From: Wei Yang <richard.weiyang@gmail.com>
To: Pingfan Liu <kernelfans@gmail.com>
Cc: mhocko@kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH] mm/alloc: fallback to first node if the wanted node offline
Date: Tue, 4 Dec 2018 08:40:52 +0000 [thread overview]
Message-ID: <20181204084052.gpwwlnp6n2zehjy5@master> (raw)
In-Reply-To: <CAFgQCTv56drDBx-sTr6KdeQNKJnojG3g_a-k8wKe_q2y9w9NtA@mail.gmail.com>
On Tue, Dec 04, 2018 at 04:20:32PM +0800, Pingfan Liu wrote:
>On Tue, Dec 4, 2018 at 3:22 PM Michal Hocko <mhocko@kernel.org> wrote:
>>
>> On Tue 04-12-18 11:05:57, 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
>> > __alloc_pages_nodemask(), which causes NULL reference
>> > ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
>> > This patch tries to fix the issue by falling back to the first online node,
>> > when encountering such corner case.
>>
>> We have seen similar issues already and the bug was usually that the
>> zonelists were not initialized yet or the node is completely bogus.
>> Zonelists should be initialized by build_all_zonelists quite early so I
>> am wondering whether the later is the case. What is the actual node
>> number the device is associated with?
>>
>The device's node num is 2. And in my case, I used nr_cpus param. Due
>to init_cpu_to_node() initialize all the possible node. It is hard
>for me to figure out without this param, how zonelists is accessed
>before page allocator works.
If my understanding is correct, we can't do page alloc before zonelist
is initialized.
I guess Michal's point is to figure out this reason.
>
>> Your patch is not correct btw, because we want to fallback into the node in
>> the distance order rather into the first online node.
>> --
>What about this:
>+extern int find_next_best_node(int node, nodemask_t *used_node_mask);
>+
> /*
> * We get the zone list from the current node and the gfp_mask.
> * This zone list contains a maximum of MAXNODES*MAX_NR_ZONES zones.
>@@ -453,6 +455,11 @@ static inline int gfp_zonelist(gfp_t flags)
> */
> static inline struct zonelist *node_zonelist(int nid, gfp_t flags)
> {
>+ if (unlikely(!node_online(nid))) {
>+ nodemask_t used_mask;
>+ nodes_complement(used_mask, node_online_map);
>+ nid = find_next_best_node(nid, &used_mask);
>+ }
> return NODE_DATA(nid)->node_zonelists + gfp_zonelist(flags);
> }
>
>I just finished the compiling, not test it yet, since the machine is
>not on hand yet. It needs some time to get it again.
>
>Thanks,
>Pingfan
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2018-12-04 8:40 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 3:05 [PATCH] mm/alloc: fallback to first node if the wanted node offline Pingfan Liu
2018-12-04 3:53 ` David Rientjes
2018-12-04 7:16 ` Pingfan Liu
2018-12-05 5:49 ` Pingfan Liu
2018-12-05 19:00 ` David Rientjes
2018-12-04 6:54 ` Wei Yang
2018-12-04 7:20 ` Pingfan Liu
2018-12-04 8:34 ` Wei Yang
2018-12-04 8:52 ` Pingfan Liu
2018-12-04 9:09 ` Wei Yang
2018-12-05 5:50 ` Pingfan Liu
2018-12-04 7:22 ` Michal Hocko
2018-12-04 8:20 ` Pingfan Liu
2018-12-04 8:40 ` Wei Yang [this message]
2018-12-04 8:56 ` Pingfan Liu
2018-12-04 8:56 ` Michal Hocko
2018-12-04 14:42 ` Vlastimil Babka
2018-12-05 5:38 ` Pingfan Liu
2018-12-05 9:21 ` Michal Hocko
2018-12-05 9:29 ` Pingfan Liu
2018-12-05 9:40 ` Vlastimil Babka
2018-12-06 3:07 ` Pingfan Liu
2018-12-06 8:28 ` Michal Hocko
2018-12-06 10:03 ` Pingfan Liu
2018-12-06 10:44 ` Pingfan Liu
2018-12-06 12:11 ` Michal Hocko
2018-12-07 2:56 ` Pingfan Liu
2018-12-07 7:53 ` Michal Hocko
2018-12-07 9:40 ` Pingfan Liu
2018-12-07 11:30 ` Michal Hocko
2018-12-07 13:20 ` Pingfan Liu
2018-12-07 14:22 ` Michal Hocko
2018-12-07 14:27 ` Pingfan Liu
2018-12-07 14:50 ` Michal Hocko
2018-12-07 15:56 ` Michal Hocko
2018-12-10 4:00 ` Pingfan Liu
2018-12-10 7:57 ` Pingfan Liu
2018-12-10 12:37 ` Michal Hocko
2018-12-11 8:05 ` Pingfan Liu
2018-12-11 9:44 ` Michal Hocko
2018-12-12 8:33 ` Pingfan Liu
2018-12-12 8:31 ` Pingfan Liu
2018-12-12 11:53 ` Michal Hocko
2018-12-13 8:37 ` Pingfan Liu
2018-12-13 9:04 ` Pingfan Liu
2018-12-17 13:29 ` Michal Hocko
2018-12-20 7:19 ` Pingfan Liu
2018-12-20 9:19 ` Michal Hocko
2019-01-08 14:34 ` Michal Hocko
2019-01-09 3:13 ` Pingfan Liu
2019-01-11 3:12 ` Pingfan Liu
2019-01-11 9:23 ` Michal Hocko
2018-12-17 12:57 ` Michal Hocko
2018-12-05 9:43 ` Michal Hocko
2018-12-06 3:34 ` Pingfan Liu
2018-12-06 7:23 ` Michal Hocko
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