linux-kernel - [PATCH] [16/36] CPA: Change 32bit back to init

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Date:	Wed, 16 Jan 2008 23:15:15 +0100 (CET)
From:	Andi Kleen <ak@...e.de>
To:	linux-kernel@...r.kernel.org, mingo@...e.hu, tglx@...utronix.de,
	jbeulich@...ell.com, venkatesh.pallipadi@...el.com
Subject: [PATCH] [16/36] CPA: Change 32bit back to init_mm semaphore locking


Now that debug pagealloc uses a separate function it is better
to change standard change_page_attr back to init_mm semaphore locking like 64bit.
Various things are simpler when sleeping is allowed.

Signed-off-by: Andi Kleen <ak@...e.de>
Acked-by: Jan Beulich <jbeulich@...ell.com>

---
 arch/x86/mm/pageattr_32.c |   14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

Index: linux/arch/x86/mm/pageattr_32.c
===================================================================
--- linux.orig/arch/x86/mm/pageattr_32.c
+++ linux/arch/x86/mm/pageattr_32.c
@@ -14,10 +14,9 @@
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
 
-static DEFINE_SPINLOCK(cpa_lock);
+/* Protected by init_mm.mmap_sem */
 static struct list_head df_list = LIST_HEAD_INIT(df_list);
 
-
 pte_t *lookup_address(unsigned long address, int *level)
 { 
 	pgd_t *pgd = pgd_offset_k(address);
@@ -46,9 +45,7 @@ static struct page *split_large_page(uns
 	struct page *base;
 	pte_t *pbase;
 
-	spin_unlock_irq(&cpa_lock);
 	base = alloc_pages(GFP_KERNEL, 0);
-	spin_lock_irq(&cpa_lock);
 	if (!base) 
 		return NULL;
 
@@ -224,15 +221,14 @@ int change_page_attr(struct page *page, 
 {
 	int err = 0; 
 	int i; 
-	unsigned long flags;
 
-	spin_lock_irqsave(&cpa_lock, flags);
+	down_write(&init_mm.mmap_sem);
 	for (i = 0; i < numpages; i++, page++) { 
 		err = __change_page_attr(page, prot);
 		if (err) 
 			break; 
 	}	
-	spin_unlock_irqrestore(&cpa_lock, flags);
+	up_write(&init_mm.mmap_sem);
 	return err;
 }
 
@@ -259,9 +255,9 @@ void global_flush_tlb(void)
 
 	BUG_ON(irqs_disabled());
 
-	spin_lock_irq(&cpa_lock);
+	down_write(&init_mm.mmap_sem);
 	list_replace_init(&df_list, &l);
-	spin_unlock_irq(&cpa_lock);
+	up_write(&init_mm.mmap_sem);
 	flush_map(&l);
 	list_for_each_entry_safe(pg, next, &l, lru) {
 		list_del(&pg->lru);
--
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