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From: Miaohe Lin <linmiaohe@huawei.com>
To: <akpm@linux-foundation.org>
Cc: <vbabka@suse.cz>, <pintu@codeaurora.org>,
	<charante@codeaurora.org>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>, <linmiaohe@huawei.com>
Subject: [PATCH 09/12] mm: compaction: avoid possible NULL pointer dereference in kcompactd_cpu_online
Date: Mon, 18 Apr 2022 22:12:50 +0800	[thread overview]
Message-ID: <20220418141253.24298-10-linmiaohe@huawei.com> (raw)
In-Reply-To: <20220418141253.24298-1-linmiaohe@huawei.com>

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.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/compaction.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 562f274b2c51..82c54d70a978 100644
--- 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;
 }
-- 
2.23.0


  parent reply	other threads:[~2022-04-18 15:13 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 ` Miaohe Lin [this message]
2022-04-19  3:55   ` [PATCH 09/12] mm: compaction: avoid possible NULL pointer dereference in kcompactd_cpu_online Andrew Morton
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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