linux-kernel - Re: [RFC] Make need_resched() return true when rcu_urgent

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Message-ID: <1532333339.14652.12.camel@infradead.org>
Date:   Mon, 23 Jul 2018 10:08:59 +0200
From:   David Woodhouse <dwmw2@...radead.org>
To:     paulmck@...ux.vnet.ibm.com
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        Peter Zijlstra <peterz@...radead.org>, mhillenb@...zon.de,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>
Subject: Re: [RFC] Make need_resched() return true when rcu_urgent_qs
 requested

On Thu, 2018-07-19 at 10:09 -0700, Paul E. McKenney wrote:
> 
> Of course, the real reason for the lack of fault on your part will not
> because I believe I found the bug elsewhere, but instead because I will
> be dropping your patch (and mine as well) on Frederic's advice.  ;-)

You're keeping the need_resched() one though?

And we are still left with the fact that CONTEXT_TRACKING_FORCE is
making the existing code in guest_enter_irqoff() do the wrong thing for
!NO_HZ_FULL. But in fact the rcu_virt_note_context_switch() there is
completely redundant now we fixed need_resched(), so can be dropped,
leaving only the rcu_user_enter/exit calls for the NO_HZ_FULL case?
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