66 lines
2.2 KiB
Diff
66 lines
2.2 KiB
Diff
From 4dd5348c4bdfbc53044d46d1d9ffb628b317576b Mon Sep 17 00:00:00 2001
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Message-Id: <4dd5348c4bdfbc53044d46d1d9ffb628b317576b.1601675151.git.zanussi@kernel.org>
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In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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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 087/333] x86/mm/pat: disable preemption __split_large_page()
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after spin_lock()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.tar.xz
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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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diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
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index 101f3ad0d6ad..0b0396261ca1 100644
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--- a/arch/x86/mm/pageattr.c
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+++ b/arch/x86/mm/pageattr.c
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@@ -687,12 +687,18 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
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pgprot_t ref_prot;
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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 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
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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 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
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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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--
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2.17.1
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