5.15-stable review patch. If anyone has any objections, please let me know.
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From: Aruna Ramakrishna aruna.ramakrishna@oracle.com
commit 36569780b0d64de283f9d6c2195fd1a43e221ee8 upstream.
The commit e6fe3f422be1 ("sched: Make multiple runqueue task counters 32-bit") changed nr_uninterruptible to an unsigned int. But the nr_uninterruptible values for each of the CPU runqueues can grow to large numbers, sometimes exceeding INT_MAX. This is valid, if, over time, a large number of tasks are migrated off of one CPU after going into an uninterruptible state. Only the sum of all nr_interruptible values across all CPUs yields the correct result, as explained in a comment in kernel/sched/loadavg.c.
Change the type of nr_uninterruptible back to unsigned long to prevent overflows, and thus the miscalculation of load average.
Fixes: e6fe3f422be1 ("sched: Make multiple runqueue task counters 32-bit")
Signed-off-by: Aruna Ramakrishna aruna.ramakrishna@oracle.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/20250709173328.606794-1-aruna.ramakrishna@oracle.c... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/sched/loadavg.c | 2 +- kernel/sched/sched.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/sched/loadavg.c +++ b/kernel/sched/loadavg.c @@ -81,7 +81,7 @@ long calc_load_fold_active(struct rq *th long nr_active, delta = 0;
nr_active = this_rq->nr_running - adjust; - nr_active += (int)this_rq->nr_uninterruptible; + nr_active += (long)this_rq->nr_uninterruptible;
if (nr_active != this_rq->calc_load_active) { delta = nr_active - this_rq->calc_load_active; --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -971,7 +971,7 @@ struct rq { * one CPU and if it got migrated afterwards it may decrease * it on another CPU. Always updated under the runqueue lock: */ - unsigned int nr_uninterruptible; + unsigned long nr_uninterruptible;
struct task_struct __rcu *curr; struct task_struct *idle;