From 36c2733c439caa424fe2b7dded870913dcb868ac Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@linux.ibm.com>
Date: Mon, 7 Sep 2020 17:11:36 +0200
Subject: [PATCH] s390/mm,ptdump: hold memory hotplug lock while walking for
kernel page table dump
This is the s390 variant of commit bf2b59f60ee1 ("arm64/mm: Hold
memory hotplug lock while walking for kernel page table dump").
Right now this doesn't fix any real bug, however as soon as kvm
patches get merged which make use of memory remove we might end up
dereferencing/accessing freed page tables.
Therefore fix this potential bug already now.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
---
arch/s390/mm/dump_pagetables.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c
index 93a29e2f13d42..3c5e4055a3d23 100644
--- a/arch/s390/mm/dump_pagetables.c
+++ b/arch/s390/mm/dump_pagetables.c
@@ -129,7 +129,9 @@ static int ptdump_show(struct seq_file *m, void *v)
.marker = address_markers,
};
+ get_online_mems();
ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
+ put_online_mems();
return 0;
}
DEFINE_SHOW_ATTRIBUTE(ptdump);
--
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