| Message ID | 1402962240-31066-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 3c29703..9873816 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -232,6 +232,11 @@ again: goto again; } timer->base = new_base; + } else { + if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) { + cpu = this_cpu; + goto again; + } } return new_base; }
This is a note to let you know that I have just added a patch titled hrtimer: Prevent remote enqueue of leftmost timers to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.24. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 53379610618dcaceac13c14443a93c97466f5488 Mon Sep 17 00:00:00 2001 From: Leon Ma <xindong.ma@intel.com> Date: Wed, 30 Apr 2014 16:43:10 +0800 Subject: hrtimer: Prevent remote enqueue of leftmost timers commit 012a45e3f4af68e86d85cce060c6c2fed56498b2 upstream. If a cpu is idle and starts an hrtimer which is not pinned on that same cpu, the nohz code might target the timer to a different cpu. In the case that we switch the cpu base of the timer we already have a sanity check in place, which determines whether the timer is earlier than the current leftmost timer on the target cpu. In that case we enqueue the timer on the current cpu because we cannot reprogram the clock event device on the target. If the timers base is already the target CPU we do not have this sanity check in place so we enqueue the timer as the leftmost timer in the target cpus rb tree, but we cannot reprogram the clock event device on the target cpu. So the timer expires late and subsequently prevents the reprogramming of the target cpu clock event device until the previously programmed event fires or a timer with an earlier expiry time gets enqueued on the target cpu itself. Add the same target check as we have for the switch base case and start the timer on the current cpu if it would become the leftmost timer on the target. [ tglx: Rewrote subject and changelog ] Signed-off-by: Leon Ma <xindong.ma@intel.com> Link: http://lkml.kernel.org/r/1398847391-5994-1-git-send-email-xindong.ma@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- kernel/hrtimer.c | 5 +++++ 1 file changed, 5 insertions(+) -- 1.9.1