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From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Date: Sun, 26 May 2013 07:49:33 -0400
Message-ID: <CAHGf_=rOLAYrpkLQiM53jn-bHAuxw=rRZP0+pNV-8EUinJzP7w@mail.gmail.com>
Subject: Re: [PATCH v3 1/6] mm/memory-hotplug: fix lowmem count overflow when
 offline pages
To: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Michal Hocko <mhocko@suse.cz>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        David Rientjes <rientjes@google.com>, Jiang Liu <jiang.liu@huawei.com>,
        Tang Chen <tangchen@cn.fujitsu.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org
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On Sun, May 26, 2013 at 1:58 AM, Wanpeng Li <liwanp@linux.vnet.ibm.com> wrote:
> Changelog:
>  v1 -> v2:
>         * show number of HighTotal before hotremove
>         * remove CONFIG_HIGHMEM
>         * cc stable kernels
>         * add Michal reviewed-by
>
> Logic memory-remove code fails to correctly account the Total High Memory
> when a memory block which contains High Memory is offlined as shown in the
> example below. The following patch fixes it.
>
> Stable for 2.6.24+.
>
> Before logic memory remove:
>
> MemTotal:        7603740 kB
> MemFree:         6329612 kB
> Buffers:           94352 kB
> Cached:           872008 kB
> SwapCached:            0 kB
> Active:           626932 kB
> Inactive:         519216 kB
> Active(anon):     180776 kB
> Inactive(anon):   222944 kB
> Active(file):     446156 kB
> Inactive(file):   296272 kB
> Unevictable:           0 kB
> Mlocked:               0 kB
> HighTotal:       7294672 kB
> HighFree:        5704696 kB
> LowTotal:         309068 kB
> LowFree:          624916 kB
>
> After logic memory remove:
>
> MemTotal:        7079452 kB
> MemFree:         5805976 kB
> Buffers:           94372 kB
> Cached:           872000 kB
> SwapCached:            0 kB
> Active:           626936 kB
> Inactive:         519236 kB
> Active(anon):     180780 kB
> Inactive(anon):   222944 kB
> Active(file):     446156 kB
> Inactive(file):   296292 kB
> Unevictable:           0 kB
> Mlocked:               0 kB
> HighTotal:       7294672 kB
> HighFree:        5181024 kB
> LowTotal:       4294752076 kB
> LowFree:          624952 kB
>
> Reviewed-by: Michal Hocko <mhocko@suse.cz>
> Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> ---
>  mm/page_alloc.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 98cbdf6..23b921f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6140,6 +6140,8 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
>                 list_del(&page->lru);
>                 rmv_page_order(page);
>                 zone->free_area[order].nr_free--;
> +               if (PageHighMem(page))
> +                       totalhigh_pages -= 1 << order;
>                 for (i = 0; i < (1 << order); i++)
>                         SetPageReserved((page+i));
>                 pfn += (1 << order);

Hm. I already NAKed and you didn't answered my question. isn't it?
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