From: Gerald Schaefer gerald.schaefer@de.ibm.com
commit 582b4e55403e053d8a48ff687a05174da9cc3fb0 upstream.
On s390 there currently is no implementation of pud_write(). That was ok as long as we had our own implementation of get_user_pages_fast() which checked for pud protection by testing the bit directly w/o using pud_write(). The other callers of pud_write() are not reachable on s390.
After commit 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") we use the generic get_user_pages_fast(), which does call pud_write() in pud_access_permitted() for FOLL_WRITE access on a large pud. Without an s390 specific pud_write(), the generic version is called, which contains a BUG() statement to remind us that we don't have a proper implementation. This results in a kernel panic.
Fix this by providing an implementation of pud_write().
Cc: stable@vger.kernel.org # 5.2+ Fixes: 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") Signed-off-by: Gerald Schaefer gerald.schaefer@de.ibm.com Reviewed-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/include/asm/pgtable.h | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -750,6 +750,12 @@ static inline int pmd_write(pmd_t pmd) return (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE) != 0; }
+#define pud_write pud_write +static inline int pud_write(pud_t pud) +{ + return (pud_val(pud) & _REGION3_ENTRY_WRITE) != 0; +} + static inline int pmd_dirty(pmd_t pmd) { return (pmd_val(pmd) & _SEGMENT_ENTRY_DIRTY) != 0;