linux-kernel - [PATCH powerpc 1/2] powerpc: protect per-CPU access with preempt

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Date:	Thu, 10 Feb 2011 13:57:26 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	benh@...nel.crashing.org, paulus@...ba.org
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH powerpc 1/2] powerpc: protect per-CPU access with preempt_disable

The hpte_need_flush() function accesses the ppc64_tlb_batch per-CPU
variable with preemption enabled, a bug that this patch fixes.  Perhaps
crudely.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 arch/powerpc/include/asm/pgtable-ppc64.h |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index 2b09cd5..6ed08ab 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -228,8 +228,11 @@ static inline unsigned long pte_update(struct mm_struct *mm,
 		assert_pte_locked(mm, addr);
 
 #ifdef CONFIG_PPC_STD_MMU_64
-	if (old & _PAGE_HASHPTE)
+	if (old & _PAGE_HASHPTE) {
+		preempt_disable();
 		hpte_need_flush(mm, addr, ptep, old, huge);
+		preempt_enable();
+	}
 #endif
 
 	return old;
-- 
1.7.3.2

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