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sched: Change nr_uninterruptible type to unsigned long

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commit 36569780b0d64de283f9d6c2195fd1a43e221ee8 upstream.

The commit e6fe3f422b ("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: e6fe3f422b ("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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Aruna Ramakrishna
2025-07-09 17:33:28 +00:00
committed by Greg Kroah-Hartman
parent f371ad6471
commit 496efa228f
2 changed files with 2 additions and 2 deletions
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2
kernel/sched/loadavg.c
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@@ -80,7 +80,7 @@ long calc_load_fold_active(struct rq *this_rq, long adjust)
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;

2
kernel/sched/sched.h
View File

@@ -1011,7 +1011,7 @@ 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;