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Date: Thu, 9 May 2019 12:43:02 +0000 From: Wei Yang <richard.weiyang@...il.com> To: David Hildenbrand <david@...hat.com> Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org, linux-sh@...r.kernel.org, akpm@...ux-foundation.org, Dan Williams <dan.j.williams@...el.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, "mike.travis@....com" <mike.travis@....com>, Ingo Molnar <mingo@...nel.org>, Andrew Banman <andrew.banman@....com>, Oscar Salvador <osalvador@...e.de>, Michal Hocko <mhocko@...e.com>, Pavel Tatashin <pasha.tatashin@...een.com>, Qian Cai <cai@....pw>, Wei Yang <richard.weiyang@...il.com>, Arun KS <arunks@...eaurora.org>, Mathieu Malaterre <malat@...ian.org> Subject: Re: [PATCH v2 4/8] mm/memory_hotplug: Create memory block devices after arch_add_memory() On Tue, May 07, 2019 at 08:38:00PM +0200, David Hildenbrand wrote: >Only memory to be added to the buddy and to be onlined/offlined by >user space using memory block devices needs (and should have!) memory >block devices. > >Factor out creation of memory block devices Create all devices after >arch_add_memory() succeeded. We can later drop the want_memblock parameter, >because it is now effectively stale. > >Only after memory block devices have been added, memory can be onlined >by user space. This implies, that memory is not visible to user space at >all before arch_add_memory() succeeded. > >Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> >Cc: "Rafael J. Wysocki" <rafael@...nel.org> >Cc: David Hildenbrand <david@...hat.com> >Cc: "mike.travis@....com" <mike.travis@....com> >Cc: Andrew Morton <akpm@...ux-foundation.org> >Cc: Ingo Molnar <mingo@...nel.org> >Cc: Andrew Banman <andrew.banman@....com> >Cc: Oscar Salvador <osalvador@...e.de> >Cc: Michal Hocko <mhocko@...e.com> >Cc: Pavel Tatashin <pasha.tatashin@...een.com> >Cc: Qian Cai <cai@....pw> >Cc: Wei Yang <richard.weiyang@...il.com> >Cc: Arun KS <arunks@...eaurora.org> >Cc: Mathieu Malaterre <malat@...ian.org> >Signed-off-by: David Hildenbrand <david@...hat.com> >--- > drivers/base/memory.c | 70 ++++++++++++++++++++++++++---------------- > include/linux/memory.h | 2 +- > mm/memory_hotplug.c | 15 ++++----- > 3 files changed, 53 insertions(+), 34 deletions(-) > >diff --git a/drivers/base/memory.c b/drivers/base/memory.c >index 6e0cb4fda179..862c202a18ca 100644 >--- a/drivers/base/memory.c >+++ b/drivers/base/memory.c >@@ -701,44 +701,62 @@ static int add_memory_block(int base_section_nr) > return 0; > } > >+static void unregister_memory(struct memory_block *memory) >+{ >+ BUG_ON(memory->dev.bus != &memory_subsys); >+ >+ /* drop the ref. we got via find_memory_block() */ >+ put_device(&memory->dev); >+ device_unregister(&memory->dev); >+} >+ > /* >- * need an interface for the VM to add new memory regions, >- * but without onlining it. >+ * Create memory block devices for the given memory area. Start and size >+ * have to be aligned to memory block granularity. Memory block devices >+ * will be initialized as offline. > */ >-int hotplug_memory_register(int nid, struct mem_section *section) >+int hotplug_memory_register(unsigned long start, unsigned long size) > { >- int ret = 0; >+ unsigned long block_nr_pages = memory_block_size_bytes() >> PAGE_SHIFT; >+ unsigned long start_pfn = PFN_DOWN(start); >+ unsigned long end_pfn = start_pfn + (size >> PAGE_SHIFT); >+ unsigned long pfn; > struct memory_block *mem; >+ int ret = 0; > >- mutex_lock(&mem_sysfs_mutex); >+ BUG_ON(!IS_ALIGNED(start, memory_block_size_bytes())); >+ BUG_ON(!IS_ALIGNED(size, memory_block_size_bytes())); After this change, the call flow looks like this: add_memory_resource check_hotplug_memory_range hotplug_memory_register Since in check_hotplug_memory_range() has checked the boundary, do we need to check here again? -- Wei Yang Help you, Help me
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