6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Costa Shulyupin <costa.shul@xxxxxxxxxx> [ Upstream commit 56c2cb10120894be40c40a9bf0ce798da14c50f6 ] During CPU-down hotplug, hrtimers may migrate to isolated CPUs, compromising CPU isolation. Address this issue by masking valid CPUs for hrtimers using housekeeping_cpumask(HK_TYPE_TIMER). Suggested-by: Waiman Long <longman@xxxxxxxxxx> Signed-off-by: Costa Shulyupin <costa.shul@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: Waiman Long <longman@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240222200856.569036-1-costa.shul@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- kernel/time/hrtimer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 9bb88836c42e6..314fb7598a879 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -38,6 +38,7 @@ #include <linux/sched/deadline.h> #include <linux/sched/nohz.h> #include <linux/sched/debug.h> +#include <linux/sched/isolation.h> #include <linux/timer.h> #include <linux/freezer.h> #include <linux/compat.h> @@ -2220,8 +2221,8 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base, int hrtimers_cpu_dying(unsigned int dying_cpu) { + int i, ncpu = cpumask_any_and(cpu_active_mask, housekeeping_cpumask(HK_TYPE_TIMER)); struct hrtimer_cpu_base *old_base, *new_base; - int i, ncpu = cpumask_first(cpu_active_mask); tick_cancel_sched_timer(dying_cpu); -- 2.43.0
