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Message-ID: <20090222223547.GH26999@elf.ucw.cz>
Date: Sun, 22 Feb 2009 23:35:47 +0100
From: Pavel Machek <pavel@...e.cz>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
"Rafael J. Wysocki" <rjw@...k.pl>
Cc: gerald.schaefer@...ibm.com, ncunningham@...a.org.au,
Dave Hansen <dave@...ux.vnet.ibm.com>,
Tolentino <matthew.e.tolentino@...el.com>,
Hansen <haveblue@...ibm.com>, linux-pm@...ts.osdl.org,
Matt@...p1.linux-foundation.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, Dave@...p1.linux-foundation.org,
Mel Gorman <mel@...net.ie>, Andy@...p1.linux-foundation.org,
Whitcroft <apw@...dowen.org>,
Yasunori Goto <y-goto@...fujitsu.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC][PATCH] add mutex and hibernation notifier to memory
hotplug.
Hi!
> Sorry, I can't test this now but I post this while discussion is hot.
>
> I'll test this with CONFIG_PM_DEBUG's hibernation test mode if I can.
> (But may take a long time..)
>
> Any feedback is welcome.
I lost the track here... but this may still be required... ? And given
that there will be both mem hotplug and swsusp in SLE11...
Pavel
> Thanks,
> -Kame
> ==
> Now, MEMORY_HOTPLUG and HIBERNATION is mutually exclusive in Kconfig.
> That's because
> - memory hotplug changes pgdat/zone/memmap range.
> - hibernation countes # of memory based on pgdate/zone/memmap.
>
> This patch adds mutex for disallowing them to run simultaneously.
>
> IIUC, add_memory() is called from following places.
> - probe interface
> - acpi handler
> It seems both can sleep. (acpi handler uses sleepable memory allocator etc...)
> online/offline handlers can sleep.
> hibernation notifier can sleep, too.
>
> This also makes all memory hotplug event not to happen at the same time.
> (memory hotplug is not busy code.)
>
> Anyway, the most difficult thing is how to test this.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>
> mm/Kconfig | 5 ----
> mm/memory_hotplug.c | 60 +++++++++++++++++++++++++++++++++++++++++++++-------
> 2 files changed, 53 insertions(+), 12 deletions(-)
>
> Index: linux-2.6.27.4/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.27.4.orig/mm/memory_hotplug.c
> +++ linux-2.6.27.4/mm/memory_hotplug.c
> @@ -31,6 +31,8 @@
>
> #include "internal.h"
>
> +DEFINE_MUTEX(memhp_mutex);
> +
> /* add this memory to iomem resource */
> static struct resource *register_memory_resource(u64 start, u64 size)
> {
> @@ -381,6 +383,7 @@ int online_pages(unsigned long pfn, unsi
> int ret;
> struct memory_notify arg;
>
> + mutex_lock(&memhp_mutex);
> arg.start_pfn = pfn;
> arg.nr_pages = nr_pages;
> arg.status_change_nid = -1;
> @@ -392,6 +395,7 @@ int online_pages(unsigned long pfn, unsi
> ret = memory_notify(MEM_GOING_ONLINE, &arg);
> ret = notifier_to_errno(ret);
> if (ret) {
> + mutex_unlock(&memhp_mutex);
> memory_notify(MEM_CANCEL_ONLINE, &arg);
> return ret;
> }
> @@ -415,6 +419,7 @@ int online_pages(unsigned long pfn, unsi
> printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
> nr_pages, pfn);
> memory_notify(MEM_CANCEL_ONLINE, &arg);
> + mutex_unlock(&memhp_mutex);
> return ret;
> }
>
> @@ -436,7 +441,7 @@ int online_pages(unsigned long pfn, unsi
>
> if (onlined_pages)
> memory_notify(MEM_ONLINE, &arg);
> -
> + mutex_unlock(&memhp_mutex);
> return 0;
> }
> #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
> @@ -477,14 +482,18 @@ int add_memory(int nid, u64 start, u64 s
> struct resource *res;
> int ret;
>
> + mutex_lock(&memhp_mutex);
> res = register_memory_resource(start, size);
> - if (!res)
> + if (!res) {
> + mutex_unlock(&memhp_mutex);
> return -EEXIST;
> -
> + }
> if (!node_online(nid)) {
> pgdat = hotadd_new_pgdat(nid, start);
> - if (!pgdat)
> + if (!pgdat) {
> + mutex_unlock(&memhp_mutex);
> return -ENOMEM;
> + }
> new_pgdat = 1;
> }
>
> @@ -508,7 +517,7 @@ int add_memory(int nid, u64 start, u64 s
> */
> BUG_ON(ret);
> }
> -
> + mutex_unlock(&memhp_mutex);
> return ret;
> error:
> /* rollback pgdat allocation and others */
> @@ -517,10 +526,12 @@ error:
> if (res)
> release_memory_resource(res);
>
> + mutex_unlock(&memhp_mutex);
> return ret;
> }
> EXPORT_SYMBOL_GPL(add_memory);
>
> +
> #ifdef CONFIG_MEMORY_HOTREMOVE
> /*
> * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
> @@ -750,20 +761,23 @@ int offline_pages(unsigned long start_pf
> return -EINVAL;
> if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
> return -EINVAL;
> +
> /* This makes hotplug much easier...and readable.
> we assume this for now. .*/
> if (!test_pages_in_a_zone(start_pfn, end_pfn))
> return -EINVAL;
>
> + mutex_lock(&memhp_mutex);
> zone = page_zone(pfn_to_page(start_pfn));
> node = zone_to_nid(zone);
> nr_pages = end_pfn - start_pfn;
>
> /* set above range as isolated */
> ret = start_isolate_page_range(start_pfn, end_pfn);
> - if (ret)
> + if (ret) {
> + mutex_unlock(&memhp_mutex);
> return ret;
> -
> + }
> arg.start_pfn = start_pfn;
> arg.nr_pages = nr_pages;
> arg.status_change_nid = -1;
> @@ -838,6 +852,7 @@ repeat:
> writeback_set_ratelimit();
>
> memory_notify(MEM_OFFLINE, &arg);
> + mutex_unlock(&memhp_mutex);
> return 0;
>
> failed_removal:
> @@ -846,7 +861,7 @@ failed_removal:
> memory_notify(MEM_CANCEL_OFFLINE, &arg);
> /* pushback to free area */
> undo_isolate_page_range(start_pfn, end_pfn);
> -
> + mutex_unlock(&memhp_mutex);
> return ret;
> }
> #else
> @@ -856,3 +871,43 @@ int remove_memory(u64 start, u64 size)
> }
> EXPORT_SYMBOL_GPL(remove_memory);
> #endif /* CONFIG_MEMORY_HOTREMOVE */
> +
> +
> +#ifdef CONFIG_HIBERNATION
> +
> +int memhp_hibenation_callback(struct notifier_block *self,
> + unsigned long action,
> + void *arg)
> +{
> + switch(action) {
> + case PM_HIBERNATION_PREPARE:
> + mutex_lock(&memhp_mutex);
> + break;
> + case PM_POST_HIBERNATION:
> + mutex_unlock(&memhp_mutex);
> + break;
> + case PM_RESTORE_PREPARE:
> + mutex_lock(&memhp_mutex);
> + break;
> + case PM_POST_RESTORE:
> + mutex_unlock(&memhp_mutex);
> + break;
> + default:
> + break;
> + }
> + return NOTIFY_OK;
> +}
> +static struct notifier_block memhp_notifier {
> + .notifier_call = memhp_hibernation_callback,
> +};
> +
> +static int __init memhp_hibernation_notifier_init(void)
> +{
> + register_pm_notifier(&memhp_notifier);
> + return 0;
> +}
> +__initcall(&memhp_hibernation_notifier_init);
> +
> +#endif
> +
> +
> Index: linux-2.6.27.4/mm/Kconfig
> ===================================================================
> --- linux-2.6.27.4.orig/mm/Kconfig
> +++ linux-2.6.27.4/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 && ARCH_ENABLE_MEMORY_HOTPLUG
> + depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
> depends on (IA64 || X86 || PPC64 || SUPERH || S390)
>
> -comment "Memory hotplug is currently incompatible with Software Suspend"
> - depends on SPARSEMEM && HOTPLUG && HIBERNATION
> -
> config MEMORY_HOTPLUG_SPARSE
> def_bool y
> depends on SPARSEMEM && MEMORY_HOTPLUG
>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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