From: Scott Wood <swood@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-rt-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
stable-rt@vger.kernel.org
Subject: Re: [PATCH RT] x86/mm/pat: disable preemption __split_large_page() after spin_lock()
Date: Tue, 08 Jan 2019 18:39:15 -0600 [thread overview]
Message-ID: <1546994355.3632.15.camel@redhat.com> (raw)
In-Reply-To: <20181213164430.mggilzfjgr5retz6@linutronix.de>
On Thu, 2018-12-13 at 17:44 +0100, Sebastian Andrzej Siewior wrote:
> Commit "x86/mm/pat: Disable preemption around __flush_tlb_all()" added a
> warning if __flush_tlb_all() is invoked in preemptible context. On !RT
> the warning does not trigger because a spin lock is acquired which
> disables preemption. On RT the spin lock does not disable preemption and
> so the warning is seen.
>
> Disable preemption to avoid the warning in __flush_tlb_all().
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
FWIW, that __flush_tlb_all() can probably just be removed. It was added as
a partial workaround for an erratum, but since it didn't completely solve
the problem, hugepages were disabled on the affected chips in commit
7a0fc404ae66377 ("x86: Disable large pages on CPUs with Atom erratum
AAE44"). I was going to send a (non-RT) patch removing the flush but in
4.20 commit c0a759abf5a68 ("x86/mm/cpa: Move flush_tlb_all()") reworked the
code to make it moot.
-Scott
next prev parent reply other threads:[~2019-01-09 0:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 16:44 [PATCH RT] x86/mm/pat: disable preemption __split_large_page() after spin_lock() Sebastian Andrzej Siewior
2018-12-13 17:59 ` Steven Rostedt
2018-12-13 18:27 ` Sebastian Andrzej Siewior
2018-12-13 20:37 ` [PATCH RT v2] " Sebastian Andrzej Siewior
2019-01-09 0:39 ` Scott Wood [this message]
2019-01-09 8:48 ` [PATCH RT] " Sebastian Andrzej Siewior
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