linux-kernel - [PATCH 1/8] mm: disable preemption in apply_to_pte

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Date:	Fri, 27 Mar 2009 11:02:36 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	the arch/x86 maintainers <x86@...nel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: [PATCH 1/8] mm: disable preemption in apply_to_pte_range

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>

Impact: bugfix

Lazy mmu mode needs preemption disabled, so if we're apply to
init_mm (which doesn't require any pte locks), then explicitly
disable preemption.  (Do it unconditionally after checking we've
successfully done the allocation to simplify the error handling.)

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
 mm/memory.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index ef11ac6..27f8677 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1722,6 +1722,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
 
 	BUG_ON(pmd_huge(*pmd));
 
+	preempt_disable();
 	arch_enter_lazy_mmu_mode();
 
 	token = pmd_pgtable(*pmd);
@@ -1733,6 +1734,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 
 	arch_leave_lazy_mmu_mode();
+	preempt_enable();
 
 	if (mm != &init_mm)
 		pte_unmap_unlock(pte-1, ptl);
-- 
1.6.0.6

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