From: David Hildenbrand <david@redhat.com>
To: Jia He <justin.he@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>
Cc: Baoquan He <bhe@redhat.com>, Kaly Xin <Kaly.Xin@arm.com>,
Chuhong Yuan <hslester96@gmail.com>,
linux-kernel@vger.kernel.org, Mike Rapoport <rppt@linux.ibm.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/3] mm/memory_hotplug: harden try_offline_node against bogus nid
Date: Mon, 6 Jul 2020 09:57:50 +0200 [thread overview]
Message-ID: <4b864877-1147-8336-5e9a-e89ac5c99be3@redhat.com> (raw)
In-Reply-To: <20200706011947.184166-3-justin.he@arm.com>
On 06.07.20 03:19, Jia He wrote:
> When testing the remove_memory path of dax pmem, there will be a panic with
> call trace:
> try_remove_memory+0x84/0x170
> remove_memory+0x38/0x58
> dev_dax_kmem_remove+0x3c/0x84 [kmem]
> device_release_driver_internal+0xfc/0x1c8
> device_release_driver+0x28/0x38
> bus_remove_device+0xd4/0x158
> device_del+0x160/0x3a0
> unregister_dev_dax+0x30/0x68
> devm_action_release+0x20/0x30
> release_nodes+0x150/0x240
> devres_release_all+0x6c/0x1d0
> device_release_driver_internal+0x10c/0x1c8
> driver_detach+0xac/0x170
> bus_remove_driver+0x64/0x130
> driver_unregister+0x34/0x60
> dax_pmem_exit+0x14/0xffc4 [dax_pmem]
> __arm64_sys_delete_module+0x18c/0x2d0
> el0_svc_common.constprop.2+0x78/0x168
> do_el0_svc+0x34/0xa0
> el0_sync_handler+0xe0/0x188
> el0_sync+0x164/0x180
>
> It is caused by the bogus nid (-1). Although the root cause is pmem dax
> translates from pxm to node_id incorrectly due to numa_off, it is worth
> hardening the codes in try_offline_node(), quiting if !pgdat.
>
> Signed-off-by: Jia He <justin.he@arm.com>
> ---
> mm/memory_hotplug.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index da374cd3d45b..e1e290577b45 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1680,6 +1680,9 @@ void try_offline_node(int nid)
> pg_data_t *pgdat = NODE_DATA(nid);
> int rc;
>
> + if (WARN_ON(!pgdat))
> + return;
> +
> /*
> * If the node still spans pages (especially ZONE_DEVICE), don't
> * offline it. A node spans memory after move_pfn_range_to_zone(),
>
Hm. If I am not wrong, somebody used add_memory() with another nid than
try_remove_memory()?
Or did we pass the node_possible(nid) check in add_memory_resource(),
and succeeded to add to nid==-1?
Having that said, this feels somewhat wrong, especially checking against
pgdat down in try_offline_node(). It really has to be the same nid as
used when adding - and that nid has to be sane.
--
Thanks,
David / dhildenb
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next prev parent reply other threads:[~2020-07-06 7:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 1:19 [PATCH 0/3] Fix and enable pmem as RAM on arm64 Jia He
2020-07-06 1:19 ` [PATCH 1/3] arm64/numa: set numa_off to false when numa node is fake Jia He
2020-07-06 8:02 ` David Hildenbrand
2020-07-06 12:36 ` Justin He
2020-07-06 13:56 ` David Hildenbrand
2020-07-06 10:29 ` Jonathan Cameron
2020-07-06 10:46 ` Jonathan Cameron
2020-07-06 12:47 ` Justin He
2020-07-06 13:03 ` Jonathan Cameron
2020-07-06 1:19 ` [PATCH 2/3] mm/memory_hotplug: harden try_offline_node against bogus nid Jia He
2020-07-06 7:57 ` David Hildenbrand [this message]
2020-07-06 13:45 ` Justin He
2020-07-06 1:19 ` [PATCH 3/3] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done Jia He
2020-07-06 7:49 ` David Hildenbrand
2020-07-07 22:10 ` Dan Williams
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