From: Miaohe Lin <linmiaohe@huawei.com> mainline inclusion from mainline-v6.3-rc1 commit 3109de308987ceae413ee015038d51e2a86c7806 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6POXN CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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. Link: https://lkml.kernel.org/r/20220418141253.24298-10-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Charan Teja Kalla <charante@codeaurora.org> Cc: David Hildenbrand <david@redhat.com> Cc: Pintu Kumar <pintu@codeaurora.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ze Zuo <zuoze1@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> --- mm/compaction.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 509dee7c2f38..8e8017d909b7 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2949,7 +2949,8 @@ 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; } -- 2.25.1