On 01/22/2014 12:14 PM, Peter Zijlstra wrote:
On Tue, Jan 21, 2014 at 05:28:37PM -0500, Sasha Levin wrote:[ 0.000000] Initmem setup node 30 [mem 0x12ee000000-0x138dffffff] [ 0.000000] NODE_DATA [mem 0xcfa42000-0xcfa72fff] [ 0.000000] NODE_DATA(30) on node 1 [ 0.000000] Initmem setup node 31 [mem 0x138e000000-0x142fffffff] [ 0.000000] NODE_DATA [mem 0xcfa11000-0xcfa41fff] [ 0.000000] NODE_DATA(31) on node 1 [ 0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00 [ 0.000000] kvm-clock: cpu 0, msr 0:cf991001, boot clock [133538.294040] Zone ranges: [133538.294338] DMA [mem 0x00001000-0x00ffffff] [133538.294804] DMA32 [mem 0x01000000-0xffffffff] [133538.295223] Normal [mem 0x100000000-0x142fffffff] [133538.295670] Movable zone start for each nodeOK, took me a while to fiddle with KVM and all the various muck around that to reproduce. But I can confirm the below does fix the issue for me. I'm hoping to not have to re-introcude the kevents_up() check, but I need to figure out what hardware triggered that and test again. --- Subject: sched/clock: Fixup early sched_clock initialization From: Peter Zijlstra <[email protected]> Date: Wed, 22 Jan 2014 12:59:18 +0100 The code would assume sched_clock_stable() and switch to !stable later, this switch brings a discontinuity in time. The discontinuity on switching from stable to unstable was always present, but previously we would set stable/unstable before initializing TSC and usually stick to the one we start out with. So the static_key bits brought an extra switch where there previously wasn't one. Things are further complicated by the fact that we cannot use static_key as early as we usually call set_sched_clock_stable(). Fix things by tracking the stable state in a regular variable and only set the static_key to the right state on sched_clock_init(), which is ran right after late_time_init->tsc_init(). Before this we would not be using the TSC anyway. Fixes: 35af99e646c7 ("sched/clock, x86: Use a static_key for sched_clock_stable") Cc: [email protected] Cc: Mike Galbraith <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Thomas Gleixner <[email protected]> Cc: John Stultz <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Eliezer Tamir <[email protected]> Cc: [email protected] Reported-by: Sasha Levin <[email protected]> Reported-by: [email protected] Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/[email protected]
The patch fixes the problem for me. Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
