Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1325039 > unrolled thread

[PATCH v4 2/4] x86: query dynamic DEBUG_PAGEALLOC setting

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH v4 2/4] x86: query dynamic DEBUG_PAGEALLOC setting Christian Borntraeger <borntraeger@de.ibm.com> - 2016-02-03 09:40 +0100
    Re: [PATCH v4 2/4] x86: query dynamic DEBUG_PAGEALLOC setting David Rientjes <rientjes@google.com> - 2016-02-03 23:50 +0100

#1325039 — [PATCH v4 2/4] x86: query dynamic DEBUG_PAGEALLOC setting

We can use debug_pagealloc_enabled() to check if we can map
the identity mapping with 2MB pages. We can also add the state
into the dump_stack output.

The patch does not touch the code for the 1GB pages, which ignored
CONFIG_DEBUG_PAGEALLOC. Do we need to fence this as well?

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/dumpstack.c |  5 ++---
 arch/x86/mm/init.c          |  7 ++++---
 arch/x86/mm/pageattr.c      | 14 ++++----------
 3 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 9c30acf..32e5699 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -265,9 +265,8 @@ int __die(const char *str, struct pt_regs *regs, long err)
 #ifdef CONFIG_SMP
 	printk("SMP ");
 #endif
-#ifdef CONFIG_DEBUG_PAGEALLOC
-	printk("DEBUG_PAGEALLOC ");
-#endif
+	if (debug_pagealloc_enabled())
+		printk("DEBUG_PAGEALLOC ");
 #ifdef CONFIG_KASAN
 	printk("KASAN");
 #endif
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 493f541..39823fd 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -150,13 +150,14 @@ static int page_size_mask;
 
 static void __init probe_page_size_mask(void)
 {
-#if !defined(CONFIG_DEBUG_PAGEALLOC) && !defined(CONFIG_KMEMCHECK)
+#if !defined(CONFIG_KMEMCHECK)
 	/*
-	 * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
+	 * For CONFIG_KMEMCHECK or pagealloc debugging, identity mapping will
+	 * use small pages.
 	 * This will simplify cpa(), which otherwise needs to support splitting
 	 * large pages into small in interrupt context, etc.
 	 */
-	if (cpu_has_pse)
+	if (cpu_has_pse && !debug_pagealloc_enabled())
 		page_size_mask |= 1 << PG_LEVEL_2M;
 #endif
 
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 2440814..1ef9c2c 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -106,12 +106,6 @@ static inline unsigned long highmap_end_pfn(void)
 
 #endif
 
-#ifdef CONFIG_DEBUG_PAGEALLOC
-# define debug_pagealloc 1
-#else
-# define debug_pagealloc 0
-#endif
-
 static inline int
 within(unsigned long addr, unsigned long start, unsigned long end)
 {
@@ -708,10 +702,10 @@ static int split_large_page(struct cpa_data *cpa, pte_t *kpte,
 {
 	struct page *base;
 
-	if (!debug_pagealloc)
+	if (!debug_pagealloc_enabled())
 		spin_unlock(&cpa_lock);
 	base = alloc_pages(GFP_KERNEL | __GFP_NOTRACK, 0);
-	if (!debug_pagealloc)
+	if (!debug_pagealloc_enabled())
 		spin_lock(&cpa_lock);
 	if (!base)
 		return -ENOMEM;
@@ -1331,10 +1325,10 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias)
 		if (cpa->flags & (CPA_ARRAY | CPA_PAGES_ARRAY))
 			cpa->numpages = 1;
 
-		if (!debug_pagealloc)
+		if (!debug_pagealloc_enabled())
 			spin_lock(&cpa_lock);
 		ret = __change_page_attr(cpa, checkalias);
-		if (!debug_pagealloc)
+		if (!debug_pagealloc_enabled())
 			spin_unlock(&cpa_lock);
 		if (ret)
 			return ret;
-- 
2.3.0

[toc] | [next] | [standalone]

#1326057

On Wed, 3 Feb 2016, Christian Borntraeger wrote:

> We can use debug_pagealloc_enabled() to check if we can map
> the identity mapping with 2MB pages. We can also add the state
> into the dump_stack output.
> 
> The patch does not touch the code for the 1GB pages, which ignored
> CONFIG_DEBUG_PAGEALLOC. Do we need to fence this as well?
> 

I think it would be an extension of the debug_pagealloc= functionality and 
can certainly be introduced if someone is inclined.

> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Acked-by: David Rientjes <rientjes@google.com>

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web