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(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 29d8693..252e1db 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -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;
--
1.8.3.1
On Wed, 2014-10-22 at 16:51 +0900, Yasuaki Ishimatsu wrote:
> 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]>
Thanks for the update. It looks good.
Reviewed-by: Toshi Kani <[email protected]>
-Toshi
(2014/10/23 4:02), Toshi Kani wrote:
> On Wed, 2014-10-22 at 16:51 +0900, Yasuaki Ishimatsu wrote:
>> 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]>
>
> Thanks for the update. It looks good.
>
> Reviewed-by: Toshi Kani <[email protected]>
Thank you for your review.
Thanks,
Yasuaki Ishimatasu
>
> -Toshi
>
>
>