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>

diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
index 45197b7..fdc86c0 100644 (file)
--- 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 {