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[S390] pgtables: Fix race in enable_sie vs. page table ops

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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>
This commit is contained in:
Christian Borntraeger
2008-10-28 11:10:15 +01:00
committed by Martin Schwidefsky
parent 2c78091405
commit 250cf776f7
4 changed files with 30 additions and 16 deletions
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8
arch/s390/include/asm/pgtable.h
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@@ -679,7 +679,7 @@ static inline void pmd_clear(pmd_t *pmd)
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 @@ static inline int kvm_s390_test_and_clear_page_dirty(struct mm_struct *mm,
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 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
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_ipte(unsigned long address, pte_t *ptep)
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);