redonkable/alistair23-linux
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s390/mm: page_table_realloc returns failure

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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>
This commit is contained in:
Dominik Dingel 2013-10-31 10:01:16 +01:00 committed by Martin Schwidefsky
parent 1db9e0513d
commit be39f1968e
1 changed files with 13 additions and 8 deletions
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21
arch/s390/mm/pgtable.c
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@ -1087,10 +1087,9 @@ again:
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 @@ static unsigned long page_table_realloc_pud(struct mmu_gather *tlb,
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 @@ static void page_table_realloc(struct mmu_gather *tlb, struct mm_struct *mm,
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 @@ int s390_enable_sie(void)
/* 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;