sparc64: Do not insert non-valid PTEs into the TSB hash table.
The assumption was that update_mmu_cache() (and the equivalent for PMDs) would only be called when the PTE being installed will be accessible by the user. This is not true for code paths originating from remove_migration_pte(). There are dire consequences for placing a non-valid PTE into the TSB. The TLB miss frramework assumes thatwhen a TSB entry matches we can just load it into the TLB and return from the TLB miss trap. So if a non-valid PTE is in there, we will deadlock taking the TLB miss over and over, never satisfying the miss. Just exit early from update_mmu_cache() and friends in this situation. Based upon a report and patch from Christopher Alexander Tobias Schulze. Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -351,6 +351,10 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *
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mm = vma->vm_mm;
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/* Don't insert a non-valid PTE into the TSB, we'll deadlock. */
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if (!pte_accessible(mm, pte))
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return;
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spin_lock_irqsave(&mm->context.lock, flags);
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#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
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@ -2619,6 +2623,10 @@ void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
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pte = pmd_val(entry);
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/* Don't insert a non-valid PMD into the TSB, we'll deadlock. */
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if (!(pte & _PAGE_VALID))
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return;
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/* We are fabricating 8MB pages using 4MB real hw pages. */
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pte |= (addr & (1UL << REAL_HPAGE_SHIFT));
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