linux-kernel - [patch v7 07/10] task isolation: enable return to userspace processing

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Date:   Fri, 12 Nov 2021 09:35:38 -0300
From:   Marcelo Tosatti <mtosatti@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Nitesh Lal <nilal@...hat.com>,
        Nicolas Saenz Julienne <nsaenzju@...hat.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Alex Belits <abelits@...its.com>, Peter Xu <peterx@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>
Subject: [patch v7 07/10] task isolation: enable return to userspace processing

Enable processing of pending task isolation work if per-CPU vmstats
are out of sync with global vmstats.

Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>

---
 include/linux/task_isolation.h |   22 +++++++++++++++++++++-
 kernel/task_isolation.c        |   13 +++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

Index: linux-2.6/include/linux/task_isolation.h
===================================================================
--- linux-2.6.orig/include/linux/task_isolation.h
+++ linux-2.6/include/linux/task_isolation.h
@@ -5,6 +5,9 @@
 
 #ifdef CONFIG_CPU_ISOLATION
 
+#include <linux/vmstat.h>
+#include <uapi/linux/prctl.h>
+
 struct isol_info {
 	/* Which features have been configured */
 	u64 conf_mask;
@@ -51,7 +54,24 @@ void isolation_exit_to_user_mode(void);
 
 static inline int task_isol_has_work(void)
 {
-	return 0;
+	int cpu, ret;
+	struct isol_info *i;
+
+	if (likely(current->isol_info == NULL))
+		return 0;
+
+	i = current->isol_info;
+	if (i->active_mask != ISOL_F_QUIESCE)
+		return 0;
+
+	if (!(i->quiesce_mask & ISOL_F_QUIESCE_VMSTATS))
+		return 0;
+
+	cpu = get_cpu();
+	ret = per_cpu(vmstat_dirty, cpu);
+	put_cpu();
+
+	return ret;
 }
 
 #else
Index: linux-2.6/kernel/task_isolation.c
===================================================================
--- linux-2.6.orig/kernel/task_isolation.c
+++ linux-2.6/kernel/task_isolation.c
@@ -23,6 +23,13 @@
 
 void __tsk_isol_exit(struct task_struct *tsk)
 {
+	struct isol_info *i;
+
+	i = tsk->isol_info;
+	if (!i)
+		return;
+
+	static_key_slow_dec(&vmstat_sync_enabled);
 }
 
 void __tsk_isol_free(struct task_struct *tsk)
@@ -41,6 +48,12 @@ static struct isol_info *tsk_isol_alloc_
 	if (unlikely(!info))
 		return ERR_PTR(-ENOMEM);
 
+	preempt_disable();
+	init_sync_vmstat();
+	preempt_enable();
+
+	static_key_slow_inc(&vmstat_sync_enabled);
+
 	return info;
 }