From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
stable-rt@vger.kernel.org
Subject: [PATCH RT v2] x86/mm/pat: disable preemption __split_large_page() after spin_lock()
Date: Thu, 13 Dec 2018 21:37:46 +0100 [thread overview]
Message-ID: <20181213203746.m7oq3erumlyqckwi@linutronix.de> (raw)
In-Reply-To: <20181213125907.48e75b89@gandalf.local.home>
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 __flush_tlb_all().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
v1…v2:
- add comment
- enable preemption before dropping the spinlock
arch/x86/mm/pageattr.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -688,11 +688,17 @@ static int
spin_lock(&pgd_lock);
/*
+ * Keep preemption disabled after __flush_tlb_all() which expects not be
+ * preempted during the flush of the local TLB.
+ */
+ preempt_disable();
+ /*
* Check for races, another CPU might have split this page
* up for us already:
*/
tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte) {
+ preempt_enable();
spin_unlock(&pgd_lock);
return 1;
}
@@ -726,6 +732,7 @@ static int
break;
default:
+ preempt_enable();
spin_unlock(&pgd_lock);
return 1;
}
@@ -764,6 +771,7 @@ static int
* going on.
*/
__flush_tlb_all();
+ preempt_enable();
spin_unlock(&pgd_lock);
return 0;
next prev parent reply other threads:[~2018-12-13 20:37 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 ` Sebastian Andrzej Siewior [this message]
2019-01-09 0:39 ` Scott Wood
2019-01-09 8:48 ` Sebastian Andrzej Siewior
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