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s390/mm,ptdump: hold memory hotplug lock while walking for kernel page table dump

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This is the s390 variant of commit bf2b59f60e ("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>
This commit is contained in:
Heiko Carstens 2020-09-07 17:11:36 +02:00 committed by Vasily Gorbik
parent 9d719d39aa
commit 36c2733c43
1 changed files with 2 additions and 0 deletions
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2
arch/s390/mm/dump_pagetables.c
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@ -129,7 +129,9 @@ static int ptdump_show(struct seq_file *m, void *v)
.marker = address_markers, .marker = address_markers,
}; };
get_online_mems();
ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
put_online_mems();
return 0; return 0;
} }
DEFINE_SHOW_ATTRIBUTE(ptdump); DEFINE_SHOW_ATTRIBUTE(ptdump);