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Message-Id: <20240203154334.791910-5-longman@redhat.com>
Date: Sat, 3 Feb 2024 10:43:33 -0500
From: Waiman Long <longman@...hat.com>
To: Tejun Heo <tj@...nel.org>,
Lai Jiangshan <jiangshanlai@...il.com>
Cc: linux-kernel@...r.kernel.org,
Juri Lelli <juri.lelli@...hat.com>,
Cestmir Kalina <ckalina@...hat.com>,
Alex Gladkov <agladkov@...hat.com>,
Phil Auld <pauld@...hat.com>,
Costa Shulyupin <cshulyup@...hat.com>,
Waiman Long <longman@...hat.com>
Subject: [PATCH-wq v2 4/5] kernel/workqueue: Let rescuers follow unbound wq cpumask changes
From: Juri Lelli <juri.lelli@...hat.com>
When workqueue cpumask changes are committed the associated rescuer (if
one exists) affinity is not touched and this might be a problem down the
line for isolated setups.
Make sure rescuers affinity is updated every time a workqueue cpumask
changes, so that rescuers can't break isolation.
[longman: set_cpus_allowed_ptr() will block until the designated task
is enqueued on an allowed CPU, no wake_up_process() needed. Also use
the unbound_effective_cpumask() helper as suggested by Tejun.]
Signed-off-by: Juri Lelli <juri.lelli@...hat.com>
Signed-off-by: Waiman Long <longman@...hat.com>
---
kernel/workqueue.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index ee934c2c6ea8..172f7299aa71 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4905,6 +4905,11 @@ static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
/* update node_nr_active->max */
wq_update_node_max_active(ctx->wq, -1);
+ /* rescuer needs to respect wq cpumask changes */
+ if (ctx->wq->rescuer)
+ set_cpus_allowed_ptr(ctx->wq->rescuer->task,
+ unbound_effective_cpumask(ctx->wq));
+
mutex_unlock(&ctx->wq->mutex);
}
--
2.39.3
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