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memory-hotplug: Clear pgdat which is allocated by bootmem in try_offline_node()

PATCH In review Yasuaki Ishimatsu 2 participants 3 messages Oct 22, 2014

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Memory management Memory hot(un)plug
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Yasuaki Ishimatsu

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#0 lore raw

PATCH v2 1/1 memory-hotplug: Clear pgdat which is allocated by bootmem in try_offline_node()

When hot adding the same memory after hot removing a memory, the following messages are shown:

WARNING: CPU: 20 PID: 6 at mm/page_alloc.c:4968 free_area_init_node+0x3fe/0x426()
...
Call Trace:
 [<...>] dump_stack+0x46/0x58
 [<...>] warn_slowpath_common+0x81/0xa0
 [<...>] warn_slowpath_null+0x1a/0x20
 [<...>] free_area_init_node+0x3fe/0x426
 [<...>] ? up+0x32/0x50
 [<...>] hotadd_new_pgdat+0x90/0x110
 [<...>] add_memory+0xd4/0x200
 [<...>] acpi_memory_device_add+0x1aa/0x289
 [<...>] acpi_bus_attach+0xfd/0x204
 [<...>] ? device_register+0x1e/0x30
 [<...>] acpi_bus_attach+0x178/0x204
 [<...>] acpi_bus_scan+0x6a/0x90
 [<...>] ? acpi_bus_get_status+0x2d/0x5f
 [<...>] acpi_device_hotplug+0xe8/0x418
 [<...>] acpi_hotplug_work_fn+0x1f/0x2b
 [<...>] process_one_work+0x14e/0x3f0
 [<...>] worker_thread+0x11b/0x510
 [<...>] ? rescuer_thread+0x350/0x350
 [<...>] kthread+0xe1/0x100
 [<...>] ? kthread_create_on_node+0x1b0/0x1b0
 [<...>] ret_from_fork+0x7c/0xb0
 [<...>] ? kthread_create_on_node+0x1b0/0x1b0

The detaled explanation is as follows:

When hot removing memory, pgdat is set to 0 in try_offline_node(). But if the pgdat is allocated by bootmem allocator, the clearing step is skipped. And when hot adding the same memory, the uninitialized pgdat is reused. But free_area_init_node() checks wether pgdat is set to zero. As a result, free_area_init_node() hits WARN_ON().

This patch clears pgdat which is allocated by bootmem allocator in try_offline_node().

Signed-off-by Yasuaki Ishimatsu <[email protected]>
CC Zhang Zhen <[email protected]>
CC Wang Nan <[email protected]>
CC Tang Chen <[email protected]>
CC Toshi Kani <[email protected]>
CC Dave Hansen <[email protected]>
CC David Rientjes <[email protected]>

---
v2: remove check of pgdat_page

 mm/memory_hotplug.c | 5 -----
 1 file changed, 5 deletions(-)
mm/memory_hotplug.c +0 -5
index 29d8693..252e1db 100644
@@ -1912,7 +1912,6 @@ void try_offline_node(int nid)
 	unsigned long start_pfn = pgdat->node_start_pfn;
 	unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
 	unsigned long pfn;
-	struct page *pgdat_page = virt_to_page(pgdat);
 	int i;
 
 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {

@@ -1941,10 +1940,6 @@ void try_offline_node(int nid)
 	node_set_offline(nid);
 	unregister_one_node(nid);
 
-	if (!PageSlab(pgdat_page) && !PageCompound(pgdat_page))
-		/* node data is allocated from boot memory */
-		return;
-
 	/* free waittable in each zone */
 	for (i = 0; i < MAX_NR_ZONES; i++) {
 		struct zone *zone = pgdat->node_zones + i;
Signature · 8 lines
1.8.3.1


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Reviewed-by on v2 1/1
#1 lore raw
Quoted 37 lines · Yasuaki Ishimatsu

When hot adding the same memory after hot removing a memory, the following messages are shown:

WARNING: CPU: 20 PID: 6 at mm/page_alloc.c:4968 free_area_init_node+0x3fe/0x426()
...
Call Trace:
 [<...>] dump_stack+0x46/0x58
 [<...>] warn_slowpath_common+0x81/0xa0
 [<...>] warn_slowpath_null+0x1a/0x20
 [<...>] free_area_init_node+0x3fe/0x426
 [<...>] ? up+0x32/0x50
 [<...>] hotadd_new_pgdat+0x90/0x110
 [<...>] add_memory+0xd4/0x200
 [<...>] acpi_memory_device_add+0x1aa/0x289
 [<...>] acpi_bus_attach+0xfd/0x204
 [<...>] ? device_register+0x1e/0x30
 [<...>] acpi_bus_attach+0x178/0x204
 [<...>] acpi_bus_scan+0x6a/0x90
 [<...>] ? acpi_bus_get_status+0x2d/0x5f
 [<...>] acpi_device_hotplug+0xe8/0x418
 [<...>] acpi_hotplug_work_fn+0x1f/0x2b
 [<...>] process_one_work+0x14e/0x3f0
 [<...>] worker_thread+0x11b/0x510
 [<...>] ? rescuer_thread+0x350/0x350
 [<...>] kthread+0xe1/0x100
 [<...>] ? kthread_create_on_node+0x1b0/0x1b0
 [<...>] ret_from_fork+0x7c/0xb0
 [<...>] ? kthread_create_on_node+0x1b0/0x1b0

The detaled explanation is as follows:

When hot removing memory, pgdat is set to 0 in try_offline_node(). But if the pgdat is allocated by bootmem allocator, the clearing step is skipped. And when hot adding the same memory, the uninitialized pgdat is reused. But free_area_init_node() checks wether pgdat is set to zero. As a result, free_area_init_node() hits WARN_ON().

Quoted 4 lines

This patch clears pgdat which is allocated by bootmem allocator in try_offline_node().

Signed-off-by Yasuaki Ishimatsu <[email protected]>

Thanks for the update. It looks good.

Reviewed-by Toshi Kani <[email protected]>

-Toshi

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author
#2 lore raw
Quoted 41 lines · Toshi Kani
Quoted 40 lines · Yasuaki Ishimatsu

When hot adding the same memory after hot removing a memory, the following messages are shown:

WARNING: CPU: 20 PID: 6 at mm/page_alloc.c:4968 free_area_init_node+0x3fe/0x426()
...
Call Trace:
  [<...>] dump_stack+0x46/0x58
  [<...>] warn_slowpath_common+0x81/0xa0
  [<...>] warn_slowpath_null+0x1a/0x20
  [<...>] free_area_init_node+0x3fe/0x426
  [<...>] ? up+0x32/0x50
  [<...>] hotadd_new_pgdat+0x90/0x110
  [<...>] add_memory+0xd4/0x200
  [<...>] acpi_memory_device_add+0x1aa/0x289
  [<...>] acpi_bus_attach+0xfd/0x204
  [<...>] ? device_register+0x1e/0x30
  [<...>] acpi_bus_attach+0x178/0x204
  [<...>] acpi_bus_scan+0x6a/0x90
  [<...>] ? acpi_bus_get_status+0x2d/0x5f
  [<...>] acpi_device_hotplug+0xe8/0x418
  [<...>] acpi_hotplug_work_fn+0x1f/0x2b
  [<...>] process_one_work+0x14e/0x3f0
  [<...>] worker_thread+0x11b/0x510
  [<...>] ? rescuer_thread+0x350/0x350
  [<...>] kthread+0xe1/0x100
  [<...>] ? kthread_create_on_node+0x1b0/0x1b0
  [<...>] ret_from_fork+0x7c/0xb0
  [<...>] ? kthread_create_on_node+0x1b0/0x1b0

The detaled explanation is as follows:

When hot removing memory, pgdat is set to 0 in try_offline_node(). But if the pgdat is allocated by bootmem allocator, the clearing step is skipped. And when hot adding the same memory, the uninitialized pgdat is reused. But free_area_init_node() checks wether pgdat is set to zero. As a result, free_area_init_node() hits WARN_ON().

This patch clears pgdat which is allocated by bootmem allocator in try_offline_node().

Quoted 6 lines
Quoted 1 line
Signed-off-by Yasuaki Ishimatsu <[email protected]>

Thanks for the update. It looks good.

Reviewed-by Toshi Kani <[email protected]>

Thank you for your review.

Thanks,
Yasuaki Ishimatasu

Quoted 5 lines

-Toshi

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