[PATCH] Allow memory hotplug and hibernation in the same kernel

[PATCH] Allow memory hotplug and hibernation in the same kernel

[Andi Kleen]

Allow memory hotplug and hibernation in the same kernel

Memory hotplug and hibernation was excluded in Kconfig. This is obviously
a problem for distribution kernels who want to support both in the same
image.

After some discussions with Rafael and others the only problem is 
with parallel memory hotadd or removal while a hibernation operation
is in process. It was also working for s390 before.

This patch removes the Kconfig level exclusion, and simply
makes the memory add / remove functions grab the pm_mutex
to exclude against hibernation.

This is a 2.6.32 candidate.

Cc: gerald.schaefer@de.ibm.com
Cc: rjw@sisk.pl

Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
 include/linux/suspend.h |   21 +++++++++++++++++++--
 mm/Kconfig              |    5 +----
 mm/memory_hotplug.c     |   21 +++++++++++++++++----
 3 files changed, 37 insertions(+), 10 deletions(-)

Index: linux-2.6.32-rc6-ak/include/linux/suspend.h
===================================================================
--- linux-2.6.32-rc6-ak.orig/include/linux/suspend.h
+++ linux-2.6.32-rc6-ak/include/linux/suspend.h
@@ -301,6 +301,8 @@ static inline int unregister_pm_notifier
 #define pm_notifier(fn, pri)	do { (void)(fn); } while (0)
 #endif /* !CONFIG_PM_SLEEP */
 
+extern struct mutex pm_mutex;
+
 #ifndef CONFIG_HIBERNATION
 static inline void register_nosave_region(unsigned long b, unsigned long e)
 {
@@ -308,8 +310,23 @@ static inline void register_nosave_regio
 static inline void register_nosave_region_late(unsigned long b, unsigned long e)
 {
 }
-#endif
 
-extern struct mutex pm_mutex;
+static inline void lock_hibernation(void) {}
+static inline void unlock_hibernation(void) {}
+
+#else
+
+/* Let some subsystems like memory hotadd exclude hibernation */
+
+static inline void lock_hibernation(void)
+{
+	mutex_lock(&pm_mutex);
+}
+
+static inline void unlock_hibernation(void)
+{
+	mutex_unlock(&pm_mutex);
+}
+#endif
 
 #endif /* _LINUX_SUSPEND_H */
Index: linux-2.6.32-rc6-ak/mm/Kconfig
===================================================================
--- linux-2.6.32-rc6-ak.orig/mm/Kconfig
+++ linux-2.6.32-rc6-ak/mm/Kconfig
@@ -128,12 +128,9 @@ config SPARSEMEM_VMEMMAP
 config MEMORY_HOTPLUG
 	bool "Allow for memory hot-add"
 	depends on SPARSEMEM || X86_64_ACPI_NUMA
-	depends on HOTPLUG && !(HIBERNATION && !S390) && ARCH_ENABLE_MEMORY_HOTPLUG
+	depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
 	depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
 
-comment "Memory hotplug is currently incompatible with Software Suspend"
-	depends on SPARSEMEM && HOTPLUG && HIBERNATION && !S390
-
 config MEMORY_HOTPLUG_SPARSE
 	def_bool y
 	depends on SPARSEMEM && MEMORY_HOTPLUG
Index: linux-2.6.32-rc6-ak/mm/memory_hotplug.c
===================================================================
--- linux-2.6.32-rc6-ak.orig/mm/memory_hotplug.c
+++ linux-2.6.32-rc6-ak/mm/memory_hotplug.c
@@ -26,6 +26,7 @@
 #include <linux/migrate.h>
 #include <linux/page-isolation.h>
 #include <linux/pfn.h>
+#include <linux/suspend.h>
 
 #include <asm/tlbflush.h>
 
@@ -484,14 +485,18 @@ int __ref add_memory(int nid, u64 start,
 	struct resource *res;
 	int ret;
 
+	lock_hibernation();
+
 	res = register_memory_resource(start, size);
+	ret = -EEXIST;
 	if (!res)
-		return -EEXIST;
+		goto out;
 
 	if (!node_online(nid)) {
 		pgdat = hotadd_new_pgdat(nid, start);
+		ret = -ENOMEM;
 		if (!pgdat)
-			return -ENOMEM;
+			goto out;
 		new_pgdat = 1;
 	}
 
@@ -514,7 +519,8 @@ int __ref add_memory(int nid, u64 start,
 		BUG_ON(ret);
 	}
 
-	return ret;
+	goto out;
+
 error:
 	/* rollback pgdat allocation and others */
 	if (new_pgdat)
@@ -522,6 +528,8 @@ error:
 	if (res)
 		release_memory_resource(res);
 
+out:
+	unlock_hibernation();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(add_memory);
@@ -758,6 +766,8 @@ int offline_pages(unsigned long start_pf
 	if (!test_pages_in_a_zone(start_pfn, end_pfn))
 		return -EINVAL;
 
+	lock_hibernation();
+
 	zone = page_zone(pfn_to_page(start_pfn));
 	node = zone_to_nid(zone);
 	nr_pages = end_pfn - start_pfn;
@@ -765,7 +775,7 @@ int offline_pages(unsigned long start_pf
 	/* set above range as isolated */
 	ret = start_isolate_page_range(start_pfn, end_pfn);
 	if (ret)
-		return ret;
+		goto out;
 
 	arg.start_pfn = start_pfn;
 	arg.nr_pages = nr_pages;
@@ -843,6 +853,7 @@ repeat:
 	writeback_set_ratelimit();
 
 	memory_notify(MEM_OFFLINE, &arg);
+	unlock_hibernation();
 	return 0;
 
 failed_removal:
@@ -852,6 +863,8 @@ failed_removal:
 	/* pushback to free area */
 	undo_isolate_page_range(start_pfn, end_pfn);
 
+out:
+	unlock_hibernation();
 	return ret;
 }
 

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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[KOSAKI Motohiro]

(cc to goto-san)

> Allow memory hotplug and hibernation in the same kernel
> 
> Memory hotplug and hibernation was excluded in Kconfig. This is obviously
> a problem for distribution kernels who want to support both in the same
> image.

Sure.

This exclusion is nearly meaningless. if anybody remove cpu, memory and/or
various peripheral from hibernated machine. the system might not resume.
it's obvious. memory is not special.

Documentation/power/swsusp.txt explicitly said

	 * BIG FAT WARNING *********************************************************
	 *
	 * If you touch anything on disk between suspend and resume...
	 *                              ...kiss your data goodbye.


I like this patch.


> 
> After some discussions with Rafael and others the only problem is 
> with parallel memory hotadd or removal while a hibernation operation
> is in process. It was also working for s390 before.
> 
> This patch removes the Kconfig level exclusion, and simply
> makes the memory add / remove functions grab the pm_mutex
> to exclude against hibernation.
> 
> This is a 2.6.32 candidate.
> 
> Cc: gerald.schaefer@de.ibm.com
> Cc: rjw@sisk.pl
> 
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> 
> ---
>  include/linux/suspend.h |   21 +++++++++++++++++++--
>  mm/Kconfig              |    5 +----
>  mm/memory_hotplug.c     |   21 +++++++++++++++++----
>  3 files changed, 37 insertions(+), 10 deletions(-)
> 
> Index: linux-2.6.32-rc6-ak/include/linux/suspend.h
> ===================================================================
> --- linux-2.6.32-rc6-ak.orig/include/linux/suspend.h
> +++ linux-2.6.32-rc6-ak/include/linux/suspend.h
> @@ -301,6 +301,8 @@ static inline int unregister_pm_notifier
>  #define pm_notifier(fn, pri)	do { (void)(fn); } while (0)
>  #endif /* !CONFIG_PM_SLEEP */
>  
> +extern struct mutex pm_mutex;
> +
>  #ifndef CONFIG_HIBERNATION
>  static inline void register_nosave_region(unsigned long b, unsigned long e)
>  {
> @@ -308,8 +310,23 @@ static inline void register_nosave_regio
>  static inline void register_nosave_region_late(unsigned long b, unsigned long e)
>  {
>  }
> -#endif
>  
> -extern struct mutex pm_mutex;
> +static inline void lock_hibernation(void) {}
> +static inline void unlock_hibernation(void) {}
> +
> +#else
> +
> +/* Let some subsystems like memory hotadd exclude hibernation */
> +
> +static inline void lock_hibernation(void)
> +{
> +	mutex_lock(&pm_mutex);
> +}
> +
> +static inline void unlock_hibernation(void)
> +{
> +	mutex_unlock(&pm_mutex);
> +}
> +#endif
>  
>  #endif /* _LINUX_SUSPEND_H */
> Index: linux-2.6.32-rc6-ak/mm/Kconfig
> ===================================================================
> --- linux-2.6.32-rc6-ak.orig/mm/Kconfig
> +++ linux-2.6.32-rc6-ak/mm/Kconfig
> @@ -128,12 +128,9 @@ config SPARSEMEM_VMEMMAP
>  config MEMORY_HOTPLUG
>  	bool "Allow for memory hot-add"
>  	depends on SPARSEMEM || X86_64_ACPI_NUMA
> -	depends on HOTPLUG && !(HIBERNATION && !S390) && ARCH_ENABLE_MEMORY_HOTPLUG
> +	depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
>  	depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
>  
> -comment "Memory hotplug is currently incompatible with Software Suspend"
> -	depends on SPARSEMEM && HOTPLUG && HIBERNATION && !S390
> -
>  config MEMORY_HOTPLUG_SPARSE
>  	def_bool y
>  	depends on SPARSEMEM && MEMORY_HOTPLUG
> Index: linux-2.6.32-rc6-ak/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.32-rc6-ak.orig/mm/memory_hotplug.c
> +++ linux-2.6.32-rc6-ak/mm/memory_hotplug.c
> @@ -26,6 +26,7 @@
>  #include <linux/migrate.h>
>  #include <linux/page-isolation.h>
>  #include <linux/pfn.h>
> +#include <linux/suspend.h>
>  
>  #include <asm/tlbflush.h>
>  
> @@ -484,14 +485,18 @@ int __ref add_memory(int nid, u64 start,
>  	struct resource *res;
>  	int ret;
>  
> +	lock_hibernation();
> +
>  	res = register_memory_resource(start, size);
> +	ret = -EEXIST;
>  	if (!res)
> -		return -EEXIST;
> +		goto out;
>  
>  	if (!node_online(nid)) {
>  		pgdat = hotadd_new_pgdat(nid, start);
> +		ret = -ENOMEM;
>  		if (!pgdat)
> -			return -ENOMEM;
> +			goto out;
>  		new_pgdat = 1;
>  	}
>  
> @@ -514,7 +519,8 @@ int __ref add_memory(int nid, u64 start,
>  		BUG_ON(ret);
>  	}
>  
> -	return ret;
> +	goto out;
> +
>  error:
>  	/* rollback pgdat allocation and others */
>  	if (new_pgdat)
> @@ -522,6 +528,8 @@ error:
>  	if (res)
>  		release_memory_resource(res);
>  
> +out:
> +	unlock_hibernation();
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(add_memory);
> @@ -758,6 +766,8 @@ int offline_pages(unsigned long start_pf
>  	if (!test_pages_in_a_zone(start_pfn, end_pfn))
>  		return -EINVAL;
>  
> +	lock_hibernation();
> +
>  	zone = page_zone(pfn_to_page(start_pfn));
>  	node = zone_to_nid(zone);
>  	nr_pages = end_pfn - start_pfn;
> @@ -765,7 +775,7 @@ int offline_pages(unsigned long start_pf
>  	/* set above range as isolated */
>  	ret = start_isolate_page_range(start_pfn, end_pfn);
>  	if (ret)
> -		return ret;
> +		goto out;
>  
>  	arg.start_pfn = start_pfn;
>  	arg.nr_pages = nr_pages;
> @@ -843,6 +853,7 @@ repeat:
>  	writeback_set_ratelimit();
>  
>  	memory_notify(MEM_OFFLINE, &arg);
> +	unlock_hibernation();
>  	return 0;
>  
>  failed_removal:
> @@ -852,6 +863,8 @@ failed_removal:
>  	/* pushback to free area */
>  	undo_isolate_page_range(start_pfn, end_pfn);
>  
> +out:
> +	unlock_hibernation();
>  	return ret;
>  }
>  
> 
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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[KOSAKI Motohiro]

> (cc to goto-san)
> 
> > Allow memory hotplug and hibernation in the same kernel
> > 
> > Memory hotplug and hibernation was excluded in Kconfig. This is obviously
> > a problem for distribution kernels who want to support both in the same
> > image.
> 
> Sure.
> 
> This exclusion is nearly meaningless. if anybody remove cpu, memory and/or
> various peripheral from hibernated machine. the system might not resume.
> it's obvious. memory is not special.
> 
> Documentation/power/swsusp.txt explicitly said
> 
> 	 * BIG FAT WARNING *********************************************************
> 	 *
> 	 * If you touch anything on disk between suspend and resume...
> 	 *                              ...kiss your data goodbye.
> 
> 
> I like this patch.
> 
> 
> > 
> > After some discussions with Rafael and others the only problem is 
> > with parallel memory hotadd or removal while a hibernation operation
> > is in process. It was also working for s390 before.
> > 
> > This patch removes the Kconfig level exclusion, and simply
> > makes the memory add / remove functions grab the pm_mutex
> > to exclude against hibernation.
> > 
> > This is a 2.6.32 candidate.

2.6.32?




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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Andi Kleen]

> > > This is a 2.6.32 candidate.
> 
> 2.6.32?

Well stable at least. But it's simple enough and fixes an obvious
problem and in fact a regression (old kernels didn't exclude memory hotadd
and hibernation), so it could be even a 2.6.32.0 candidate.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.

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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Andi Kleen]

On Fri, Nov 13, 2009 at 08:13:23PM +0900, KOSAKI Motohiro wrote:
> (cc to goto-san)
> 
> > Allow memory hotplug and hibernation in the same kernel
> > 
> > Memory hotplug and hibernation was excluded in Kconfig. This is obviously
> > a problem for distribution kernels who want to support both in the same
> > image.
> 
> Sure.
> 
> This exclusion is nearly meaningless. if anybody remove cpu, memory and/or
> various peripheral from hibernated machine. the system might not resume.
> it's obvious. memory is not special.


The main motivation for the patch is really just to allow both in the 
same kernel (so the Kconfig change). The actual exclusion is 
not really very interesting as you point out.

Otherwise memory hotadd is not usable in universal kernel that
runs on laptops too.

-Andi

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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Rafael J. Wysocki]

On Friday 13 November 2009, Andi Kleen wrote:
> Allow memory hotplug and hibernation in the same kernel
> 
> Memory hotplug and hibernation was excluded in Kconfig. This is obviously
> a problem for distribution kernels who want to support both in the same
> image.
> 
> After some discussions with Rafael and others the only problem is 
> with parallel memory hotadd or removal while a hibernation operation
> is in process. It was also working for s390 before.
> 
> This patch removes the Kconfig level exclusion, and simply
> makes the memory add / remove functions grab the pm_mutex
> to exclude against hibernation.
> 
> This is a 2.6.32 candidate.
> 
> Cc: gerald.schaefer@de.ibm.com
> Cc: rjw@sisk.pl
> 
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> 
> ---
>  include/linux/suspend.h |   21 +++++++++++++++++++--
>  mm/Kconfig              |    5 +----
>  mm/memory_hotplug.c     |   21 +++++++++++++++++----
>  3 files changed, 37 insertions(+), 10 deletions(-)
> 
> Index: linux-2.6.32-rc6-ak/include/linux/suspend.h
> ===================================================================
> --- linux-2.6.32-rc6-ak.orig/include/linux/suspend.h
> +++ linux-2.6.32-rc6-ak/include/linux/suspend.h
> @@ -301,6 +301,8 @@ static inline int unregister_pm_notifier
>  #define pm_notifier(fn, pri)	do { (void)(fn); } while (0)
>  #endif /* !CONFIG_PM_SLEEP */
>  
> +extern struct mutex pm_mutex;
> +
>  #ifndef CONFIG_HIBERNATION
>  static inline void register_nosave_region(unsigned long b, unsigned long e)
>  {
> @@ -308,8 +310,23 @@ static inline void register_nosave_regio
>  static inline void register_nosave_region_late(unsigned long b, unsigned long e)
>  {
>  }
> -#endif
>  
> -extern struct mutex pm_mutex;
> +static inline void lock_hibernation(void) {}
> +static inline void unlock_hibernation(void) {}
> +
> +#else
> +
> +/* Let some subsystems like memory hotadd exclude hibernation */
> +
> +static inline void lock_hibernation(void)
> +{
> +	mutex_lock(&pm_mutex);
> +}
> +
> +static inline void unlock_hibernation(void)
> +{
> +	mutex_unlock(&pm_mutex);
> +}

This also is going to affect suspend to RAM, which kind of makes sense BTW,
so I'd not put it under the #ifdef.  Also, the names should reflect the fact
that suspend is affected too.  What about block|unblock_system_sleep()?

> +#endif
>  
>  #endif /* _LINUX_SUSPEND_H */

The rest of the patch is fine by me.

Thanks,
Rafael

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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Andi Kleen]

> This also is going to affect suspend to RAM, which kind of makes sense BTW,
> so I'd not put it under the #ifdef.  Also, the names should reflect the fact
> that suspend is affected too.  What about block|unblock_system_sleep()?

Here's a updated version with that rename.

-Andi

---

Allow memory hotplug and hibernation in the same kernel v2

Memory hotplug and hibernation was excluded in Kconfig. This is obviously
a problem for distribution kernels who want to support both in the same
image.

After some discussions with Rafael and others the only problem is 
with parallel memory hotadd or removal while a hibernation operation
is in process. It was also working for s390 before.

This patch removes the Kconfig level exclusion, and simply
makes the memory add / remove functions grab the pm_mutex
to exclude against hibernation.

This is a 2.6.32 candidate.

v2: Rename lock_hibernation to lock_system_sleep

Cc: gerald.schaefer@de.ibm.com
Cc: rjw@sisk.pl

Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
 include/linux/suspend.h |   21 +++++++++++++++++++--
 mm/Kconfig              |    5 +----
 mm/memory_hotplug.c     |   21 +++++++++++++++++----
 3 files changed, 37 insertions(+), 10 deletions(-)

Index: linux-2.6.32-rc6-ak/include/linux/suspend.h
===================================================================
--- linux-2.6.32-rc6-ak.orig/include/linux/suspend.h
+++ linux-2.6.32-rc6-ak/include/linux/suspend.h
@@ -301,6 +301,8 @@ static inline int unregister_pm_notifier
 #define pm_notifier(fn, pri)	do { (void)(fn); } while (0)
 #endif /* !CONFIG_PM_SLEEP */
 
+extern struct mutex pm_mutex;
+
 #ifndef CONFIG_HIBERNATION
 static inline void register_nosave_region(unsigned long b, unsigned long e)
 {
@@ -308,8 +310,23 @@ static inline void register_nosave_regio
 static inline void register_nosave_region_late(unsigned long b, unsigned long e)
 {
 }
-#endif
 
-extern struct mutex pm_mutex;
+static inline void lock_system_sleep(void) {}
+static inline void unlock_system_sleep(void) {}
+
+#else
+
+/* Let some subsystems like memory hotadd exclude hibernation */
+
+static inline void lock_system_sleep(void)
+{
+	mutex_lock(&pm_mutex);
+}
+
+static inline void unlock_system_sleep(void)
+{
+	mutex_unlock(&pm_mutex);
+}
+#endif
 
 #endif /* _LINUX_SUSPEND_H */
Index: linux-2.6.32-rc6-ak/mm/Kconfig
===================================================================
--- linux-2.6.32-rc6-ak.orig/mm/Kconfig
+++ linux-2.6.32-rc6-ak/mm/Kconfig
@@ -128,12 +128,9 @@ config SPARSEMEM_VMEMMAP
 config MEMORY_HOTPLUG
 	bool "Allow for memory hot-add"
 	depends on SPARSEMEM || X86_64_ACPI_NUMA
-	depends on HOTPLUG && !(HIBERNATION && !S390) && ARCH_ENABLE_MEMORY_HOTPLUG
+	depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
 	depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
 
-comment "Memory hotplug is currently incompatible with Software Suspend"
-	depends on SPARSEMEM && HOTPLUG && HIBERNATION && !S390
-
 config MEMORY_HOTPLUG_SPARSE
 	def_bool y
 	depends on SPARSEMEM && MEMORY_HOTPLUG
Index: linux-2.6.32-rc6-ak/mm/memory_hotplug.c
===================================================================
--- linux-2.6.32-rc6-ak.orig/mm/memory_hotplug.c
+++ linux-2.6.32-rc6-ak/mm/memory_hotplug.c
@@ -26,6 +26,7 @@
 #include <linux/migrate.h>
 #include <linux/page-isolation.h>
 #include <linux/pfn.h>
+#include <linux/suspend.h>
 
 #include <asm/tlbflush.h>
 
@@ -484,14 +485,18 @@ int __ref add_memory(int nid, u64 start,
 	struct resource *res;
 	int ret;
 
+	lock_system_sleep();
+
 	res = register_memory_resource(start, size);
+	ret = -EEXIST;
 	if (!res)
-		return -EEXIST;
+		goto out;
 
 	if (!node_online(nid)) {
 		pgdat = hotadd_new_pgdat(nid, start);
+		ret = -ENOMEM;
 		if (!pgdat)
-			return -ENOMEM;
+			goto out;
 		new_pgdat = 1;
 	}
 
@@ -514,7 +519,8 @@ int __ref add_memory(int nid, u64 start,
 		BUG_ON(ret);
 	}
 
-	return ret;
+	goto out;
+
 error:
 	/* rollback pgdat allocation and others */
 	if (new_pgdat)
@@ -522,6 +528,8 @@ error:
 	if (res)
 		release_memory_resource(res);
 
+out:
+	unlock_system_sleep();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(add_memory);
@@ -758,6 +766,8 @@ int offline_pages(unsigned long start_pf
 	if (!test_pages_in_a_zone(start_pfn, end_pfn))
 		return -EINVAL;
 
+	lock_system_sleep();
+
 	zone = page_zone(pfn_to_page(start_pfn));
 	node = zone_to_nid(zone);
 	nr_pages = end_pfn - start_pfn;
@@ -765,7 +775,7 @@ int offline_pages(unsigned long start_pf
 	/* set above range as isolated */
 	ret = start_isolate_page_range(start_pfn, end_pfn);
 	if (ret)
-		return ret;
+		goto out;
 
 	arg.start_pfn = start_pfn;
 	arg.nr_pages = nr_pages;
@@ -843,6 +853,7 @@ repeat:
 	writeback_set_ratelimit();
 
 	memory_notify(MEM_OFFLINE, &arg);
+	unlock_system_sleep();
 	return 0;
 
 failed_removal:
@@ -852,6 +863,8 @@ failed_removal:
 	/* pushback to free area */
 	undo_isolate_page_range(start_pfn, end_pfn);
 
+out:
+	unlock_system_sleep();
 	return ret;
 }
 

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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Rafael J. Wysocki]

On Saturday 14 November 2009, Andi Kleen wrote:
> > This also is going to affect suspend to RAM, which kind of makes sense BTW,
> > so I'd not put it under the #ifdef.  Also, the names should reflect the fact
> > that suspend is affected too.  What about block|unblock_system_sleep()?
> 
> Here's a updated version with that rename.
> 
> -Andi
> 
> ---
> 
> Allow memory hotplug and hibernation in the same kernel v2
> 
> Memory hotplug and hibernation was excluded in Kconfig. This is obviously
> a problem for distribution kernels who want to support both in the same
> image.
> 
> After some discussions with Rafael and others the only problem is 
> with parallel memory hotadd or removal while a hibernation operation
> is in process. It was also working for s390 before.
> 
> This patch removes the Kconfig level exclusion, and simply
> makes the memory add / remove functions grab the pm_mutex
> to exclude against hibernation.
> 
> This is a 2.6.32 candidate.
> 
> v2: Rename lock_hibernation to lock_system_sleep
> 
> Cc: gerald.schaefer@de.ibm.com
> Cc: rjw@sisk.pl

Acked-by: Rafael J. Wysocki <rjw@sisk.pl>

Thanks!

> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> 
> ---
>  include/linux/suspend.h |   21 +++++++++++++++++++--
>  mm/Kconfig              |    5 +----
>  mm/memory_hotplug.c     |   21 +++++++++++++++++----
>  3 files changed, 37 insertions(+), 10 deletions(-)
> 
> Index: linux-2.6.32-rc6-ak/include/linux/suspend.h
> ===================================================================
> --- linux-2.6.32-rc6-ak.orig/include/linux/suspend.h
> +++ linux-2.6.32-rc6-ak/include/linux/suspend.h
> @@ -301,6 +301,8 @@ static inline int unregister_pm_notifier
>  #define pm_notifier(fn, pri)	do { (void)(fn); } while (0)
>  #endif /* !CONFIG_PM_SLEEP */
>  
> +extern struct mutex pm_mutex;
> +
>  #ifndef CONFIG_HIBERNATION
>  static inline void register_nosave_region(unsigned long b, unsigned long e)
>  {
> @@ -308,8 +310,23 @@ static inline void register_nosave_regio
>  static inline void register_nosave_region_late(unsigned long b, unsigned long e)
>  {
>  }
> -#endif
>  
> -extern struct mutex pm_mutex;
> +static inline void lock_system_sleep(void) {}
> +static inline void unlock_system_sleep(void) {}
> +
> +#else
> +
> +/* Let some subsystems like memory hotadd exclude hibernation */
> +
> +static inline void lock_system_sleep(void)
> +{
> +	mutex_lock(&pm_mutex);
> +}
> +
> +static inline void unlock_system_sleep(void)
> +{
> +	mutex_unlock(&pm_mutex);
> +}
> +#endif
>  
>  #endif /* _LINUX_SUSPEND_H */
> Index: linux-2.6.32-rc6-ak/mm/Kconfig
> ===================================================================
> --- linux-2.6.32-rc6-ak.orig/mm/Kconfig
> +++ linux-2.6.32-rc6-ak/mm/Kconfig
> @@ -128,12 +128,9 @@ config SPARSEMEM_VMEMMAP
>  config MEMORY_HOTPLUG
>  	bool "Allow for memory hot-add"
>  	depends on SPARSEMEM || X86_64_ACPI_NUMA
> -	depends on HOTPLUG && !(HIBERNATION && !S390) && ARCH_ENABLE_MEMORY_HOTPLUG
> +	depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
>  	depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
>  
> -comment "Memory hotplug is currently incompatible with Software Suspend"
> -	depends on SPARSEMEM && HOTPLUG && HIBERNATION && !S390
> -
>  config MEMORY_HOTPLUG_SPARSE
>  	def_bool y
>  	depends on SPARSEMEM && MEMORY_HOTPLUG
> Index: linux-2.6.32-rc6-ak/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.32-rc6-ak.orig/mm/memory_hotplug.c
> +++ linux-2.6.32-rc6-ak/mm/memory_hotplug.c
> @@ -26,6 +26,7 @@
>  #include <linux/migrate.h>
>  #include <linux/page-isolation.h>
>  #include <linux/pfn.h>
> +#include <linux/suspend.h>
>  
>  #include <asm/tlbflush.h>
>  
> @@ -484,14 +485,18 @@ int __ref add_memory(int nid, u64 start,
>  	struct resource *res;
>  	int ret;
>  
> +	lock_system_sleep();
> +
>  	res = register_memory_resource(start, size);
> +	ret = -EEXIST;
>  	if (!res)
> -		return -EEXIST;
> +		goto out;
>  
>  	if (!node_online(nid)) {
>  		pgdat = hotadd_new_pgdat(nid, start);
> +		ret = -ENOMEM;
>  		if (!pgdat)
> -			return -ENOMEM;
> +			goto out;
>  		new_pgdat = 1;
>  	}
>  
> @@ -514,7 +519,8 @@ int __ref add_memory(int nid, u64 start,
>  		BUG_ON(ret);
>  	}
>  
> -	return ret;
> +	goto out;
> +
>  error:
>  	/* rollback pgdat allocation and others */
>  	if (new_pgdat)
> @@ -522,6 +528,8 @@ error:
>  	if (res)
>  		release_memory_resource(res);
>  
> +out:
> +	unlock_system_sleep();
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(add_memory);
> @@ -758,6 +766,8 @@ int offline_pages(unsigned long start_pf
>  	if (!test_pages_in_a_zone(start_pfn, end_pfn))
>  		return -EINVAL;
>  
> +	lock_system_sleep();
> +
>  	zone = page_zone(pfn_to_page(start_pfn));
>  	node = zone_to_nid(zone);
>  	nr_pages = end_pfn - start_pfn;
> @@ -765,7 +775,7 @@ int offline_pages(unsigned long start_pf
>  	/* set above range as isolated */
>  	ret = start_isolate_page_range(start_pfn, end_pfn);
>  	if (ret)
> -		return ret;
> +		goto out;
>  
>  	arg.start_pfn = start_pfn;
>  	arg.nr_pages = nr_pages;
> @@ -843,6 +853,7 @@ repeat:
>  	writeback_set_ratelimit();
>  
>  	memory_notify(MEM_OFFLINE, &arg);
> +	unlock_system_sleep();
>  	return 0;
>  
>  failed_removal:
> @@ -852,6 +863,8 @@ failed_removal:
>  	/* pushback to free area */
>  	undo_isolate_page_range(start_pfn, end_pfn);
>  
> +out:
> +	unlock_system_sleep();
>  	return ret;
>  }
>  
> 
> 

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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Andrew Morton]

On Fri, 13 Nov 2009 11:59:44 +0100
Andi Kleen <andi@firstfloor.org> wrote:

> Allow memory hotplug and hibernation in the same kernel
> 
> Memory hotplug and hibernation was excluded in Kconfig. This is obviously
> a problem for distribution kernels who want to support both in the same
> image.
> 
> After some discussions with Rafael and others the only problem is 
> with parallel memory hotadd or removal while a hibernation operation
> is in process. It was also working for s390 before.
> 
> This patch removes the Kconfig level exclusion, and simply
> makes the memory add / remove functions grab the pm_mutex
> to exclude against hibernation.
> 
> ...
>
> +extern struct mutex pm_mutex;

Am a bit worried by the new mutex.

>  #ifndef CONFIG_HIBERNATION
>  static inline void register_nosave_region(unsigned long b, unsigned long e)
>  {
> @@ -308,8 +310,23 @@ static inline void register_nosave_regio
>  static inline void register_nosave_region_late(unsigned long b, unsigned long e)
>  {
>  }
> -#endif
>  
> -extern struct mutex pm_mutex;
> +static inline void lock_hibernation(void) {}
> +static inline void unlock_hibernation(void) {}
> +
> +#else
> +
> +/* Let some subsystems like memory hotadd exclude hibernation */
> +
> +static inline void lock_hibernation(void)
> +{
> +	mutex_lock(&pm_mutex);
> +}
> +
> +static inline void unlock_hibernation(void)
> +{
> +	mutex_unlock(&pm_mutex);
> +}
> +#endif

Has this been carefully reviewed and lockdep-tested to ensure that we
didn't introduce any ab/ba nasties?


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Re: [PATCH] Allow memory hotplug and hibernation in the same kernel

[Andi Kleen]

On Fri, Nov 13, 2009 at 03:51:02PM -0800, Andrew Morton wrote:
> > ...
> >
> > +extern struct mutex pm_mutex;
> 
> Am a bit worried by the new mutex.

It's not a new mutex, just the existing one already used by suspend.
I only extended it's coverage to two more code paths.

> 
> > -extern struct mutex pm_mutex;
> > +static inline void lock_hibernation(void) {}
> > +static inline void unlock_hibernation(void) {}
> > +
> > +#else
> > +
> > +/* Let some subsystems like memory hotadd exclude hibernation */
> > +
> > +static inline void lock_hibernation(void)
> > +{
> > +	mutex_lock(&pm_mutex);
> > +}
> > +
> > +static inline void unlock_hibernation(void)
> > +{
> > +	mutex_unlock(&pm_mutex);
> > +}
> > +#endif
> 
> Has this been carefully reviewed and lockdep-tested to ensure that we
> didn't introduce any ab/ba nasties?

It's a "outer" global mutex for both, so I don't expect ABBA issues.

I tested hotadd/hotremove with lockdep and nothing showed up.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.

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