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Commit be39f196 authored by Dominik Dingel's avatar Dominik Dingel Committed by Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 1db9e051

arch/s390/mm/pgtable.c

+13 −8
Original line number Diff line number Diff line
@@ -1087,10 +1087,9 @@ static unsigned long page_table_realloc_pmd(struct mmu_gather *tlb, 
			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 */
@@ -1128,12 +1127,14 @@ 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,

static unsigned long page_table_realloc(struct mmu_gather *tlb, struct mm_struct *mm,

					unsigned long addr, unsigned long end)

{

	unsigned long next;
@@ -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;