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() chacks 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]>
---
mm/memory_hotplug.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 29d8693..7649f7c 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1943,7 +1943,7 @@ void try_offline_node(int nid)
if (!PageSlab(pgdat_page) && !PageCompound(pgdat_page))
/* node data is allocated from boot memory */
- return;
+ goto out;
/* free waittable in each zone */
for (i = 0; i < MAX_NR_ZONES; i++) {
@@ -1957,6 +1957,7 @@ void try_offline_node(int nid)
vfree(zone->wait_table);
}
+out:
/*
* Since there is no way to guarentee the address of pgdat/zone is not
* on stack of any kernel threads or used by other kernel objects
--
1.8.3.1
On Mon, 2014-10-20 at 19:05 +0900, Yasuaki Ishimatsu wrote:
:
> 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() chacks wether pgdat is set
s/chacks/checks
> 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]>
>
> ---
> mm/memory_hotplug.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 29d8693..7649f7c 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1943,7 +1943,7 @@ void try_offline_node(int nid)
>
> if (!PageSlab(pgdat_page) && !PageCompound(pgdat_page))
> /* node data is allocated from boot memory */
> - return;
> + goto out;
Do we still need this if-statement? That is, do we have to skip the
for-loop below even though it checks with is_vmalloc_addr()?
Thanks,
-Toshi
> /* free waittable in each zone */
> for (i = 0; i < MAX_NR_ZONES; i++) {
> @@ -1957,6 +1957,7 @@ void try_offline_node(int nid)
> vfree(zone->wait_table);
> }
>
> +out:
> /*
> * Since there is no way to guarentee the address of pgdat/zone is not
> * on stack of any kernel threads or used by other kernel objects
(2014/10/22 1:56), Toshi Kani wrote:
> On Mon, 2014-10-20 at 19:05 +0900, Yasuaki Ishimatsu wrote:
> :
>> 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() chacks wether pgdat is set
>
> s/chacks/checks
I'll update it.
>
>
>> 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]>
>>
>> ---
>> mm/memory_hotplug.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 29d8693..7649f7c 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1943,7 +1943,7 @@ void try_offline_node(int nid)
>>
>> if (!PageSlab(pgdat_page) && !PageCompound(pgdat_page))
>> /* node data is allocated from boot memory */
>> - return;
>> + goto out;
>
> Do we still need this if-statement? That is, do we have to skip the
> for-loop below even though it checks with is_vmalloc_addr()?
You are right. The if-statement is not necessary. So the issue can be
fixed by just removing the if-statement.
I'll post updated patch soon.
Thanks,
Yasuaki Ishimatsu
>
> Thanks,
> -Toshi
>
>
>> /* free waittable in each zone */
>> for (i = 0; i < MAX_NR_ZONES; i++) {
>> @@ -1957,6 +1957,7 @@ void try_offline_node(int nid)
>> vfree(zone->wait_table);
>> }
>>
>> +out:
>> /*
>> * Since there is no way to guarentee the address of pgdat/zone is not
>> * on stack of any kernel threads or used by other kernel objects
>
>