linux-kernel - Re: [PATCH] mm/alloc: fallback to first node if the wanted node offline

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Message-ID: <20181204083428.emgcaomg6vulknaq@master>
Date:   Tue, 4 Dec 2018 08:34:28 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     Pingfan Liu <kernelfans@...il.com>
Cc:     richard.weiyang@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH] mm/alloc: fallback to first node if the wanted node
 offline

On Tue, Dec 04, 2018 at 03:20:13PM +0800, Pingfan Liu wrote:
>On Tue, Dec 4, 2018 at 2:54 PM Wei Yang <richard.weiyang@...il.com> wrote:
>>
>> On Tue, Dec 04, 2018 at 11:05:57AM +0800, Pingfan Liu wrote:
>> >During my test on some AMD machine, with kexec -l nr_cpus=x option, the
>> >kernel failed to bootup, because some node's data struct can not be allocated,
>> >e.g, on x86, initialized by init_cpu_to_node()->init_memory_less_node(). But
>> >device->numa_node info is used as preferred_nid param for
>>
>> could we fix the preferred_nid before passed to
>> __alloc_pages_nodemask()?
>>
>Yes, we can doit too, but what is the gain?

node_zonelist() is used some places. If we are sure where the problem
is, it is not necessary to spread to other places.

>
>> BTW, I don't catch the function call flow to this point. Would you mind
>> giving me some hint?
>>
>You can track the code along slab_alloc() ->...->__alloc_pages_nodemask()

slab_alloc() pass NUMA_NO_NODE down, so I am lost in where the
preferred_nid is assigned.

>
>Thanks,
>Pingfan

-- 
Wei Yang
Help you, Help me