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Commit 55e4283c authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Martin Schwidefsky
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KVM: s390/mm: Fix page table locking vs. split pmd lock 



commit ec66ad66 (s390/mm: enable
split page table lock for PMD level) activated the split pmd lock
for s390. Turns out that we missed one place: We also have to take
the pmd lock instead of the page table lock when we reallocate the
page tables (==> changing entries in the PMD) during sie enablement.

Cc: stable@vger.kernel.org # 3.15+
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent a94fa154

arch/s390/mm/pgtable.c

+3 −2
Original line number Diff line number Diff line
@@ -1279,6 +1279,7 @@ static unsigned long page_table_realloc_pmd(struct mmu_gather *tlb, 
{

	unsigned long next, *table, *new;

	struct page *page;

	spinlock_t *ptl;

	pmd_t *pmd;



	pmd = pmd_offset(pud, addr);
@@ -1296,7 +1297,7 @@ static unsigned long page_table_realloc_pmd(struct mmu_gather *tlb, 
		if (!new)

			return -ENOMEM;



		spin_lock(&mm->page_table_lock);

		ptl = pmd_lock(mm, pmd);

		if (likely((unsigned long *) pmd_deref(*pmd) == table)) {

			/* Nuke pmd entry pointing to the "short" page table */

			pmdp_flush_lazy(mm, addr, pmd);
@@ -1310,7 +1311,7 @@ static unsigned long page_table_realloc_pmd(struct mmu_gather *tlb, 
			page_table_free_rcu(tlb, table);

			new = NULL;

		}

		spin_unlock(&mm->page_table_lock);

		spin_unlock(ptl);

		if (new) {

			page_table_free_pgste(new);

			goto again;