Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753720AbYKFD2n (ORCPT ); Wed, 5 Nov 2008 22:28:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752902AbYKFD2e (ORCPT ); Wed, 5 Nov 2008 22:28:34 -0500 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:48447 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752858AbYKFD2d (ORCPT ); Wed, 5 Nov 2008 22:28:33 -0500 Date: Thu, 06 Nov 2008 12:28:30 +0900 From: Yasunori Goto To: KAMEZAWA Hiroyuki Subject: Re: [linux-pm] [PATCH] hibernation should work ok with memory hotplug Cc: Nigel Cunningham , "Rafael J. Wysocki" , Dave Hansen , Matt Tolentino , linux-pm@lists.osdl.org, Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, pavel@suse.cz, Mel Gorman , Andy Whitcroft , Andrew Morton In-Reply-To: <20081106121212.e609476d.kamezawa.hiroyu@jp.fujitsu.com> References: <20081106110709.b168cc30.kamezawa.hiroyu@jp.fujitsu.com> <20081106121212.e609476d.kamezawa.hiroyu@jp.fujitsu.com> X-Mailer-Plugin: BkASPil for Becky!2 Ver.2.068 Message-Id: <20081106121916.4474.E1E9C6FF@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.45 [ja] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6720 Lines: 247 Hmm. I think simple mutex is enough. read/write lock is not necessary. Memory hotplug event is very rare, and there is no requirement of parallel execution. > On Thu, 6 Nov 2008 11:07:09 +0900 > KAMEZAWA Hiroyuki wrote: > > Okay. then we can add "kernel thread for calling add/remove memory" and say > > "PLEASE WAIT UNTIL HIBERNATION IS READY". > > > > I can try that by myself but doesn't have suitable machine.... > > I think I can show you pseudo code in hours. please wait a bit. > > > > How about this one ? as a start step ? > I have no test environment. So please take this as a sample. > -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 rwsemaphore for making them not to run at the same time. > > 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 also sleeps. > > Anyway, the most difficult thing is how to test this. > > > Signed-off-by: KAMEZAWA Hiroyuki > > mm/Kconfig | 2 - > mm/memory_hotplug.c | 61 +++++++++++++++++++++++++++++++++++++++++++++------- > 2 files changed, 54 insertions(+), 9 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 +31,13 @@ > > #include "internal.h" > > +struct rw_semaphore memhp_mutex; > + > +static int init_memhp_mutex(void) > +{ > + init_rwsem(&memhp_mutex); > +} > + > /* add this memory to iomem resource */ > static struct resource *register_memory_resource(u64 start, u64 size) > { > @@ -381,6 +388,7 @@ int online_pages(unsigned long pfn, unsi > int ret; > struct memory_notify arg; > > + down_read(&memhp_mutex); > arg.start_pfn = pfn; > arg.nr_pages = nr_pages; > arg.status_change_nid = -1; > @@ -392,6 +400,7 @@ int online_pages(unsigned long pfn, unsi > ret = memory_notify(MEM_GOING_ONLINE, &arg); > ret = notifier_to_errno(ret); > if (ret) { > + up_read(&memhp_mutex); > memory_notify(MEM_CANCEL_ONLINE, &arg); > return ret; > } > @@ -415,6 +424,7 @@ 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); > + up_read(&memhp_mutex); > return ret; > } > > @@ -436,7 +446,7 @@ int online_pages(unsigned long pfn, unsi > > if (onlined_pages) > memory_notify(MEM_ONLINE, &arg); > - > + up_read(&memhp_mutex); > return 0; > } > #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ > @@ -477,14 +487,18 @@ int add_memory(int nid, u64 start, u64 s > struct resource *res; > int ret; > > + down_read(&memhp_mutex); > res = register_memory_resource(start, size); > - if (!res) > + if (!res) { > + up_read(&memhp_mutex); > return -EEXIST; > - > + } > if (!node_online(nid)) { > pgdat = hotadd_new_pgdat(nid, start); > - if (!pgdat) > + if (!pgdat) { > + up_read(&memhp_mutex); > return -ENOMEM; > + } > new_pgdat = 1; > } > > @@ -508,7 +522,7 @@ int add_memory(int nid, u64 start, u64 s > */ > BUG_ON(ret); > } > - > + up_read(&memhp_mutex); > return ret; > error: > /* rollback pgdat allocation and others */ > @@ -517,10 +531,12 @@ error: > if (res) > release_memory_resource(res); > > + up_read(&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 +766,23 @@ 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; > > + down_read(&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) { > + up_read(&memhp_mutex); > return ret; > - > + } > arg.start_pfn = start_pfn; > arg.nr_pages = nr_pages; > arg.status_change_nid = -1; > @@ -838,6 +857,7 @@ repeat: > writeback_set_ratelimit(); > > memory_notify(MEM_OFFLINE, &arg); > + up_read(&memhp_mutex); > return 0; > > failed_removal: > @@ -846,7 +866,7 @@ failed_removal: > memory_notify(MEM_CANCEL_OFFLINE, &arg); > /* pushback to free area */ > undo_isolate_page_range(start_pfn, end_pfn); > - > + up_read(&memhp_mutex); > return ret; > } > #else > @@ -856,3 +876,34 @@ 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) > +{ > + int ret; > + > + switch(action) { > + case PM_HIBERNATION_PREPARE: > + down_write(&memhp_mutex); > + break; > + case PM_POST_HIBERNATION: > + up_write(&memhp_mutex); > + break; > + case PM_RESTORE_PREPARE: > + down_write(&memhp_mutex); > + break; > + case PM_POST_RESTORE: > + up_write(&memhp_mutex); > + break; > + default: > + break; > + } > + return NOTIFY_OK; > +} > +#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 > -- Yasunori Goto -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/