From: Andrew Morton <akpm@linux-foundation.org>
To: Miaohe Lin <linmiaohe@huawei.com>
Cc: <vbabka@suse.cz>, <pintu@codeaurora.org>,
<charante@codeaurora.org>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>,
David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH 09/12] mm: compaction: avoid possible NULL pointer dereference in kcompactd_cpu_online
Date: Mon, 18 Apr 2022 20:55:31 -0700 [thread overview]
Message-ID: <20220418205531.2e4ed0f72e0e537ef55c6468@linux-foundation.org> (raw)
In-Reply-To: <20220418141253.24298-10-linmiaohe@huawei.com>
Please cc David H on memhotplug stuff.
On Mon, 18 Apr 2022 22:12:50 +0800 Miaohe Lin <linmiaohe@huawei.com> wrote:
> It's possible that kcompactd_run could fail to run kcompactd for a hot
> added node and leave pgdat->kcompactd as NULL. So pgdat->kcompactd should
> be checked here to avoid possible NULL pointer dereference.
>
> ..
>
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -3052,7 +3052,8 @@ static int kcompactd_cpu_online(unsigned int cpu)
>
> if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
> /* One of our CPUs online: restore mask */
> - set_cpus_allowed_ptr(pgdat->kcompactd, mask);
> + if (pgdat->kcompactd)
> + set_cpus_allowed_ptr(pgdat->kcompactd, mask);
> }
> return 0;
> }
Why not fail to bring the node online if kcompactd_run() failed?
Also, should we panic the system if kcompactd_run() failed in
kcompactd_init()?
next prev parent reply other threads:[~2022-04-19 3:55 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-18 14:12 [PATCH 00/12] A few cleanup and fixup patches for compaction Miaohe Lin
2022-04-18 14:12 ` [PATCH 01/12] mm: compaction: remove unneeded return value of kcompactd_run Miaohe Lin
2022-04-18 14:12 ` [PATCH 02/12] mm: compaction: remove unneeded pfn update Miaohe Lin
2022-04-18 14:12 ` [PATCH 03/12] mm: compaction: remove unneeded assignment to isolate_start_pfn Miaohe Lin
2022-04-18 14:12 ` [PATCH 04/12] mm: compaction: clean up comment for sched contention Miaohe Lin
2022-04-18 14:12 ` [PATCH 05/12] mm: compaction: clean up comment about suitable migration target recheck Miaohe Lin
2022-04-18 14:12 ` [PATCH 06/12] mm: compaction: use COMPACT_CLUSTER_MAX in compaction.c Miaohe Lin
2022-04-18 14:12 ` [PATCH 07/12] mm: compaction: use helper compound_nr in isolate_migratepages_block Miaohe Lin
2022-04-18 14:12 ` [PATCH 08/12] mm: compaction: clean up comment about async compaction in isolate_migratepages Miaohe Lin
2022-04-18 14:12 ` [PATCH 09/12] mm: compaction: avoid possible NULL pointer dereference in kcompactd_cpu_online Miaohe Lin
2022-04-19 3:55 ` Andrew Morton [this message]
2022-04-19 6:47 ` Miaohe Lin
2022-04-19 7:42 ` David Hildenbrand
2022-04-19 11:05 ` Miaohe Lin
2022-04-18 14:12 ` [PATCH 10/12] mm: compaction: make compaction_zonelist_suitable return false when COMPACT_SUCCESS Miaohe Lin
2022-04-18 14:12 ` [PATCH 11/12] mm: compaction: simplify the code in __compact_finished Miaohe Lin
2022-04-18 14:12 ` [PATCH 12/12] mm: compaction: make sure highest is above the min_pfn Miaohe Lin
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