx> Date: Fri, 17 Feb 2017 08:51:03 +0100 Subject: timers, sched_clock: Update timeout for clock wrap From: David Engraf <david.engraf@xxxxxxxxx> [ Upstream commit 1b8955bc5ac575009835e371ae55e7f3af2197a9 ] The scheduler clock framework may not use the correct timeout for the clock wrap. This happens when a new clock driver calls sched_clock_register() after the kernel called sched_clock_postinit(). In this case the clock wrap timeout is too long thus sched_clock_poll() is called too late and the clock already wrapped. On my ARM system the scheduler was no longer scheduling any other task than the idle task because the sched_clock() wrapped. Signed-off-by: David Engraf <david.engraf@xxxxxxxxx> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/time/sched_clock.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -205,6 +205,11 @@ sched_clock_register(u64 (*read)(void), update_clock_read_data(&rd); + if (sched_clock_timer.function != NULL) { + /* update timeout for clock wrap */ + hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + } + r = rate; if (r >= 4000000) { r /= 1000000; Patches currently in stable-queue which might be from david.engraf@xxxxxxxxx are queue-4.9/timers-sched_clock-update-timeout-for-clock-wrap.patch