Re: [RFC PATCH 2/12] memory-hogplug : check memory offline in offline_pages
From: KOSAKI Motohiro <hidden>
Date: 2012-06-28 05:26:43
Also in:
linux-acpi, linux-mm, lkml
On Wed, Jun 27, 2012 at 1:44 AM, Yasuaki Ishimatsu [off-list ref] wrote:
When offline_pages() is called to offlined memory, the function fails sin=
ce
all memory has been offlined. In this case, the function should succeed. The patch adds the check function into offline_pages().
I don't understand your point. I think following misoperation should fail. Otherwise administrator have no way to know their fault. $ echo offline > memoryN/state $ echo offline > memoryN/state In general, we don't like to ignore an error except the standard require it= .
CC: Len Brown <redacted> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: Paul Mackerras <redacted> CC: Christoph Lameter <redacted> Cc: Minchan Kim <redacted> CC: Andrew Morton <akpm@linux-foundation.org> CC: KOSAKI Motohiro <redacted> CC: Wen Congyang <redacted> Signed-off-by: Yasuaki Ishimatsu <redacted> --- =A0drivers/base/memory.c =A0| =A0 20 ++++++++++++++++++++ =A0include/linux/memory.h | =A0 =A01 + =A0mm/memory_hotplug.c =A0 =A0| =A0 =A05 +++++ =A03 files changed, 26 insertions(+) Index: linux-3.5-rc4/drivers/base/memory.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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--- linux-3.5-rc4.orig/drivers/base/memory.c =A0 =A02012-06-26 13:28:16.7=
26211752 +0900
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+++ linux-3.5-rc4/drivers/base/memory.c 2012-06-26 13:34:22.423639904 +09=
00
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@@ -70,6 +70,26 @@ void unregister_memory_isolate_notifier(=A0} =A0EXPORT_SYMBOL(unregister_memory_isolate_notifier); +bool memory_is_offline(unsigned long start_pfn, unsigned long end_pfn)
I dislike this function name. 'memory' is too vague to me.
+{
+ =A0 =A0 =A0 struct memory_block *mem;
+ =A0 =A0 =A0 struct mem_section *section;
+ =A0 =A0 =A0 unsigned long pfn, section_nr;
+
+ =A0 =A0 =A0 for (pfn =3D start_pfn; pfn < end_pfn; pfn +=3D PAGES_PER_S=ECTION) {+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 section_nr =3D pfn_to_section_nr(pfn); + =A0 =A0 =A0 =A0 =A0 =A0 =A0 section =3D __nr_to_section(section_nr); + =A0 =A0 =A0 =A0 =A0 =A0 =A0 mem =3D find_memory_block(section);
This seems to have strong sparse dependency. Hm, I wonder why memory-hotplug.c can enable when X86_64_ACPI_NUMA. # eventually, we can have this option just 'select SPARSEMEM' config MEMORY_HOTPLUG bool "Allow for memory hot-add" depends on SPARSEMEM || X86_64_ACPI_NUMA
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (!mem) + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 continue; + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (mem->state =3D=3D MEM_OFFLINE) + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 continue; + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return false; + =A0 =A0 =A0 } + + =A0 =A0 =A0 return true; +} + =A0/* =A0* register_memory - Setup a sysfs device for a memory block =A0*/ Index: linux-3.5-rc4/include/linux/memory.h =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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--- linux-3.5-rc4.orig/include/linux/memory.h =A0 2012-06-25 04:53:04.000=
000000 +0900
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+++ linux-3.5-rc4/include/linux/memory.h =A0 =A0 =A0 =A02012-06-26 13:34:=
22.424639891 +0900
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@@ -120,6 +120,7 @@ extern int memory_isolate_notify(unsigne=A0extern struct memory_block *find_memory_block_hinted(struct mem_sectio=
n *,
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0struct memory_block *);
=A0extern struct memory_block *find_memory_block(struct mem_section *); +extern bool memory_is_offline(unsigned long start_pfn, unsigned long end=
_pfn);
=A0#define CONFIG_MEM_BLOCK_SIZE =A0(PAGES_PER_SECTION<<PAGE_SHIFT)
=A0enum mem_add_context { BOOT, HOTPLUG };
=A0#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
Index: linux-3.5-rc4/mm/memory_hotplug.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D==3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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--- linux-3.5-rc4.orig/mm/memory_hotplug.c =A0 =A0 =A02012-06-26 13:28:16=
.743211538 +0900
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+++ linux-3.5-rc4/mm/memory_hotplug.c =A0 2012-06-26 13:48:38.264940468 +=
0900
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@@ -887,6 +887,11 @@ static int __ref offline_pages(unsigned=A0 =A0 =A0 =A0lock_memory_hotplug(); + =A0 =A0 =A0 if (memory_is_offline(start_pfn, end_pfn)) { + =A0 =A0 =A0 =A0 =A0 =A0 =A0 ret =3D 0; + =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto out; + =A0 =A0 =A0 } + =A0 =A0 =A0 =A0zone =3D page_zone(pfn_to_page(start_pfn)); =A0 =A0 =A0 =A0node =3D zone_to_nid(zone); =A0 =A0 =A0 =A0nr_pages =3D end_pfn - start_pfn; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. =A0For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=3Dmailto:"dont@kvack.org"> email@kvack.org </a>