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Date: Fri, 13 Nov 2009 20:13:23 +0900 (JST)
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: Andi Kleen <andi@...stfloor.org>
Cc: kosaki.motohiro@...fujitsu.com, akpm@...ux-foundation.org,
linux-mm@...ck.org, gerald.schaefer@...ibm.com, rjw@...k.pl,
linux-kernel@...r.kernel.org, Yasunori Goto <y-goto@...fujitsu.com>
Subject: Re: [PATCH] Allow memory hotplug and hibernation in the same kernel
(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@...ibm.com
> Cc: rjw@...k.pl
>
> Signed-off-by: Andi Kleen <ak@...ux.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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