From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, Andi Kleen <andi@firstfloor.org>,
linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
stable@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] x86/traps: Don't for in_interrupt() to return true in IST handlers
Date: Tue, 24 May 2016 11:51:24 +0200 [thread overview]
Message-ID: <20160524095124.GR3193@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160524093629.GA2388@pd.tnic>
@Andy, its linux-kernel@vger, not lkml@vger :-)
On Tue, May 24, 2016 at 11:36:29AM +0200, Borislav Petkov wrote:
> On Tue, May 24, 2016 at 10:59:45AM +0200, Peter Zijlstra wrote:
> > Which use a sequence of: in_nmi(), in_irq(), in_softirq() to pick 1 out
> > of 4 possible contexts.
>
> So should we make it cleaner and explicit and define a 5th context of
> priorities higher than NMI?
>
> There's some room between those two:
>
> * NMI_MASK: 0x00100000
> * PREEMPT_NEED_RESCHED: 0x80000000
>
A lot of pain; we'd have to go grow a whole bunch of things to 5.
Also, I don't think 5 is enough to model all the IST nesting. I'm also
not sure we really care too much; IST stuff is relatively rare. It just
means we can loose IST based trace events and the like, because its
treated as recursion.
So I think keeping it at 4 is fine, but we do want to make a semi
concious choice on how we map back to those 4.
next prev parent reply other threads:[~2016-05-24 9:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-24 3:57 [PATCH] x86/traps: Don't for in_interrupt() to return true in IST handlers Andy Lutomirski
2016-05-24 8:59 ` Peter Zijlstra
2016-05-24 9:36 ` Borislav Petkov
2016-05-24 9:51 ` Peter Zijlstra [this message]
2016-05-24 15:43 ` Andy Lutomirski
2016-05-24 17:09 ` Peter Zijlstra
2016-05-24 18:54 ` Andy Lutomirski
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