From: Igor Druzhinin <igor.druzhinin@citrix.com>
To: Juergen Gross <jgross@suse.com>, <xen-devel@lists.xenproject.org>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
"Julien Grall" <julien@xen.org>, "Wei Liu" <wl@xen.org>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"George Dunlap" <George.Dunlap@eu.citrix.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Ian Jackson" <ian.jackson@eu.citrix.com>,
"Jan Beulich" <jbeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH] xen: make sure stop_machine_run() is always called in a tasklet
Date: Fri, 14 Feb 2020 14:06:58 +0000 [thread overview]
Message-ID: <40df666d-246a-656a-94e5-00a85b9280fc@citrix.com> (raw)
In-Reply-To: <20200211093527.6811-1-jgross@suse.com>
On 11/02/2020 09:35, Juergen Gross wrote:
> With core scheduling active it is mandatory for stop_machine_run() to
> be called in a tasklet only, as otherwise a scheduling deadlock would
> occur: stop_machine_run() does a cpu rendezvous by activating a tasklet
> on all other cpus. In case stop_machine_run() was not called in an idle
> vcpu it would block scheduling the idle vcpu on its siblings with core
> scheduling being active, resulting in a hang.
I suppose rcu_barrier() is fine due to process_pending_softirqs() being
called inside? I'm a little concerned by imposing is_vcpu_idle() restriction
in that case as rcu_barrier() could be technically called from a non-tasklet
context.
Igor
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next prev parent reply other threads:[~2020-02-14 14:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 9:35 [Xen-devel] [PATCH] xen: make sure stop_machine_run() is always called in a tasklet Juergen Gross
2020-02-13 9:01 ` Julien Grall
2020-02-13 10:01 ` Jürgen Groß
2020-02-13 10:09 ` Julien Grall
2020-02-14 14:06 ` Igor Druzhinin [this message]
2020-02-14 16:39 ` Jürgen Groß
2020-02-14 17:34 ` Igor Druzhinin
2020-02-15 7:06 ` Jürgen Groß
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