[S390] pgtables: Fix race in enable_sie vs. page table ops
The current enable_sie code sets the mm->context.pgstes bit to tell
dup_mm that the new mm should have extended page tables. This bit is also
used by the s390 specific page table primitives to decide about the page
table layout - which means context.pgstes has two meanings. This can cause
any kind of bugs. For example - e.g. shrink_zone can call
ptep_clear_flush_young while enable_sie is running. ptep_clear_flush_young
will test for context.pgstes. Since enable_sie changed that value of the old
struct mm without changing the page table layout ptep_clear_flush_young will
do the wrong thing.
The solution is to split pgstes into two bits
- one for the allocation
- one for the current state
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 1a928f8..7fc7613 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -679,7 +679,7 @@
static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
- if (mm->context.pgstes)
+ if (mm->context.has_pgste)
ptep_rcp_copy(ptep);
pte_val(*ptep) = _PAGE_TYPE_EMPTY;
if (mm->context.noexec)
@@ -763,7 +763,7 @@
struct page *page;
unsigned int skey;
- if (!mm->context.pgstes)
+ if (!mm->context.has_pgste)
return -EINVAL;
rcp_lock(ptep);
pgste = (unsigned long *) (ptep + PTRS_PER_PTE);
@@ -794,7 +794,7 @@
int young;
unsigned long *pgste;
- if (!vma->vm_mm->context.pgstes)
+ if (!vma->vm_mm->context.has_pgste)
return 0;
physpage = pte_val(*ptep) & PAGE_MASK;
pgste = (unsigned long *) (ptep + PTRS_PER_PTE);
@@ -844,7 +844,7 @@
static inline void ptep_invalidate(struct mm_struct *mm,
unsigned long address, pte_t *ptep)
{
- if (mm->context.pgstes) {
+ if (mm->context.has_pgste) {
rcp_lock(ptep);
__ptep_ipte(address, ptep);
ptep_rcp_copy(ptep);