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Date: Tue, 4 Nov 2014 09:50:27 +0800
From: Xishi Qiu <qiuxishi@...wei.com>
To: Tang Chen <tangchen@...fujitsu.com>
CC: <akpm@...ux-foundation.org>, <santosh.shilimkar@...com>,
<grygorii.strashko@...com>, <yinghai@...nel.org>,
<isimatu.yasuaki@...fujitsu.co>, <fabf@...net.be>,
<nzimmer@....com>, <wangnan0@...wei.com>, <vdavydov@...allels.com>,
<toshi.kani@...com>, <phacht@...ux.vnet.ibm.com>, <tj@...nel.org>,
<kirill.shutemov@...ux.intel.com>, <riel@...hat.com>,
<luto@...capital.net>, <hpa@...ux.intel.com>,
<aarcange@...hat.com>, <mgorman@...e.de>, <rientjes@...gle.com>,
<hannes@...xchg.org>, <linux-mm@...ck.org>,
<linux-kernel@...r.kernel.org>,
Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Subject: Re: [PATCH 1/2] mem-hotplug: Reset node managed pages when hot-adding
a new pgdat.
On 2014/10/31 17:46, Tang Chen wrote:
> In free_area_init_core(), zone->managed_pages is set to an approximate
> value for lowmem, and will be adjusted when the bootmem allocator frees
> pages into the buddy system. But free_area_init_core() is also called
> by hotadd_new_pgdat() when hot-adding memory. As a result, zone->managed_pages
> of the newly added node's pgdat is set to an approximate value in the
> very beginning. Even if the memory on that node has node been onlined,
> /sys/device/system/node/nodeXXX/meminfo has wrong value.
>
> hot-add node2 (memory not onlined)
> cat /sys/device/system/node/node2/meminfo
> Node 2 MemTotal: 33554432 kB
> Node 2 MemFree: 0 kB
> Node 2 MemUsed: 33554432 kB
> Node 2 Active: 0 kB
>
> This patch fixes this problem by reset node managed pages to 0 after hot-adding
> a new node.
>
> 1. Move reset_managed_pages_done from reset_node_managed_pages() to reset_all_zones_managed_pages()
> 2. Make reset_node_managed_pages() non-static
> 3. Call reset_node_managed_pages() in hotadd_new_pgdat() after pgdat is initialized
>
> Signed-off-by: Tang Chen <tangchen@...fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> ---
> include/linux/bootmem.h | 1 +
> mm/bootmem.c | 9 +++++----
> mm/memory_hotplug.c | 9 +++++++++
> mm/nobootmem.c | 8 +++++---
> 4 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
> index 4e2bd4c..0995c2d 100644
> --- a/include/linux/bootmem.h
> +++ b/include/linux/bootmem.h
> @@ -46,6 +46,7 @@ extern unsigned long init_bootmem_node(pg_data_t *pgdat,
> extern unsigned long init_bootmem(unsigned long addr, unsigned long memend);
>
> extern unsigned long free_all_bootmem(void);
> +extern void reset_node_managed_pages(pg_data_t *pgdat);
> extern void reset_all_zones_managed_pages(void);
>
> extern void free_bootmem_node(pg_data_t *pgdat,
> diff --git a/mm/bootmem.c b/mm/bootmem.c
> index 8a000ce..477be69 100644
> --- a/mm/bootmem.c
> +++ b/mm/bootmem.c
> @@ -243,13 +243,10 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
>
> static int reset_managed_pages_done __initdata;
>
> -static inline void __init reset_node_managed_pages(pg_data_t *pgdat)
> +void reset_node_managed_pages(pg_data_t *pgdat)
> {
> struct zone *z;
>
> - if (reset_managed_pages_done)
> - return;
> -
> for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
> z->managed_pages = 0;
> }
> @@ -258,8 +255,12 @@ void __init reset_all_zones_managed_pages(void)
> {
> struct pglist_data *pgdat;
>
> + if (reset_managed_pages_done)
> + return;
> +
> for_each_online_pgdat(pgdat)
> reset_node_managed_pages(pgdat);
> +
> reset_managed_pages_done = 1;
> }
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 29d8693..3ab01b2 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -31,6 +31,7 @@
> #include <linux/stop_machine.h>
> #include <linux/hugetlb.h>
> #include <linux/memblock.h>
> +#include <linux/bootmem.h>
>
> #include <asm/tlbflush.h>
>
> @@ -1096,6 +1097,14 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
> build_all_zonelists(pgdat, NULL);
> mutex_unlock(&zonelists_mutex);
>
> + /*
> + * zone->managed_pages is set to an approximate value in
> + * free_area_init_core(), which will cause
> + * /sys/device/system/node/nodeX/meminfo has wrong data.
> + * So reset it to 0 before any memory is onlined.
> + */
> + reset_node_managed_pages(pgdat);
> +
I aggree with you, we should reset it before online pages.
Thanks,
Xishi Qiu
> return pgdat;
> }
>
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index 7c7ab32..90b5046 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -145,12 +145,10 @@ static unsigned long __init free_low_memory_core_early(void)
>
> static int reset_managed_pages_done __initdata;
>
> -static inline void __init reset_node_managed_pages(pg_data_t *pgdat)
> +void reset_node_managed_pages(pg_data_t *pgdat)
> {
> struct zone *z;
>
> - if (reset_managed_pages_done)
> - return;
> for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
> z->managed_pages = 0;
> }
> @@ -159,8 +157,12 @@ void __init reset_all_zones_managed_pages(void)
> {
> struct pglist_data *pgdat;
>
> + if (reset_managed_pages_done)
> + return;
> +
> for_each_online_pgdat(pgdat)
> reset_node_managed_pages(pgdat);
> +
> reset_managed_pages_done = 1;
> }
>
--
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