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From: "Jürgen Groß" <jgross@suse.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH V2] xen: Enable interrupts when calling _cond_resched()
Date: Wed, 19 Feb 2020 19:42:29 +0100	[thread overview]
Message-ID: <a2dee352-409b-1c6b-e7f0-bcbbf5d71a95@suse.com> (raw)
In-Reply-To: <878skypjrh.fsf@nanos.tec.linutronix.de>

On 19.02.20 18:30, Thomas Gleixner wrote:
> xen_maybe_preempt_hcall() is called from the exception entry point
> xen_do_hypervisor_callback with interrupts disabled.
> 
> _cond_resched() evades the might_sleep() check in cond_resched() which
> would have caught that and schedule_debug() unfortunately lacks a check
> for irqs_disabled().
> 
> Enable interrupts around the call and use cond_resched() to catch future
> issues.
> 
> Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted")
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen


WARNING: multiple messages have this Message-ID (diff)
From: "Jürgen Groß" <jgross@suse.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>
Cc: xen-devel@lists.xenproject.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	x86@kernel.org, Stefano Stabellini <sstabellini@kernel.org>
Subject: Re: [Xen-devel] [PATCH V2] xen: Enable interrupts when calling _cond_resched()
Date: Wed, 19 Feb 2020 19:42:29 +0100	[thread overview]
Message-ID: <a2dee352-409b-1c6b-e7f0-bcbbf5d71a95@suse.com> (raw)
In-Reply-To: <878skypjrh.fsf@nanos.tec.linutronix.de>

On 19.02.20 18:30, Thomas Gleixner wrote:
> xen_maybe_preempt_hcall() is called from the exception entry point
> xen_do_hypervisor_callback with interrupts disabled.
> 
> _cond_resched() evades the might_sleep() check in cond_resched() which
> would have caught that and schedule_debug() unfortunately lacks a check
> for irqs_disabled().
> 
> Enable interrupts around the call and use cond_resched() to catch future
> issues.
> 
> Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted")
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen


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  reply	other threads:[~2020-02-19 18:42 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19 11:01 [PATCH] xen: Enable interrupts when calling _cond_resched() Thomas Gleixner
2020-02-19 11:01 ` [Xen-devel] " Thomas Gleixner
2020-02-19 12:02 ` Jürgen Groß
2020-02-19 12:02   ` [Xen-devel] " Jürgen Groß
2020-02-19 14:53   ` Thomas Gleixner
2020-02-19 14:53     ` [Xen-devel] " Thomas Gleixner
2020-02-19 17:30     ` [PATCH V2] " Thomas Gleixner
2020-02-19 17:30       ` [Xen-devel] " Thomas Gleixner
2020-02-19 18:42       ` Jürgen Groß [this message]
2020-02-19 18:42         ` Jürgen Groß

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