This is a note to let you know that I've just added the patch titled
timers: Reinitialize per cpu bases on hotplug
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-reinitialize-per-cpu-bases-on-hotplug.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 26456f87aca7157c057de65c9414b37f1ab881d1 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Wed, 27 Dec 2017 21:37:25 +0100
Subject: timers: Reinitialize per cpu bases on hotplug
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 26456f87aca7157c057de65c9414b37f1ab881d1 upstream.
The timer wheel bases are not (re)initialized on CPU hotplug. That leaves
them with a potentially stale clk and next_expiry valuem, which can cause
trouble then the CPU is plugged.
Add a prepare callback which forwards the clock, sets next_expiry to far in
the future and reset the control flags to a known state.
Set base->must_forward_clk so the first timer which is queued will try to
forward the clock to current jiffies.
Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel")
Reported-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1712272152200.2431@nanos
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/cpuhotplug.h | 2 +-
include/linux/timer.h | 4 +++-
kernel/cpu.c | 4 ++--
kernel/time/timer.c | 15 +++++++++++++++
4 files changed, 21 insertions(+), 4 deletions(-)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -48,7 +48,7 @@ enum cpuhp_state {
CPUHP_ARM_SHMOBILE_SCU_PREPARE,
CPUHP_SH_SH3X_PREPARE,
CPUHP_BLK_MQ_PREPARE,
- CPUHP_TIMERS_DEAD,
+ CPUHP_TIMERS_PREPARE,
CPUHP_NOTF_ERR_INJ_PREPARE,
CPUHP_MIPS_SOC_PREPARE,
CPUHP_BRINGUP_CPU,
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -274,9 +274,11 @@ unsigned long round_jiffies_up(unsigned
unsigned long round_jiffies_up_relative(unsigned long j);
#ifdef CONFIG_HOTPLUG_CPU
+int timers_prepare_cpu(unsigned int cpu);
int timers_dead_cpu(unsigned int cpu);
#else
-#define timers_dead_cpu NULL
+#define timers_prepare_cpu NULL
+#define timers_dead_cpu NULL
#endif
#endif
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1309,9 +1309,9 @@ static struct cpuhp_step cpuhp_bp_states
* before blk_mq_queue_reinit_notify() from notify_dead(),
* otherwise a RCU stall occurs.
*/
- [CPUHP_TIMERS_DEAD] = {
+ [CPUHP_TIMERS_PREPARE] = {
.name = "timers:dead",
- .startup.single = NULL,
+ .startup.single = timers_prepare_cpu,
.teardown.single = timers_dead_cpu,
},
/* Kicks the plugged cpu into life */
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1851,6 +1851,21 @@ static void migrate_timer_list(struct ti
}
}
+int timers_prepare_cpu(unsigned int cpu)
+{
+ struct timer_base *base;
+ int b;
+
+ for (b = 0; b < NR_BASES; b++) {
+ base = per_cpu_ptr(&timer_bases[b], cpu);
+ base->clk = jiffies;
+ base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA;
+ base->is_idle = false;
+ base->must_forward_clk = true;
+ }
+ return 0;
+}
+
int timers_dead_cpu(unsigned int cpu)
{
struct timer_base *old_base;
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-4.9/nohz-prevent-a-timer-interrupt-storm-in-tick_nohz_stop_sched_tick.patch
queue-4.9/timers-invoke-timer_start_debug-where-it-makes-sense.patch
queue-4.9/x86-vm86-32-switch-to-flush_tlb_mm_range-in-mark_screen_rdonly.patch
queue-4.9/x86-mm-add-the-nopcid-boot-option-to-turn-off-pcid.patch
queue-4.9/x86-mm-enable-cr4.pcide-on-supported-systems.patch
queue-4.9/sync-objtool-s-copy-of-x86-opcode-map.txt.patch
queue-4.9/x86-smpboot-remove-stale-tlb-flush-invocations.patch
queue-4.9/timers-use-deferrable-base-independent-of-base-nohz_active.patch
queue-4.9/x86-mm-remove-the-up-asm-tlbflush.h-code-always-use-the-formerly-smp-code.patch
queue-4.9/x86-mm-reimplement-flush_tlb_page-using-flush_tlb_mm_range.patch
queue-4.9/x86-mm-make-flush_tlb_mm_range-more-predictable.patch
queue-4.9/x86-mm-remove-flush_tlb-and-flush_tlb_current_task.patch
queue-4.9/x86-mm-disable-pcid-on-32-bit-kernels.patch
queue-4.9/timers-reinitialize-per-cpu-bases-on-hotplug.patch
queue-4.9/x86-mm-64-fix-reboot-interaction-with-cr4.pcide.patch