KVM: s390/mm: Fix page table locking vs. split pmd lock
commit ec66ad66a0
(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: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -1279,6 +1279,7 @@ static unsigned long page_table_realloc_pmd(struct mmu_gather *tlb,
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{
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unsigned long next, *table, *new;
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struct page *page;
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spinlock_t *ptl;
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pmd_t *pmd;
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pmd = pmd_offset(pud, addr);
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@ -1296,7 +1297,7 @@ again:
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if (!new)
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return -ENOMEM;
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spin_lock(&mm->page_table_lock);
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ptl = pmd_lock(mm, pmd);
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if (likely((unsigned long *) pmd_deref(*pmd) == table)) {
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/* Nuke pmd entry pointing to the "short" page table */
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pmdp_flush_lazy(mm, addr, pmd);
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@ -1310,7 +1311,7 @@ again:
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page_table_free_rcu(tlb, table);
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new = NULL;
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}
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spin_unlock(&mm->page_table_lock);
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spin_unlock(ptl);
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if (new) {
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page_table_free_pgste(new);
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goto again;
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