linux-kernel - [tip: sched/urgent] workqueue: Use cpu_possible_mask instead of cpu_active

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <161133729644.414.3800664867137502999.tip-bot2@tip-bot2>
Date:   Fri, 22 Jan 2021 17:41:36 -0000
From:   "tip-bot2 for Lai Jiangshan" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Tejun Heo <tj@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/urgent] workqueue: Use cpu_possible_mask instead of
 cpu_active_mask to break affinity

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     547a77d02f8cfb345631ce23b5b548d27afa0fc4
Gitweb:        https://git.kernel.org/tip/547a77d02f8cfb345631ce23b5b548d27afa0fc4
Author:        Lai Jiangshan <laijs@...ux.alibaba.com>
AuthorDate:    Mon, 11 Jan 2021 23:26:33 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 22 Jan 2021 15:09:41 +01:00

workqueue: Use cpu_possible_mask instead of cpu_active_mask to break affinity

The scheduler won't break affinity for us any more, and we should
"emulate" the same behavior when the scheduler breaks affinity for
us.  The behavior is "changing the cpumask to cpu_possible_mask".

And there might be some other CPUs online later while the worker is
still running with the pending work items.  The worker should be allowed
to use the later online CPUs as before and process the work items ASAP.
If we use cpu_active_mask here, we can't achieve this goal but
using cpu_possible_mask can.

Fixes: 06249738a41a ("workqueue: Manually break affinity on hotplug")
Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@....com>
Acked-by: Tejun Heo <tj@...nel.org>
Tested-by: Paul E. McKenney <paulmck@...nel.org>
Tested-by: Valentin Schneider <valentin.schneider@....com>
Link: https://lkml.kernel.org/r/20210111152638.2417-4-jiangshanlai@gmail.com
---
 kernel/workqueue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 9880b6c..1646331 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4920,7 +4920,7 @@ static void unbind_workers(int cpu)
 		raw_spin_unlock_irq(&pool->lock);
 
 		for_each_pool_worker(worker, pool)
-			WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_active_mask) < 0);
+			WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
 
 		mutex_unlock(&wq_pool_attach_mutex);