From: Michal Hocko <mhocko@suse.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
"Paul E . McKenney" <paulmck@kernel.org>,
Shakeel Butt <shakeelb@google.com>,
tglx@linutronix.de, john.ogness@linutronix.de, urezki@gmail.com,
ast@fb.com, Eric Dumazet <edumazet@google.com>,
Mina Almasry <almasrymina@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] hugetlb: select PREEMPT_COUNT if HUGETLB_PAGE for in_atomic use
Date: Thu, 11 Mar 2021 10:01:22 +0100 [thread overview]
Message-ID: <YEncYrWCVn2/20/C@dhcp22.suse.cz> (raw)
In-Reply-To: <YEnY5hWLT/en7kw1@hirez.programming.kicks-ass.net>
On Thu 11-03-21 09:46:30, Peter Zijlstra wrote:
> On Wed, Mar 10, 2021 at 06:13:21PM -0800, Mike Kravetz wrote:
> > from irq context. Changing the check in the code from !in_task to
> > in_atomic would handle the situations when called with irqs disabled.
>
> It does not. local_irq_disable() does not change preempt_count().
You are right. Earlier I was suggesting to check of irq_disabled() as
well http://lkml.kernel.org/r/YD4I+VPr3UNt063H@dhcp22.suse.cz
back then it was not really clear to me that in fact we do care about
spin locks more than irq disabled code. I am not even sure whether we
need to care about irq disabled regions without any locks held that
wouldn't be covered by in_atomic. But it would be safer to add
irq_disabled check as well.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-03-11 9:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-11 2:13 Mike Kravetz
2021-03-11 5:43 ` Andrew Morton
2021-03-11 8:20 ` Michal Hocko
2021-03-11 8:26 ` Michal Hocko
2021-03-11 8:27 ` Michal Hocko
2021-03-11 8:46 ` Peter Zijlstra
2021-03-11 9:01 ` Michal Hocko [this message]
2021-03-11 9:32 ` Peter Zijlstra
2021-03-11 9:44 ` Michal Hocko
2021-03-11 9:52 ` Peter Zijlstra
2021-03-11 11:09 ` Michal Hocko
2021-03-11 11:36 ` Peter Zijlstra
2021-03-11 12:02 ` Michal Hocko
2021-03-11 17:25 ` Mike Kravetz
2021-03-11 12:49 ` Michal Hocko
2021-03-11 17:50 ` Paul E. McKenney
2021-03-11 9:49 ` Peter Zijlstra
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