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Date: Wed, 05 Aug 2015 07:47:07 -0700
From: Dave Hansen <dave.hansen@intel.com>
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To: Xishi Qiu <qiuxishi@huawei.com>
CC: Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@suse.de>,
        Vlastimil Babka <vbabka@suse.cz>, Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@suse.cz>, iamjoonsoo.kim@lge.com,
        alexander.h.duyck@redhat.com, sasha.levin@oracle.com,
        Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: add the block to the tail of the list in expand()
References: <55BB4027.7080200@huawei.com> <55BC0392.2070205@intel.com> <55BECC85.7050206@huawei.com> <55BEE99E.8090901@intel.com> <55C011A6.1090003@huawei.com> <55C0CBC3.2000602@intel.com> <55C1C132.2010805@huawei.com>
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On 08/05/2015 12:54 AM, Xishi Qiu wrote:
> I add some debug code like this, but it doesn't trigger the dump_stack().
...
> +         if (!list_empty(&area->free_list[migratetype])) {
> +                 printk("expand(), the list is not empty\n");
> +                 dump_stack();
> +         }
> +

That will probably not trigger unless you have allocations that are
falling back and converting other pageblocks from other migratetypes.