From c4f0e5cfde354b1d6cf2388c0920264985c6c139 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@linux.ibm.com>
Date: Tue, 24 Aug 2021 15:21:44 +0200
Subject: [PATCH] s390/mm,pageattr: fix walk_pte_level() early exit
In case of splitting to 4k mapping the early exit in walk_pte_level()
must only be taken iff flags is equal to SET_MEMORY_4K.
Currently the early exit is taken if the flag is set, and also others
might be set. This may lead to the situation that a mapping is split
but other changes are not done, like e.g. setting pages to R/W.
There is currently no such caller, but there might be in the future.
Fixes: b3e1a00c8fa4 ("s390/mm: implement set_memory_4k()")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
arch/s390/mm/pageattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
index 45197b71d55fd..fdc86c0e4e6ca 100644
--- a/arch/s390/mm/pageattr.c
+++ b/arch/s390/mm/pageattr.c
@@ -86,7 +86,7 @@ static int walk_pte_level(pmd_t *pmdp, unsigned long addr, unsigned long end,
{
pte_t *ptep, new;
- if ((flags & SET_MEMORY_4K) == SET_MEMORY_4K)
+ if (flags == SET_MEMORY_4K)
return 0;
ptep = pte_offset_kernel(pmdp, addr);
do {
--
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