* [PATCH/RFC 0/3] Optimize CONFIG_DEBUG_PAGEALLOC
@ 2016-01-26 9:18 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
As CONFIG_DEBUG_PAGEALLOC can be enabled/disabled via kernel
parameters we can optimize some cases by checking the enablement
state.
I have done s390 and x86 as examples. Other architecture can
provide followup patches later on.
Christian Borntraeger (3):
mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC
x86: query dynamic DEBUG_PAGEALLOC setting
s390: query dynamic DEBUG_PAGEALLOC setting
arch/s390/kernel/dumpstack.c | 4 +++-
arch/s390/mm/vmem.c | 10 ++++------
arch/x86/kernel/dumpstack.c | 4 +++-
arch/x86/mm/init.c | 7 ++++---
arch/x86/mm/pageattr.c | 14 ++++----------
include/linux/mm.h | 4 ++++
6 files changed, 22 insertions(+), 21 deletions(-)
--
2.3.0
^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH/RFC 0/3] Optimize CONFIG_DEBUG_PAGEALLOC
@ 2016-01-26 9:18 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
As CONFIG_DEBUG_PAGEALLOC can be enabled/disabled via kernel
parameters we can optimize some cases by checking the enablement
state.
I have done s390 and x86 as examples. Other architecture can
provide followup patches later on.
Christian Borntraeger (3):
mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC
x86: query dynamic DEBUG_PAGEALLOC setting
s390: query dynamic DEBUG_PAGEALLOC setting
arch/s390/kernel/dumpstack.c | 4 +++-
arch/s390/mm/vmem.c | 10 ++++------
arch/x86/kernel/dumpstack.c | 4 +++-
arch/x86/mm/init.c | 7 ++++---
arch/x86/mm/pageattr.c | 14 ++++----------
include/linux/mm.h | 4 ++++
6 files changed, 22 insertions(+), 21 deletions(-)
--
2.3.0
--
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^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH/RFC 1/3] mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC
2016-01-26 9:18 ` Christian Borntraeger
@ 2016-01-26 9:18 ` Christian Borntraeger
-1 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
We can provide debug_pagealloc_enabled() also if CONFIG_DEBUG_PAGEALLOC
is not set. It will return false in that case.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
include/linux/mm.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7783073..fbc5354 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2148,6 +2148,10 @@ kernel_map_pages(struct page *page, int numpages, int enable)
extern bool kernel_page_present(struct page *page);
#endif /* CONFIG_HIBERNATION */
#else
+static inline bool debug_pagealloc_enabled(void)
+{
+ return false;
+}
static inline void
kernel_map_pages(struct page *page, int numpages, int enable) {}
#ifdef CONFIG_HIBERNATION
--
2.3.0
^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH/RFC 1/3] mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC
@ 2016-01-26 9:18 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
We can provide debug_pagealloc_enabled() also if CONFIG_DEBUG_PAGEALLOC
is not set. It will return false in that case.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
include/linux/mm.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7783073..fbc5354 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2148,6 +2148,10 @@ kernel_map_pages(struct page *page, int numpages, int enable)
extern bool kernel_page_present(struct page *page);
#endif /* CONFIG_HIBERNATION */
#else
+static inline bool debug_pagealloc_enabled(void)
+{
+ return false;
+}
static inline void
kernel_map_pages(struct page *page, int numpages, int enable) {}
#ifdef CONFIG_HIBERNATION
--
2.3.0
--
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^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH/RFC 2/3] x86: query dynamic DEBUG_PAGEALLOC setting
2016-01-26 9:18 ` Christian Borntraeger
@ 2016-01-26 9:18 ` Christian Borntraeger
-1 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
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>
---
arch/x86/kernel/dumpstack.c | 4 +++-
arch/x86/mm/init.c | 7 ++++---
arch/x86/mm/pageattr.c | 14 ++++----------
3 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 9c30acf..7971638 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -266,7 +266,9 @@ int __die(const char *str, struct pt_regs *regs, long err)
printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
- printk("DEBUG_PAGEALLOC ");
+ printk("DEBUG_PAGEALLOC(%s) ",
+ debug_pagealloc_enabled() ? "enabled" : "disabled");
+
#endif
#ifdef CONFIG_KASAN
printk("KASAN");
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 a3137a4..a49c8fd 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -103,12 +103,6 @@ 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)
{
@@ -703,10 +697,10 @@ 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;
@@ -1326,10 +1320,10 @@ 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
^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH/RFC 2/3] x86: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-26 9:18 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
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>
---
arch/x86/kernel/dumpstack.c | 4 +++-
arch/x86/mm/init.c | 7 ++++---
arch/x86/mm/pageattr.c | 14 ++++----------
3 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 9c30acf..7971638 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -266,7 +266,9 @@ int __die(const char *str, struct pt_regs *regs, long err)
printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
- printk("DEBUG_PAGEALLOC ");
+ printk("DEBUG_PAGEALLOC(%s) ",
+ debug_pagealloc_enabled() ? "enabled" : "disabled");
+
#endif
#ifdef CONFIG_KASAN
printk("KASAN");
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 a3137a4..a49c8fd 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -103,12 +103,6 @@ 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)
{
@@ -703,10 +697,10 @@ 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;
@@ -1326,10 +1320,10 @@ 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
--
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^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-26 9:18 ` Christian Borntraeger
@ 2016-01-26 9:18 ` Christian Borntraeger
-1 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
We can use debug_pagealloc_enabled() to check if we can map
the identity mapping with 1MB/2GB pages as well as to print
the current setting in dump_stack.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/kernel/dumpstack.c | 4 +++-
arch/s390/mm/vmem.c | 10 ++++------
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
index dc8e204..a1c0530 100644
--- a/arch/s390/kernel/dumpstack.c
+++ b/arch/s390/kernel/dumpstack.c
@@ -11,6 +11,7 @@
#include <linux/export.h>
#include <linux/kdebug.h>
#include <linux/ptrace.h>
+#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <asm/processor.h>
@@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
- printk("DEBUG_PAGEALLOC");
+ printk("DEBUG_PAGEALLOC(%s)",
+ debug_pagealloc_enabled() ? "enabled" : "disabled");
#endif
printk("\n");
notify_die(DIE_OOPS, str, regs, 0, regs->int_code & 0xffff, SIGSEGV);
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index ef7d6c8..d27fccba 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -94,16 +94,15 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
pgd_populate(&init_mm, pg_dir, pu_dir);
}
pu_dir = pud_offset(pg_dir, address);
-#ifndef CONFIG_DEBUG_PAGEALLOC
if (MACHINE_HAS_EDAT2 && pud_none(*pu_dir) && address &&
- !(address & ~PUD_MASK) && (address + PUD_SIZE <= end)) {
+ !(address & ~PUD_MASK) && (address + PUD_SIZE <= end) &&
+ !debug_pagealloc_enabled()) {
pud_val(*pu_dir) = __pa(address) |
_REGION_ENTRY_TYPE_R3 | _REGION3_ENTRY_LARGE |
(ro ? _REGION_ENTRY_PROTECT : 0);
address += PUD_SIZE;
continue;
}
-#endif
if (pud_none(*pu_dir)) {
pm_dir = vmem_pmd_alloc();
if (!pm_dir)
@@ -111,9 +110,9 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
pud_populate(&init_mm, pu_dir, pm_dir);
}
pm_dir = pmd_offset(pu_dir, address);
-#ifndef CONFIG_DEBUG_PAGEALLOC
if (MACHINE_HAS_EDAT1 && pmd_none(*pm_dir) && address &&
- !(address & ~PMD_MASK) && (address + PMD_SIZE <= end)) {
+ !(address & ~PMD_MASK) && (address + PMD_SIZE <= end) &&
+ !debug_pagealloc_enabled()) {
pmd_val(*pm_dir) = __pa(address) |
_SEGMENT_ENTRY | _SEGMENT_ENTRY_LARGE |
_SEGMENT_ENTRY_YOUNG |
@@ -121,7 +120,6 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
address += PMD_SIZE;
continue;
}
-#endif
if (pmd_none(*pm_dir)) {
pt_dir = vmem_pte_alloc(address);
if (!pt_dir)
--
2.3.0
^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-26 9:18 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-26 9:18 UTC (permalink / raw)
To: linux-kernel
Cc: akpm, linux-mm, linux-arch, linux-s390, x86, Christian Borntraeger
We can use debug_pagealloc_enabled() to check if we can map
the identity mapping with 1MB/2GB pages as well as to print
the current setting in dump_stack.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/kernel/dumpstack.c | 4 +++-
arch/s390/mm/vmem.c | 10 ++++------
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
index dc8e204..a1c0530 100644
--- a/arch/s390/kernel/dumpstack.c
+++ b/arch/s390/kernel/dumpstack.c
@@ -11,6 +11,7 @@
#include <linux/export.h>
#include <linux/kdebug.h>
#include <linux/ptrace.h>
+#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <asm/processor.h>
@@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
- printk("DEBUG_PAGEALLOC");
+ printk("DEBUG_PAGEALLOC(%s)",
+ debug_pagealloc_enabled() ? "enabled" : "disabled");
#endif
printk("\n");
notify_die(DIE_OOPS, str, regs, 0, regs->int_code & 0xffff, SIGSEGV);
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index ef7d6c8..d27fccba 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -94,16 +94,15 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
pgd_populate(&init_mm, pg_dir, pu_dir);
}
pu_dir = pud_offset(pg_dir, address);
-#ifndef CONFIG_DEBUG_PAGEALLOC
if (MACHINE_HAS_EDAT2 && pud_none(*pu_dir) && address &&
- !(address & ~PUD_MASK) && (address + PUD_SIZE <= end)) {
+ !(address & ~PUD_MASK) && (address + PUD_SIZE <= end) &&
+ !debug_pagealloc_enabled()) {
pud_val(*pu_dir) = __pa(address) |
_REGION_ENTRY_TYPE_R3 | _REGION3_ENTRY_LARGE |
(ro ? _REGION_ENTRY_PROTECT : 0);
address += PUD_SIZE;
continue;
}
-#endif
if (pud_none(*pu_dir)) {
pm_dir = vmem_pmd_alloc();
if (!pm_dir)
@@ -111,9 +110,9 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
pud_populate(&init_mm, pu_dir, pm_dir);
}
pm_dir = pmd_offset(pu_dir, address);
-#ifndef CONFIG_DEBUG_PAGEALLOC
if (MACHINE_HAS_EDAT1 && pmd_none(*pm_dir) && address &&
- !(address & ~PMD_MASK) && (address + PMD_SIZE <= end)) {
+ !(address & ~PMD_MASK) && (address + PMD_SIZE <= end) &&
+ !debug_pagealloc_enabled()) {
pmd_val(*pm_dir) = __pa(address) |
_SEGMENT_ENTRY | _SEGMENT_ENTRY_LARGE |
_SEGMENT_ENTRY_YOUNG |
@@ -121,7 +120,6 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
address += PMD_SIZE;
continue;
}
-#endif
if (pmd_none(*pm_dir)) {
pt_dir = vmem_pte_alloc(address);
if (!pt_dir)
--
2.3.0
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply related [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-26 9:18 ` Christian Borntraeger
@ 2016-01-26 18:19 ` Heiko Carstens
-1 siblings, 0 replies; 34+ messages in thread
From: Heiko Carstens @ 2016-01-26 18:19 UTC (permalink / raw)
To: Christian Borntraeger
Cc: linux-kernel, akpm, linux-mm, linux-arch, linux-s390, x86
On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> We can use debug_pagealloc_enabled() to check if we can map
> the identity mapping with 1MB/2GB pages as well as to print
> the current setting in dump_stack.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/kernel/dumpstack.c | 4 +++-
> arch/s390/mm/vmem.c | 10 ++++------
> 2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> index dc8e204..a1c0530 100644
> --- a/arch/s390/kernel/dumpstack.c
> +++ b/arch/s390/kernel/dumpstack.c
> @@ -11,6 +11,7 @@
> #include <linux/export.h>
> #include <linux/kdebug.h>
> #include <linux/ptrace.h>
> +#include <linux/mm.h>
> #include <linux/module.h>
> #include <linux/sched.h>
> #include <asm/processor.h>
> @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> printk("SMP ");
> #endif
> #ifdef CONFIG_DEBUG_PAGEALLOC
> - printk("DEBUG_PAGEALLOC");
> + printk("DEBUG_PAGEALLOC(%s)",
> + debug_pagealloc_enabled() ? "enabled" : "disabled");
> #endif
I'd prefer if you change this to
if (debug_pagealloc_enabled())
printk("DEBUG_PAGEALLOC");
That way we can get rid of yet another ifdef. Having
"DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-26 18:19 ` Heiko Carstens
0 siblings, 0 replies; 34+ messages in thread
From: Heiko Carstens @ 2016-01-26 18:19 UTC (permalink / raw)
To: Christian Borntraeger
Cc: linux-kernel, akpm, linux-mm, linux-arch, linux-s390, x86
On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> We can use debug_pagealloc_enabled() to check if we can map
> the identity mapping with 1MB/2GB pages as well as to print
> the current setting in dump_stack.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/kernel/dumpstack.c | 4 +++-
> arch/s390/mm/vmem.c | 10 ++++------
> 2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> index dc8e204..a1c0530 100644
> --- a/arch/s390/kernel/dumpstack.c
> +++ b/arch/s390/kernel/dumpstack.c
> @@ -11,6 +11,7 @@
> #include <linux/export.h>
> #include <linux/kdebug.h>
> #include <linux/ptrace.h>
> +#include <linux/mm.h>
> #include <linux/module.h>
> #include <linux/sched.h>
> #include <asm/processor.h>
> @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> printk("SMP ");
> #endif
> #ifdef CONFIG_DEBUG_PAGEALLOC
> - printk("DEBUG_PAGEALLOC");
> + printk("DEBUG_PAGEALLOC(%s)",
> + debug_pagealloc_enabled() ? "enabled" : "disabled");
> #endif
I'd prefer if you change this to
if (debug_pagealloc_enabled())
printk("DEBUG_PAGEALLOC");
That way we can get rid of yet another ifdef. Having
"DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-26 18:19 ` Heiko Carstens
@ 2016-01-26 20:38 ` Thomas Gleixner
-1 siblings, 0 replies; 34+ messages in thread
From: Thomas Gleixner @ 2016-01-26 20:38 UTC (permalink / raw)
To: Heiko Carstens
Cc: Christian Borntraeger, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On Tue, 26 Jan 2016, Heiko Carstens wrote:
> On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> > We can use debug_pagealloc_enabled() to check if we can map
> > the identity mapping with 1MB/2GB pages as well as to print
> > the current setting in dump_stack.
> >
> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > ---
> > arch/s390/kernel/dumpstack.c | 4 +++-
> > arch/s390/mm/vmem.c | 10 ++++------
> > 2 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> > index dc8e204..a1c0530 100644
> > --- a/arch/s390/kernel/dumpstack.c
> > +++ b/arch/s390/kernel/dumpstack.c
> > @@ -11,6 +11,7 @@
> > #include <linux/export.h>
> > #include <linux/kdebug.h>
> > #include <linux/ptrace.h>
> > +#include <linux/mm.h>
> > #include <linux/module.h>
> > #include <linux/sched.h>
> > #include <asm/processor.h>
> > @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> > printk("SMP ");
> > #endif
> > #ifdef CONFIG_DEBUG_PAGEALLOC
> > - printk("DEBUG_PAGEALLOC");
> > + printk("DEBUG_PAGEALLOC(%s)",
> > + debug_pagealloc_enabled() ? "enabled" : "disabled");
> > #endif
>
> I'd prefer if you change this to
>
> if (debug_pagealloc_enabled())
> printk("DEBUG_PAGEALLOC");
>
> That way we can get rid of yet another ifdef. Having
> "DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
Yes, same for x86 please.
Thanks,
tglx
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-26 20:38 ` Thomas Gleixner
0 siblings, 0 replies; 34+ messages in thread
From: Thomas Gleixner @ 2016-01-26 20:38 UTC (permalink / raw)
To: Heiko Carstens
Cc: Christian Borntraeger, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On Tue, 26 Jan 2016, Heiko Carstens wrote:
> On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> > We can use debug_pagealloc_enabled() to check if we can map
> > the identity mapping with 1MB/2GB pages as well as to print
> > the current setting in dump_stack.
> >
> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > ---
> > arch/s390/kernel/dumpstack.c | 4 +++-
> > arch/s390/mm/vmem.c | 10 ++++------
> > 2 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> > index dc8e204..a1c0530 100644
> > --- a/arch/s390/kernel/dumpstack.c
> > +++ b/arch/s390/kernel/dumpstack.c
> > @@ -11,6 +11,7 @@
> > #include <linux/export.h>
> > #include <linux/kdebug.h>
> > #include <linux/ptrace.h>
> > +#include <linux/mm.h>
> > #include <linux/module.h>
> > #include <linux/sched.h>
> > #include <asm/processor.h>
> > @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> > printk("SMP ");
> > #endif
> > #ifdef CONFIG_DEBUG_PAGEALLOC
> > - printk("DEBUG_PAGEALLOC");
> > + printk("DEBUG_PAGEALLOC(%s)",
> > + debug_pagealloc_enabled() ? "enabled" : "disabled");
> > #endif
>
> I'd prefer if you change this to
>
> if (debug_pagealloc_enabled())
> printk("DEBUG_PAGEALLOC");
>
> That way we can get rid of yet another ifdef. Having
> "DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
Yes, same for x86 please.
Thanks,
tglx
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 1/3] mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC
2016-01-26 9:18 ` Christian Borntraeger
@ 2016-01-26 23:23 ` David Rientjes
-1 siblings, 0 replies; 34+ messages in thread
From: David Rientjes @ 2016-01-26 23:23 UTC (permalink / raw)
To: Christian Borntraeger
Cc: linux-kernel, akpm, linux-mm, linux-arch, linux-s390, x86
On Tue, 26 Jan 2016, Christian Borntraeger wrote:
> We can provide debug_pagealloc_enabled() also if CONFIG_DEBUG_PAGEALLOC
> is not set. It will return false in that case.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> include/linux/mm.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7783073..fbc5354 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2148,6 +2148,10 @@ kernel_map_pages(struct page *page, int numpages, int enable)
> extern bool kernel_page_present(struct page *page);
> #endif /* CONFIG_HIBERNATION */
> #else
> +static inline bool debug_pagealloc_enabled(void)
> +{
> + return false;
> +}
> static inline void
> kernel_map_pages(struct page *page, int numpages, int enable) {}
> #ifdef CONFIG_HIBERNATION
Since the patchset needs to be refreshed based on Heiko and Thomas's
comments, please add some /* CONFIG_DEBUG_PAGEALLOC */ annotation to the
#else and #endif lines so this block is easier to read. After that, feel
free to add
Acked-by: David Rientjes <rientjes@google.com>
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 1/3] mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC
@ 2016-01-26 23:23 ` David Rientjes
0 siblings, 0 replies; 34+ messages in thread
From: David Rientjes @ 2016-01-26 23:23 UTC (permalink / raw)
To: Christian Borntraeger
Cc: linux-kernel, akpm, linux-mm, linux-arch, linux-s390, x86
On Tue, 26 Jan 2016, Christian Borntraeger wrote:
> We can provide debug_pagealloc_enabled() also if CONFIG_DEBUG_PAGEALLOC
> is not set. It will return false in that case.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> include/linux/mm.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7783073..fbc5354 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2148,6 +2148,10 @@ kernel_map_pages(struct page *page, int numpages, int enable)
> extern bool kernel_page_present(struct page *page);
> #endif /* CONFIG_HIBERNATION */
> #else
> +static inline bool debug_pagealloc_enabled(void)
> +{
> + return false;
> +}
> static inline void
> kernel_map_pages(struct page *page, int numpages, int enable) {}
> #ifdef CONFIG_HIBERNATION
Since the patchset needs to be refreshed based on Heiko and Thomas's
comments, please add some /* CONFIG_DEBUG_PAGEALLOC */ annotation to the
#else and #endif lines so this block is easier to read. After that, feel
free to add
Acked-by: David Rientjes <rientjes@google.com>
--
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-26 18:19 ` Heiko Carstens
@ 2016-01-26 23:29 ` David Rientjes
-1 siblings, 0 replies; 34+ messages in thread
From: David Rientjes @ 2016-01-26 23:29 UTC (permalink / raw)
To: Heiko Carstens
Cc: Christian Borntraeger, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On Tue, 26 Jan 2016, Heiko Carstens wrote:
> On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> > We can use debug_pagealloc_enabled() to check if we can map
> > the identity mapping with 1MB/2GB pages as well as to print
> > the current setting in dump_stack.
> >
> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > ---
> > arch/s390/kernel/dumpstack.c | 4 +++-
> > arch/s390/mm/vmem.c | 10 ++++------
> > 2 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> > index dc8e204..a1c0530 100644
> > --- a/arch/s390/kernel/dumpstack.c
> > +++ b/arch/s390/kernel/dumpstack.c
> > @@ -11,6 +11,7 @@
> > #include <linux/export.h>
> > #include <linux/kdebug.h>
> > #include <linux/ptrace.h>
> > +#include <linux/mm.h>
> > #include <linux/module.h>
> > #include <linux/sched.h>
> > #include <asm/processor.h>
> > @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> > printk("SMP ");
> > #endif
> > #ifdef CONFIG_DEBUG_PAGEALLOC
> > - printk("DEBUG_PAGEALLOC");
> > + printk("DEBUG_PAGEALLOC(%s)",
> > + debug_pagealloc_enabled() ? "enabled" : "disabled");
> > #endif
>
> I'd prefer if you change this to
>
> if (debug_pagealloc_enabled())
> printk("DEBUG_PAGEALLOC");
>
> That way we can get rid of yet another ifdef. Having
> "DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
>
I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
also enables stackinfo storing and poisoning and it's not guarded by
debug_pagealloc_enabled().
It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
outside the scope of the debug_pagealloc=on kernel parameter, so
DEBUG_PAGEALLOC(disabled) actually does mean something.
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-26 23:29 ` David Rientjes
0 siblings, 0 replies; 34+ messages in thread
From: David Rientjes @ 2016-01-26 23:29 UTC (permalink / raw)
To: Heiko Carstens
Cc: Christian Borntraeger, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On Tue, 26 Jan 2016, Heiko Carstens wrote:
> On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> > We can use debug_pagealloc_enabled() to check if we can map
> > the identity mapping with 1MB/2GB pages as well as to print
> > the current setting in dump_stack.
> >
> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > ---
> > arch/s390/kernel/dumpstack.c | 4 +++-
> > arch/s390/mm/vmem.c | 10 ++++------
> > 2 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> > index dc8e204..a1c0530 100644
> > --- a/arch/s390/kernel/dumpstack.c
> > +++ b/arch/s390/kernel/dumpstack.c
> > @@ -11,6 +11,7 @@
> > #include <linux/export.h>
> > #include <linux/kdebug.h>
> > #include <linux/ptrace.h>
> > +#include <linux/mm.h>
> > #include <linux/module.h>
> > #include <linux/sched.h>
> > #include <asm/processor.h>
> > @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> > printk("SMP ");
> > #endif
> > #ifdef CONFIG_DEBUG_PAGEALLOC
> > - printk("DEBUG_PAGEALLOC");
> > + printk("DEBUG_PAGEALLOC(%s)",
> > + debug_pagealloc_enabled() ? "enabled" : "disabled");
> > #endif
>
> I'd prefer if you change this to
>
> if (debug_pagealloc_enabled())
> printk("DEBUG_PAGEALLOC");
>
> That way we can get rid of yet another ifdef. Having
> "DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
>
I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
also enables stackinfo storing and poisoning and it's not guarded by
debug_pagealloc_enabled().
It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
outside the scope of the debug_pagealloc=on kernel parameter, so
DEBUG_PAGEALLOC(disabled) actually does mean something.
--
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-26 23:29 ` David Rientjes
@ 2016-01-27 0:19 ` Joonsoo Kim
-1 siblings, 0 replies; 34+ messages in thread
From: Joonsoo Kim @ 2016-01-27 0:19 UTC (permalink / raw)
To: David Rientjes
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On Tue, Jan 26, 2016 at 03:29:38PM -0800, David Rientjes wrote:
> On Tue, 26 Jan 2016, Heiko Carstens wrote:
>
> > On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> > > We can use debug_pagealloc_enabled() to check if we can map
> > > the identity mapping with 1MB/2GB pages as well as to print
> > > the current setting in dump_stack.
> > >
> > > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > > ---
> > > arch/s390/kernel/dumpstack.c | 4 +++-
> > > arch/s390/mm/vmem.c | 10 ++++------
> > > 2 files changed, 7 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> > > index dc8e204..a1c0530 100644
> > > --- a/arch/s390/kernel/dumpstack.c
> > > +++ b/arch/s390/kernel/dumpstack.c
> > > @@ -11,6 +11,7 @@
> > > #include <linux/export.h>
> > > #include <linux/kdebug.h>
> > > #include <linux/ptrace.h>
> > > +#include <linux/mm.h>
> > > #include <linux/module.h>
> > > #include <linux/sched.h>
> > > #include <asm/processor.h>
> > > @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> > > printk("SMP ");
> > > #endif
> > > #ifdef CONFIG_DEBUG_PAGEALLOC
> > > - printk("DEBUG_PAGEALLOC");
> > > + printk("DEBUG_PAGEALLOC(%s)",
> > > + debug_pagealloc_enabled() ? "enabled" : "disabled");
> > > #endif
> >
> > I'd prefer if you change this to
> >
> > if (debug_pagealloc_enabled())
> > printk("DEBUG_PAGEALLOC");
> >
> > That way we can get rid of yet another ifdef. Having
> > "DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
> >
>
> I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
> debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
> When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
> also enables stackinfo storing and poisoning and it's not guarded by
> debug_pagealloc_enabled().
>
> It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
> outside the scope of the debug_pagealloc=on kernel parameter, so
> DEBUG_PAGEALLOC(disabled) actually does mean something.
Hello, David.
I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
http://thread.gmane.org/gmane.linux.kernel.mm/144527
I found that there are more sites to fix but not so many.
We can do it.
Thanks.
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 0:19 ` Joonsoo Kim
0 siblings, 0 replies; 34+ messages in thread
From: Joonsoo Kim @ 2016-01-27 0:19 UTC (permalink / raw)
To: David Rientjes
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On Tue, Jan 26, 2016 at 03:29:38PM -0800, David Rientjes wrote:
> On Tue, 26 Jan 2016, Heiko Carstens wrote:
>
> > On Tue, Jan 26, 2016 at 10:18:25AM +0100, Christian Borntraeger wrote:
> > > We can use debug_pagealloc_enabled() to check if we can map
> > > the identity mapping with 1MB/2GB pages as well as to print
> > > the current setting in dump_stack.
> > >
> > > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > > ---
> > > arch/s390/kernel/dumpstack.c | 4 +++-
> > > arch/s390/mm/vmem.c | 10 ++++------
> > > 2 files changed, 7 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
> > > index dc8e204..a1c0530 100644
> > > --- a/arch/s390/kernel/dumpstack.c
> > > +++ b/arch/s390/kernel/dumpstack.c
> > > @@ -11,6 +11,7 @@
> > > #include <linux/export.h>
> > > #include <linux/kdebug.h>
> > > #include <linux/ptrace.h>
> > > +#include <linux/mm.h>
> > > #include <linux/module.h>
> > > #include <linux/sched.h>
> > > #include <asm/processor.h>
> > > @@ -186,7 +187,8 @@ void die(struct pt_regs *regs, const char *str)
> > > printk("SMP ");
> > > #endif
> > > #ifdef CONFIG_DEBUG_PAGEALLOC
> > > - printk("DEBUG_PAGEALLOC");
> > > + printk("DEBUG_PAGEALLOC(%s)",
> > > + debug_pagealloc_enabled() ? "enabled" : "disabled");
> > > #endif
> >
> > I'd prefer if you change this to
> >
> > if (debug_pagealloc_enabled())
> > printk("DEBUG_PAGEALLOC");
> >
> > That way we can get rid of yet another ifdef. Having
> > "DEBUG_PAGEALLOC(disabled)" doesn't seem to be very helpful.
> >
>
> I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
> debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
> When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
> also enables stackinfo storing and poisoning and it's not guarded by
> debug_pagealloc_enabled().
>
> It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
> outside the scope of the debug_pagealloc=on kernel parameter, so
> DEBUG_PAGEALLOC(disabled) actually does mean something.
Hello, David.
I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
http://thread.gmane.org/gmane.linux.kernel.mm/144527
I found that there are more sites to fix but not so many.
We can do it.
Thanks.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 0:19 ` Joonsoo Kim
@ 2016-01-27 0:36 ` David Rientjes
-1 siblings, 0 replies; 34+ messages in thread
From: David Rientjes @ 2016-01-27 0:36 UTC (permalink / raw)
To: Joonsoo Kim
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On Wed, 27 Jan 2016, Joonsoo Kim wrote:
> > I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
> > debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
> > When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
> > also enables stackinfo storing and poisoning and it's not guarded by
> > debug_pagealloc_enabled().
> >
> > It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
> > outside the scope of the debug_pagealloc=on kernel parameter, so
> > DEBUG_PAGEALLOC(disabled) actually does mean something.
>
> Hello, David.
>
> I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
>
> http://thread.gmane.org/gmane.linux.kernel.mm/144527
>
> I found that there are more sites to fix but not so many.
> We can do it.
>
For the slab case, sure, this can be fixed, but there is other code that
uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is
indifferent to debug_pagealloc_enabled(). I find this in powerpc and
sparc arch code as well as generic vmalloc code.
If we can convert existing users that only check for
CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
agree that it is only enabled for debug_pagealloc=on, then this would seem
fine. However, I think we should at least consult with those users before
removing an artifact from the kernel log that could be useful in debugging
why a particular BUG() happened.
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 0:36 ` David Rientjes
0 siblings, 0 replies; 34+ messages in thread
From: David Rientjes @ 2016-01-27 0:36 UTC (permalink / raw)
To: Joonsoo Kim
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On Wed, 27 Jan 2016, Joonsoo Kim wrote:
> > I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
> > debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
> > When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
> > also enables stackinfo storing and poisoning and it's not guarded by
> > debug_pagealloc_enabled().
> >
> > It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
> > outside the scope of the debug_pagealloc=on kernel parameter, so
> > DEBUG_PAGEALLOC(disabled) actually does mean something.
>
> Hello, David.
>
> I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
>
> http://thread.gmane.org/gmane.linux.kernel.mm/144527
>
> I found that there are more sites to fix but not so many.
> We can do it.
>
For the slab case, sure, this can be fixed, but there is other code that
uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is
indifferent to debug_pagealloc_enabled(). I find this in powerpc and
sparc arch code as well as generic vmalloc code.
If we can convert existing users that only check for
CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
agree that it is only enabled for debug_pagealloc=on, then this would seem
fine. However, I think we should at least consult with those users before
removing an artifact from the kernel log that could be useful in debugging
why a particular BUG() happened.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 0:36 ` David Rientjes
@ 2016-01-27 0:59 ` Joonsoo Kim
-1 siblings, 0 replies; 34+ messages in thread
From: Joonsoo Kim @ 2016-01-27 0:59 UTC (permalink / raw)
To: David Rientjes
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
> On Wed, 27 Jan 2016, Joonsoo Kim wrote:
>
> > > I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
> > > debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
> > > When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
> > > also enables stackinfo storing and poisoning and it's not guarded by
> > > debug_pagealloc_enabled().
> > >
> > > It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
> > > outside the scope of the debug_pagealloc=on kernel parameter, so
> > > DEBUG_PAGEALLOC(disabled) actually does mean something.
> >
> > Hello, David.
> >
> > I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
> >
> > http://thread.gmane.org/gmane.linux.kernel.mm/144527
> >
> > I found that there are more sites to fix but not so many.
> > We can do it.
> >
>
> For the slab case, sure, this can be fixed, but there is other code that
> uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is
> indifferent to debug_pagealloc_enabled(). I find this in powerpc and
> sparc arch code as well as generic vmalloc code.
Yes, I also found it.
>
> If we can convert existing users that only check for
> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
> agree that it is only enabled for debug_pagealloc=on, then this would seem
> fine. However, I think we should at least consult with those users before
> removing an artifact from the kernel log that could be useful in debugging
> why a particular BUG() happened.
Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
be changed first. If Christian doesn't mind, I will try to fix above 3
things.
Thanks.
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 0:59 ` Joonsoo Kim
0 siblings, 0 replies; 34+ messages in thread
From: Joonsoo Kim @ 2016-01-27 0:59 UTC (permalink / raw)
To: David Rientjes
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
> On Wed, 27 Jan 2016, Joonsoo Kim wrote:
>
> > > I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
> > > debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
> > > When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
> > > also enables stackinfo storing and poisoning and it's not guarded by
> > > debug_pagealloc_enabled().
> > >
> > > It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
> > > outside the scope of the debug_pagealloc=on kernel parameter, so
> > > DEBUG_PAGEALLOC(disabled) actually does mean something.
> >
> > Hello, David.
> >
> > I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
> >
> > http://thread.gmane.org/gmane.linux.kernel.mm/144527
> >
> > I found that there are more sites to fix but not so many.
> > We can do it.
> >
>
> For the slab case, sure, this can be fixed, but there is other code that
> uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is
> indifferent to debug_pagealloc_enabled(). I find this in powerpc and
> sparc arch code as well as generic vmalloc code.
Yes, I also found it.
>
> If we can convert existing users that only check for
> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
> agree that it is only enabled for debug_pagealloc=on, then this would seem
> fine. However, I think we should at least consult with those users before
> removing an artifact from the kernel log that could be useful in debugging
> why a particular BUG() happened.
Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
be changed first. If Christian doesn't mind, I will try to fix above 3
things.
Thanks.
--
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 0:59 ` Joonsoo Kim
@ 2016-01-27 7:59 ` Christian Borntraeger
-1 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-27 7:59 UTC (permalink / raw)
To: Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
> On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
>> On Wed, 27 Jan 2016, Joonsoo Kim wrote:
>>
>>>> I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
>>>> debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
>>>> When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
>>>> also enables stackinfo storing and poisoning and it's not guarded by
>>>> debug_pagealloc_enabled().
>>>>
>>>> It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
>>>> outside the scope of the debug_pagealloc=on kernel parameter, so
>>>> DEBUG_PAGEALLOC(disabled) actually does mean something.
>>>
>>> Hello, David.
>>>
>>> I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
>>>
>>> http://thread.gmane.org/gmane.linux.kernel.mm/144527
>>>
>>> I found that there are more sites to fix but not so many.
>>> We can do it.
>>>
>>
>> For the slab case, sure, this can be fixed, but there is other code that
>> uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is
>> indifferent to debug_pagealloc_enabled(). I find this in powerpc and
>> sparc arch code as well as generic vmalloc code.
>
> Yes, I also found it.
>
>>
>> If we can convert existing users that only check for
>> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
>> agree that it is only enabled for debug_pagealloc=on, then this would seem
>> fine. However, I think we should at least consult with those users before
>> removing an artifact from the kernel log that could be useful in debugging
>> why a particular BUG() happened.
>
> Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
> be changed first. If Christian doesn't mind, I will try to fix above 3
> things.
Ok. So I will change this as Heiko and Thomas suggested for s390 and x86 and
resend these 3 patches. Feel free to work on the other areas.
Christian
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 7:59 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-27 7:59 UTC (permalink / raw)
To: Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
> On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
>> On Wed, 27 Jan 2016, Joonsoo Kim wrote:
>>
>>>> I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when
>>>> debug_pagealloc_enabled() is true, but that doesn't seem to be the case.
>>>> When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC
>>>> also enables stackinfo storing and poisoning and it's not guarded by
>>>> debug_pagealloc_enabled().
>>>>
>>>> It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality
>>>> outside the scope of the debug_pagealloc=on kernel parameter, so
>>>> DEBUG_PAGEALLOC(disabled) actually does mean something.
>>>
>>> Hello, David.
>>>
>>> I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset.
>>>
>>> http://thread.gmane.org/gmane.linux.kernel.mm/144527
>>>
>>> I found that there are more sites to fix but not so many.
>>> We can do it.
>>>
>>
>> For the slab case, sure, this can be fixed, but there is other code that
>> uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is
>> indifferent to debug_pagealloc_enabled(). I find this in powerpc and
>> sparc arch code as well as generic vmalloc code.
>
> Yes, I also found it.
>
>>
>> If we can convert existing users that only check for
>> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
>> agree that it is only enabled for debug_pagealloc=on, then this would seem
>> fine. However, I think we should at least consult with those users before
>> removing an artifact from the kernel log that could be useful in debugging
>> why a particular BUG() happened.
>
> Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
> be changed first. If Christian doesn't mind, I will try to fix above 3
> things.
Ok. So I will change this as Heiko and Thomas suggested for s390 and x86 and
resend these 3 patches. Feel free to work on the other areas.
Christian
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 0:59 ` Joonsoo Kim
@ 2016-01-27 12:41 ` Vlastimil Babka
-1 siblings, 0 replies; 34+ messages in thread
From: Vlastimil Babka @ 2016-01-27 12:41 UTC (permalink / raw)
To: Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
> On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
>>
>> If we can convert existing users that only check for
>> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
>> agree that it is only enabled for debug_pagealloc=on, then this would seem
>> fine. However, I think we should at least consult with those users before
>> removing an artifact from the kernel log that could be useful in debugging
>> why a particular BUG() happened.
>
> Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
> be changed first. If Christian doesn't mind, I will try to fix above 3
> things.
I think it might be worth also to convert debug_pagealloc_enabled() to be based
on static key, like I did for page_owner [1]. That should help make it possible
to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
without enabling it boot-time. I assume it's one of the goals here?
[1] http://www.spinics.net/lists/linux-mm/msg100795.html
> Thanks.
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 12:41 ` Vlastimil Babka
0 siblings, 0 replies; 34+ messages in thread
From: Vlastimil Babka @ 2016-01-27 12:41 UTC (permalink / raw)
To: Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, Christian Borntraeger, linux-kernel, akpm,
linux-mm, linux-arch, linux-s390, x86
On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
> On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
>>
>> If we can convert existing users that only check for
>> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
>> agree that it is only enabled for debug_pagealloc=on, then this would seem
>> fine. However, I think we should at least consult with those users before
>> removing an artifact from the kernel log that could be useful in debugging
>> why a particular BUG() happened.
>
> Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
> be changed first. If Christian doesn't mind, I will try to fix above 3
> things.
I think it might be worth also to convert debug_pagealloc_enabled() to be based
on static key, like I did for page_owner [1]. That should help make it possible
to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
without enabling it boot-time. I assume it's one of the goals here?
[1] http://www.spinics.net/lists/linux-mm/msg100795.html
> Thanks.
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 12:41 ` Vlastimil Babka
@ 2016-01-27 12:47 ` Christian Borntraeger
-1 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-27 12:47 UTC (permalink / raw)
To: Vlastimil Babka, Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
>> On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
>>>
>>> If we can convert existing users that only check for
>>> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
>>> agree that it is only enabled for debug_pagealloc=on, then this would seem
>>> fine. However, I think we should at least consult with those users before
>>> removing an artifact from the kernel log that could be useful in debugging
>>> why a particular BUG() happened.
>>
>> Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
>> be changed first. If Christian doesn't mind, I will try to fix above 3
>> things.
>
> I think it might be worth also to convert debug_pagealloc_enabled() to be based
> on static key, like I did for page_owner [1]. That should help make it possible
> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
> without enabling it boot-time. I assume it's one of the goals here?
We could do something like that but dump_stack and setup of the initial identity
mapping of the kernel as well as the initial page protection are not hot path
as far as I can tell. Any other places?
>
> [1] http://www.spinics.net/lists/linux-mm/msg100795.html
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 12:47 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-27 12:47 UTC (permalink / raw)
To: Vlastimil Babka, Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
>> On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote:
>>>
>>> If we can convert existing users that only check for
>>> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and
>>> agree that it is only enabled for debug_pagealloc=on, then this would seem
>>> fine. However, I think we should at least consult with those users before
>>> removing an artifact from the kernel log that could be useful in debugging
>>> why a particular BUG() happened.
>>
>> Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should
>> be changed first. If Christian doesn't mind, I will try to fix above 3
>> things.
>
> I think it might be worth also to convert debug_pagealloc_enabled() to be based
> on static key, like I did for page_owner [1]. That should help make it possible
> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
> without enabling it boot-time. I assume it's one of the goals here?
We could do something like that but dump_stack and setup of the initial identity
mapping of the kernel as well as the initial page protection are not hot path
as far as I can tell. Any other places?
>
> [1] http://www.spinics.net/lists/linux-mm/msg100795.html
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 12:47 ` Christian Borntraeger
@ 2016-01-27 13:03 ` Vlastimil Babka
-1 siblings, 0 replies; 34+ messages in thread
From: Vlastimil Babka @ 2016-01-27 13:03 UTC (permalink / raw)
To: Christian Borntraeger, Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 01:47 PM, Christian Borntraeger wrote:
> On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
>> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
>>
>> I think it might be worth also to convert debug_pagealloc_enabled() to be based
>> on static key, like I did for page_owner [1]. That should help make it possible
>> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
>> without enabling it boot-time. I assume it's one of the goals here?
>
> We could do something like that but dump_stack and setup of the initial identity
> mapping of the kernel as well as the initial page protection are not hot path
> as far as I can tell. Any other places?
Well, mostly kernel_map_pages() which is used in page allocation hotpaths.
>>
>> [1] http://www.spinics.net/lists/linux-mm/msg100795.html
>
>
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 13:03 ` Vlastimil Babka
0 siblings, 0 replies; 34+ messages in thread
From: Vlastimil Babka @ 2016-01-27 13:03 UTC (permalink / raw)
To: Christian Borntraeger, Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 01:47 PM, Christian Borntraeger wrote:
> On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
>> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
>>
>> I think it might be worth also to convert debug_pagealloc_enabled() to be based
>> on static key, like I did for page_owner [1]. That should help make it possible
>> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
>> without enabling it boot-time. I assume it's one of the goals here?
>
> We could do something like that but dump_stack and setup of the initial identity
> mapping of the kernel as well as the initial page protection are not hot path
> as far as I can tell. Any other places?
Well, mostly kernel_map_pages() which is used in page allocation hotpaths.
>>
>> [1] http://www.spinics.net/lists/linux-mm/msg100795.html
>
>
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 13:03 ` Vlastimil Babka
@ 2016-01-27 13:09 ` Christian Borntraeger
-1 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-27 13:09 UTC (permalink / raw)
To: Vlastimil Babka, Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 02:03 PM, Vlastimil Babka wrote:
> On 01/27/2016 01:47 PM, Christian Borntraeger wrote:
>> On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
>>> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
>>>
>>> I think it might be worth also to convert debug_pagealloc_enabled() to be based
>>> on static key, like I did for page_owner [1]. That should help make it possible
>>> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
>>> without enabling it boot-time. I assume it's one of the goals here?
>>
>> We could do something like that but dump_stack and setup of the initial identity
>> mapping of the kernel as well as the initial page protection are not hot path
>> as far as I can tell. Any other places?
>
> Well, mostly kernel_map_pages() which is used in page allocation hotpaths.
Right. So indeed, static_key would be a good thing, but certainly an addon patch.
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-27 13:09 ` Christian Borntraeger
0 siblings, 0 replies; 34+ messages in thread
From: Christian Borntraeger @ 2016-01-27 13:09 UTC (permalink / raw)
To: Vlastimil Babka, Joonsoo Kim, David Rientjes
Cc: Heiko Carstens, linux-kernel, akpm, linux-mm, linux-arch,
linux-s390, x86
On 01/27/2016 02:03 PM, Vlastimil Babka wrote:
> On 01/27/2016 01:47 PM, Christian Borntraeger wrote:
>> On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
>>> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
>>>
>>> I think it might be worth also to convert debug_pagealloc_enabled() to be based
>>> on static key, like I did for page_owner [1]. That should help make it possible
>>> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
>>> without enabling it boot-time. I assume it's one of the goals here?
>>
>> We could do something like that but dump_stack and setup of the initial identity
>> mapping of the kernel as well as the initial page protection are not hot path
>> as far as I can tell. Any other places?
>
> Well, mostly kernel_map_pages() which is used in page allocation hotpaths.
Right. So indeed, static_key would be a good thing, but certainly an addon patch.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
2016-01-27 13:03 ` Vlastimil Babka
@ 2016-01-28 4:25 ` Joonsoo Kim
-1 siblings, 0 replies; 34+ messages in thread
From: Joonsoo Kim @ 2016-01-28 4:25 UTC (permalink / raw)
To: Vlastimil Babka
Cc: Christian Borntraeger, David Rientjes, Heiko Carstens,
linux-kernel, akpm, linux-mm, linux-arch, linux-s390, x86
On Wed, Jan 27, 2016 at 02:03:36PM +0100, Vlastimil Babka wrote:
> On 01/27/2016 01:47 PM, Christian Borntraeger wrote:
> > On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
> >> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
> >>
> >> I think it might be worth also to convert debug_pagealloc_enabled() to be based
> >> on static key, like I did for page_owner [1]. That should help make it possible
> >> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
> >> without enabling it boot-time. I assume it's one of the goals here?
> >
> > We could do something like that but dump_stack and setup of the initial identity
> > mapping of the kernel as well as the initial page protection are not hot path
> > as far as I can tell. Any other places?
>
> Well, mostly kernel_map_pages() which is used in page allocation hotpaths.
We cannot just convert it because setup_arch() is called before
jump_label_init(). We can do it by introducing _early variant but
I'm not sure it's worth doing. I think that just make it unlikely
works well. Recently, I tested a micro benchmark on slab alloc/free
on CONFIG_SLUB with applying static branch for debug option which
currently is using unlikely branch and can't find any noticeble
performance difference.
Thanks.
^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting
@ 2016-01-28 4:25 ` Joonsoo Kim
0 siblings, 0 replies; 34+ messages in thread
From: Joonsoo Kim @ 2016-01-28 4:25 UTC (permalink / raw)
To: Vlastimil Babka
Cc: Christian Borntraeger, David Rientjes, Heiko Carstens,
linux-kernel, akpm, linux-mm, linux-arch, linux-s390, x86
On Wed, Jan 27, 2016 at 02:03:36PM +0100, Vlastimil Babka wrote:
> On 01/27/2016 01:47 PM, Christian Borntraeger wrote:
> > On 01/27/2016 01:41 PM, Vlastimil Babka wrote:
> >> On 01/27/2016 01:59 AM, Joonsoo Kim wrote:
> >>
> >> I think it might be worth also to convert debug_pagealloc_enabled() to be based
> >> on static key, like I did for page_owner [1]. That should help make it possible
> >> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC
> >> without enabling it boot-time. I assume it's one of the goals here?
> >
> > We could do something like that but dump_stack and setup of the initial identity
> > mapping of the kernel as well as the initial page protection are not hot path
> > as far as I can tell. Any other places?
>
> Well, mostly kernel_map_pages() which is used in page allocation hotpaths.
We cannot just convert it because setup_arch() is called before
jump_label_init(). We can do it by introducing _early variant but
I'm not sure it's worth doing. I think that just make it unlikely
works well. Recently, I tested a micro benchmark on slab alloc/free
on CONFIG_SLUB with applying static branch for debug option which
currently is using unlikely branch and can't find any noticeble
performance difference.
Thanks.
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^ permalink raw reply [flat|nested] 34+ messages in thread
end of thread, other threads:[~2016-01-28 4:30 UTC | newest]
Thread overview: 34+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-01-26 9:18 [PATCH/RFC 0/3] Optimize CONFIG_DEBUG_PAGEALLOC Christian Borntraeger
2016-01-26 9:18 ` Christian Borntraeger
2016-01-26 9:18 ` [PATCH/RFC 1/3] mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC Christian Borntraeger
2016-01-26 9:18 ` Christian Borntraeger
2016-01-26 23:23 ` David Rientjes
2016-01-26 23:23 ` David Rientjes
2016-01-26 9:18 ` [PATCH/RFC 2/3] x86: query dynamic DEBUG_PAGEALLOC setting Christian Borntraeger
2016-01-26 9:18 ` Christian Borntraeger
2016-01-26 9:18 ` [PATCH/RFC 3/3] s390: " Christian Borntraeger
2016-01-26 9:18 ` Christian Borntraeger
2016-01-26 18:19 ` Heiko Carstens
2016-01-26 18:19 ` Heiko Carstens
2016-01-26 20:38 ` Thomas Gleixner
2016-01-26 20:38 ` Thomas Gleixner
2016-01-26 23:29 ` David Rientjes
2016-01-26 23:29 ` David Rientjes
2016-01-27 0:19 ` Joonsoo Kim
2016-01-27 0:19 ` Joonsoo Kim
2016-01-27 0:36 ` David Rientjes
2016-01-27 0:36 ` David Rientjes
2016-01-27 0:59 ` Joonsoo Kim
2016-01-27 0:59 ` Joonsoo Kim
2016-01-27 7:59 ` Christian Borntraeger
2016-01-27 7:59 ` Christian Borntraeger
2016-01-27 12:41 ` Vlastimil Babka
2016-01-27 12:41 ` Vlastimil Babka
2016-01-27 12:47 ` Christian Borntraeger
2016-01-27 12:47 ` Christian Borntraeger
2016-01-27 13:03 ` Vlastimil Babka
2016-01-27 13:03 ` Vlastimil Babka
2016-01-27 13:09 ` Christian Borntraeger
2016-01-27 13:09 ` Christian Borntraeger
2016-01-28 4:25 ` Joonsoo Kim
2016-01-28 4:25 ` Joonsoo Kim
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