powerpc/mm: Make sure a local_irq_disable prevent a parallel THP split
We have generic code like the one in get_futex_key that assume that a local_irq_disable prevents a parallel THP split. Support that by adding a dummy smp call function after setting _PAGE_SPLITTING. Code paths like get_user_pages_fast still need to check for _PAGE_SPLITTING after disabling IRQ which indicate that a parallel THP splitting is ongoing. Now if they don't find _PAGE_SPLITTING set, then we can be sure that parallel split will now block in pmdp_splitting flush until we enables IRQ Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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@ -647,6 +647,11 @@ void pmdp_splitting_flush(struct vm_area_struct *vma,
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if (old & _PAGE_HASHPTE)
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hpte_do_hugepage_flush(vma->vm_mm, address, pmdp);
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}
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/*
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* This ensures that generic code that rely on IRQ disabling
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* to prevent a parallel THP split work as expected.
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*/
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kick_all_cpus_sync();
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}
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/*
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