v4.19.13 snapshot.
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
new file mode 100644
index 0000000..ca8ac28
--- /dev/null
+++ b/kernel/delayacct.c
@@ -0,0 +1,171 @@
+/* delayacct.c - per-task delay accounting
+ *
+ * Copyright (C) Shailabh Nagar, IBM Corp. 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ */
+
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/sched/cputime.h>
+#include <linux/slab.h>
+#include <linux/taskstats.h>
+#include <linux/time.h>
+#include <linux/sysctl.h>
+#include <linux/delayacct.h>
+#include <linux/module.h>
+
+int delayacct_on __read_mostly = 1; /* Delay accounting turned on/off */
+EXPORT_SYMBOL_GPL(delayacct_on);
+struct kmem_cache *delayacct_cache;
+
+static int __init delayacct_setup_disable(char *str)
+{
+ delayacct_on = 0;
+ return 1;
+}
+__setup("nodelayacct", delayacct_setup_disable);
+
+void delayacct_init(void)
+{
+ delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);
+ delayacct_tsk_init(&init_task);
+}
+
+void __delayacct_tsk_init(struct task_struct *tsk)
+{
+ tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);
+ if (tsk->delays)
+ raw_spin_lock_init(&tsk->delays->lock);
+}
+
+/*
+ * Finish delay accounting for a statistic using its timestamps (@start),
+ * accumalator (@total) and @count
+ */
+static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total,
+ u32 *count)
+{
+ s64 ns = ktime_get_ns() - *start;
+ unsigned long flags;
+
+ if (ns > 0) {
+ raw_spin_lock_irqsave(lock, flags);
+ *total += ns;
+ (*count)++;
+ raw_spin_unlock_irqrestore(lock, flags);
+ }
+}
+
+void __delayacct_blkio_start(void)
+{
+ current->delays->blkio_start = ktime_get_ns();
+}
+
+/*
+ * We cannot rely on the `current` macro, as we haven't yet switched back to
+ * the process being woken.
+ */
+void __delayacct_blkio_end(struct task_struct *p)
+{
+ struct task_delay_info *delays = p->delays;
+ u64 *total;
+ u32 *count;
+
+ if (p->delays->flags & DELAYACCT_PF_SWAPIN) {
+ total = &delays->swapin_delay;
+ count = &delays->swapin_count;
+ } else {
+ total = &delays->blkio_delay;
+ count = &delays->blkio_count;
+ }
+
+ delayacct_end(&delays->lock, &delays->blkio_start, total, count);
+}
+
+int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
+{
+ u64 utime, stime, stimescaled, utimescaled;
+ unsigned long long t2, t3;
+ unsigned long flags, t1;
+ s64 tmp;
+
+ task_cputime(tsk, &utime, &stime);
+ tmp = (s64)d->cpu_run_real_total;
+ tmp += utime + stime;
+ d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
+
+ task_cputime_scaled(tsk, &utimescaled, &stimescaled);
+ tmp = (s64)d->cpu_scaled_run_real_total;
+ tmp += utimescaled + stimescaled;
+ d->cpu_scaled_run_real_total =
+ (tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp;
+
+ /*
+ * No locking available for sched_info (and too expensive to add one)
+ * Mitigate by taking snapshot of values
+ */
+ t1 = tsk->sched_info.pcount;
+ t2 = tsk->sched_info.run_delay;
+ t3 = tsk->se.sum_exec_runtime;
+
+ d->cpu_count += t1;
+
+ tmp = (s64)d->cpu_delay_total + t2;
+ d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
+
+ tmp = (s64)d->cpu_run_virtual_total + t3;
+ d->cpu_run_virtual_total =
+ (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
+
+ /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
+
+ raw_spin_lock_irqsave(&tsk->delays->lock, flags);
+ tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
+ d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
+ tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
+ d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
+ tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
+ d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
+ d->blkio_count += tsk->delays->blkio_count;
+ d->swapin_count += tsk->delays->swapin_count;
+ d->freepages_count += tsk->delays->freepages_count;
+ raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
+
+ return 0;
+}
+
+__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
+{
+ __u64 ret;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&tsk->delays->lock, flags);
+ ret = nsec_to_clock_t(tsk->delays->blkio_delay +
+ tsk->delays->swapin_delay);
+ raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
+ return ret;
+}
+
+void __delayacct_freepages_start(void)
+{
+ current->delays->freepages_start = ktime_get_ns();
+}
+
+void __delayacct_freepages_end(void)
+{
+ delayacct_end(
+ ¤t->delays->lock,
+ ¤t->delays->freepages_start,
+ ¤t->delays->freepages_delay,
+ ¤t->delays->freepages_count);
+}
+