s390/mm: page_table_realloc returns failure
There is a possible race between setting has_pgste and reallocation of the
page_table, change the order to fix this.
Also page_table_alloc_pgste can fail, in that case we need to backpropagte this
as -ENOMEM to the caller of page_table_realloc.
Based on a patch by Christian Borntraeger <borntraeger@de.ibm.com>.
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 94f37a9..a9be088 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -1087,10 +1087,9 @@
continue;
/* Allocate new page table with pgstes */
new = page_table_alloc_pgste(mm, addr);
- if (!new) {
- mm->context.has_pgste = 0;
- continue;
- }
+ if (!new)
+ return -ENOMEM;
+
spin_lock(&mm->page_table_lock);
if (likely((unsigned long *) pmd_deref(*pmd) == table)) {
/* Nuke pmd entry pointing to the "short" page table */
@@ -1128,13 +1127,15 @@
if (pud_none_or_clear_bad(pud))
continue;
next = page_table_realloc_pmd(tlb, mm, pud, addr, next);
+ if (unlikely(IS_ERR_VALUE(next)))
+ return next;
} while (pud++, addr = next, addr != end);
return addr;
}
-static void page_table_realloc(struct mmu_gather *tlb, struct mm_struct *mm,
- unsigned long addr, unsigned long end)
+static unsigned long page_table_realloc(struct mmu_gather *tlb, struct mm_struct *mm,
+ unsigned long addr, unsigned long end)
{
unsigned long next;
pgd_t *pgd;
@@ -1145,7 +1146,11 @@
if (pgd_none_or_clear_bad(pgd))
continue;
next = page_table_realloc_pud(tlb, mm, pgd, addr, next);
+ if (unlikely(IS_ERR_VALUE(next)))
+ return next;
} while (pgd++, addr = next, addr != end);
+
+ return 0;
}
/*
@@ -1165,9 +1170,9 @@
/* split thp mappings and disable thp for future mappings */
thp_split_mm(mm);
/* Reallocate the page tables with pgstes */
- mm->context.has_pgste = 1;
tlb_gather_mmu(&tlb, mm, 0, TASK_SIZE);
- page_table_realloc(&tlb, mm, 0, TASK_SIZE);
+ if (!page_table_realloc(&tlb, mm, 0, TASK_SIZE))
+ mm->context.has_pgste = 1;
tlb_finish_mmu(&tlb, 0, TASK_SIZE);
up_write(&mm->mmap_sem);
return mm->context.has_pgste ? 0 : -ENOMEM;