From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: 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: [PATCH RT] x86/mm/pat: disable preemption __split_large_page() after spin_lock()
Date: Thu, 13 Dec 2018 17:44:31 +0100 [thread overview]
Message-ID: <20181213164430.mggilzfjgr5retz6@linutronix.de> (raw)
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>
---
arch/x86/mm/pageattr.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index e2d4b25c7aa44..abbe3e93ec266 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -687,6 +687,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
pgprot_t ref_prot;
spin_lock(&pgd_lock);
+ preempt_disable();
/*
* Check for races, another CPU might have split this page
* up for us already:
@@ -694,6 +695,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte) {
spin_unlock(&pgd_lock);
+ preempt_enable();
return 1;
}
@@ -727,6 +729,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
default:
spin_unlock(&pgd_lock);
+ preempt_enable();
return 1;
}
@@ -764,6 +767,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
* going on.
*/
__flush_tlb_all();
+ preempt_enable();
spin_unlock(&pgd_lock);
return 0;
--
2.20.0
next reply other threads:[~2018-12-13 16:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 16:44 Sebastian Andrzej Siewior [this message]
2018-12-13 17:59 ` [PATCH RT] x86/mm/pat: disable preemption __split_large_page() after spin_lock() 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 ` [PATCH RT] " Scott Wood
2019-01-09 8:48 ` Sebastian Andrzej Siewior
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