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

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Date:   Tue, 4 Dec 2018 16:52:52 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     richard.weiyang@...il.com
Cc:     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 4, 2018 at 4:34 PM Wei Yang <richard.weiyang@...il.com> wrote:
>
> 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.
>
You can follow:
[    5.773618]  new_slab+0xa9/0x570
[    5.773618]  ___slab_alloc+0x375/0x540
[    5.773618]  ? pinctrl_bind_pins+0x2b/0x2a0
where static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)

Thanks,
Pingfan