2018-12-14 09:55:05 +00:00
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Tue, 11 Dec 2018 21:53:43 +0100
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Subject: [PATCH] x86/mm/pat: disable preemption __split_large_page() after
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spin_lock()
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2019-02-27 18:51:46 +00:00
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.25-rt16.tar.xz
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2018-12-14 09:55:05 +00:00
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Commit "x86/mm/pat: Disable preemption around __flush_tlb_all()" added a
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warning if __flush_tlb_all() is invoked in preemptible context. On !RT
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the warning does not trigger because a spin lock is acquired which
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disables preemption. On RT the spin lock does not disable preemption and
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so the warning is seen.
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Disable preemption to avoid the warning __flush_tlb_all().
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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arch/x86/mm/pageattr.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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--- a/arch/x86/mm/pageattr.c
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+++ b/arch/x86/mm/pageattr.c
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@@ -688,11 +688,17 @@ static int
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spin_lock(&pgd_lock);
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/*
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+ * Keep preemption disabled after __flush_tlb_all() which expects not be
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+ * preempted during the flush of the local TLB.
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+ */
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+ preempt_disable();
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+ /*
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* Check for races, another CPU might have split this page
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* up for us already:
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*/
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tmp = _lookup_address_cpa(cpa, address, &level);
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if (tmp != kpte) {
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+ preempt_enable();
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spin_unlock(&pgd_lock);
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return 1;
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}
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@@ -726,6 +732,7 @@ static int
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break;
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default:
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+ preempt_enable();
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spin_unlock(&pgd_lock);
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return 1;
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}
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@@ -764,6 +771,7 @@ static int
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* going on.
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*/
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__flush_tlb_all();
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+ preempt_enable();
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spin_unlock(&pgd_lock);
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return 0;
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