From 98744b408c757901df57fa50cbd5826245dc3a1f Mon Sep 17 00:00:00 2001 From: Daniel Lezcano Date: Mon, 29 Aug 2016 08:44:03 +0200 Subject: clocksource/drivers/atmel-pit: Fix compilation error MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The previous fix introduced a check against the ret variable which is not defined, hence producing a compilation error: linux/drivers/clocksource/timer-atmel-pit.c: In function ‘at91sam926x_pit_dt_init’: linux/drivers/clocksource/timer-atmel-pit.c:264:2: error: ‘ret’ undeclared (first use in this function) ret = clk_prepare_enable(data->mck); ^ linux/drivers/clocksource/timer-atmel-pit.c:264:2: note: each undeclared identifier is reported only once for each function it appears in Add the missing the variable 'ret'. Fixes: 504f34c9e45c "clocksource/drivers/atmel-pit: Convert init function to return error" Signed-off-by: Daniel Lezcano Cc: alexandre.belloni@free-electrons.com Cc: motobud@gmail.com Cc: realbright@lgcns.com Link: http://lkml.kernel.org/r/1472453043-24287-1-git-send-email-daniel.lezcano@linaro.org Signed-off-by: Thomas Gleixner diff --git a/drivers/clocksource/timer-atmel-pit.c b/drivers/clocksource/timer-atmel-pit.c index 3494bc5..7f0f5b2 100644 --- a/drivers/clocksource/timer-atmel-pit.c +++ b/drivers/clocksource/timer-atmel-pit.c @@ -240,6 +240,7 @@ static int __init at91sam926x_pit_common_init(struct pit_data *data) static int __init at91sam926x_pit_dt_init(struct device_node *node) { struct pit_data *data; + int ret; data = kzalloc(sizeof(*data), GFP_KERNEL); if (!data) -- cgit v0.10.2 From 08d072599234c959b0b82b63fa252c129225a899 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Fri, 2 Sep 2016 14:38:23 +0800 Subject: tick/nohz: Fix softlockup on scheduler stalls in kvm guest MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit tick_nohz_start_idle() is prevented to be called if the idle tick can't be stopped since commit 1f3b0f8243cb934 ("tick/nohz: Optimize nohz idle enter"). As a result, after suspend/resume the host machine, full dynticks kvm guest will softlockup: NMI watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [swapper/0:0] Call Trace: default_idle+0x31/0x1a0 arch_cpu_idle+0xf/0x20 default_idle_call+0x2a/0x50 cpu_startup_entry+0x39b/0x4d0 rest_init+0x138/0x140 ? rest_init+0x5/0x140 start_kernel+0x4c1/0x4ce ? set_init_arg+0x55/0x55 ? early_idt_handler_array+0x120/0x120 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0x142/0x14f In addition, cat /proc/stat | grep cpu in guest or host: cpu 398 16 5049 15754 5490 0 1 46 0 0 cpu0 206 5 450 0 0 0 1 14 0 0 cpu1 81 0 3937 3149 1514 0 0 9 0 0 cpu2 45 6 332 6052 2243 0 0 11 0 0 cpu3 65 2 328 6552 1732 0 0 11 0 0 The idle and iowait states are weird 0 for cpu0(housekeeping). The bug is present in both guest and host kernels, and they both have cpu0's idle and iowait states issue, however, host kernel's suspend/resume path etc will touch watchdog to avoid the softlockup. - The watchdog will not be touched in tick_nohz_stop_idle path (need be touched since the scheduler stall is expected) if idle_active flags are not detected. - The idle and iowait states will not be accounted when exit idle loop (resched or interrupt) if idle start time and idle_active flags are not set. This patch fixes it by reverting commit 1f3b0f8243cb934 since can't stop idle tick doesn't mean can't be idle. Fixes: 1f3b0f8243cb934 ("tick/nohz: Optimize nohz idle enter") Signed-off-by: Wanpeng Li Cc: Sanjeev Yadav Cc: Gaurav Jindal Cc: stable@vger.kernel.org Cc: kvm@vger.kernel.org Cc: Radim Krčmář Cc: Peter Zijlstra Cc: Paolo Bonzini Link: http://lkml.kernel.org/r/1472798303-4154-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Thomas Gleixner diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 204fdc8..2ec7c00 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -908,10 +908,11 @@ static void __tick_nohz_idle_enter(struct tick_sched *ts) ktime_t now, expires; int cpu = smp_processor_id(); + now = tick_nohz_start_idle(ts); + if (can_stop_idle_tick(cpu, ts)) { int was_stopped = ts->tick_stopped; - now = tick_nohz_start_idle(ts); ts->idle_calls++; expires = tick_nohz_stop_sched_tick(ts, now, cpu); -- cgit v0.10.2